Manual

PROJECT ON CAPACITY ENHANCEMENT FOR ESTABLISHING MEXICAN NORMS
OF WATER QUALITY CRITERIA
SEPARATE VOLUME OF THE FINAL REPORT
Manual
for Establishment of Environmental Water
Quality Criteria
Version 1.1
[July 2010]
This manual describes necessary consideration, information and procedure for establishing
environmental water quality criteria based on the activities on the JICA project and guidelines
published by major environmentally-advanced countries/organizations.
Table of Contents
Abbreviations
Introduction
1
1.
Structure of the manual
2
2.
Definition of criteria
2
3.
Relationship between Criteria and Standard
5
4.
Procedure for establishment of criteria
8
4.1 General procedure
8
4.2 Selection of criteria parameters
11
4.3 Determination of concentration
13
5.
Categorization of criteria
14
6.
Necessary information/consideration to establish criteria
15
7.
6.1 Public use / Supply source for drinking water
15
6.2 Irrigation use
16
6.3 Livestock
18
6.4 Recreational use
18
6.5 Amenity use
18
6.6 Protection of aquatic life, wild life, human health
18
6.7 Commercial and sports fishing / aquaculture
19
6.8 Suspended particulate matter and sediment
19
6.9 Industrial water
19
6.10 Others
20
Consideration from various viewpoints to establish criteria
21
7.1 Industrial effluent
21
7.2 Toxic substances
25
7.3 Risk assessment
27
7.4 Conservation of aquatic life
41
7.5 Accuracy of chemical analysis
49
7.6 Monitoring situation
52
References
Appendix
Abbreviations
AWQC
: Ambient Water Quality Criteria
BCF
: Bio-concentration Factor
EC50
: 50% Effective Concentration
EQL
: Experimental Quantification Limit
EU
: European Union
EHE
: Estimated Human Exposure
USEPA
: Environmental Protection Agency, USA
FAO
: Food and Agricultural Organization
IARC
: International Agency for Research on Cancer
IQL
: Instrumental Quantification Limit
JICA
: Japan International Cooperation Agency
LC50
: 50% Lethal Concentration
LOAEL
: Lowest Observed Adverse Effect Level
LOEC
: Lowest Observed Effect Concentration
LOG POW
: Octanol-Water Partition Coefficient
MPC
: Maximum Permissible Concentration
NOAEL
: No Observed Adverse Effect Level
NOEC
: No observed Effect Concentration
PFC
: Parameters for Criteria
POPs
: Persistence Organic Pollutants
QL
: Quantification Limit
RETC
: Registro de Emisiones y Transferencia de Contaminantes
TDI
: Tolerable Daily Intake
TDS
: Total Dissolved Solid
UNEP
: United Nations Environmental Program
WHO
: World Health Organization
WQC
: Water Quality Criteria
Introduction
As a tool for pollution control, environmental/ambient water quality standards and objectives
are used to identify the present situation in an area. They have judicial power to control the
environment in a target area.
And the environmental/ambient water quality criteria
(hereinafter referred to as WQC) are used to set-up environmental/ambient water quality
standards and objectives.
In the JICA project, “The Project on Capacity Enhancement for Establishing Mexican Norm of
Water Quality Criteria (2008-2010)” (hereinafter referred as the Project), proposal for new
environmental water quality criteria were released.
This manual describes the general procedures to establish environmental water quality criteria
based on the activities which were carried out regarding the Project and guidelines by major
environmentally-advanced countries/organizations.
We hope this manual will help people from other countries to develop the basis for establishing
criteria for their own countries.
1
1. Structure of the manual
This manual is divided into two parts.
Part 1 - Basic information regarding water criteria such as its definition and history.
Section 2 – Definition of criteria
Section 3 – Relationship between Criteria and Standard
Part 2 - Technical considerations for establishing environmental water quality criteria.
Section 4 – Procedure for establishment of criteria
Section 5 – Categorization of criteria
Section 6 – Necessary information/consideration to establish criteria
Section 7 – Consideration from various viewpoints to establish criteria
The descriptions in the manual are general as much as possible, considering that this manual
will be applied in many countries, not just Mexico.
Special topics confined to the Project or examples to be referred such as calculations using
specified equations are introduced in dialogue boxes.
2. Definition of criteria
Helmar et al (WHO, 1997) defines water quality criteria (hereinafter referred to as criteria) as
shown in Table 1. That is: Numerical concentration or narrative statement recommended to
support and maintain a designated water use.
USEPA defines narrative criteria rather than numerical criteria, which is applied when
numerical criteria is not available.
Narrative criteria also can be used
where toxicity cannot be traced to a
particular pollutant.
Topic 1: Definition in the
Project
In this manual, only numerical criteria is
handled as environmental water quality
Criteria (Environmental Water
criteria.
Quality Criteria), in the Project, are
It is considered that the criteria will be
used as references to set up water
quality objective or water quality
considered as references to be used
for establishment of
objective/standard in a certain area.
2
standard.
It includes the name of parameter as well as actual concentration/value.
Criteria generally cover the entire target country/area, although water quality objective/standard
aim at a specific, river basin. This means that the parameters and their concentrations are
described generally.
When they are used in a specific site/river basin, they must be modified
based on the situation of the target area.
Table 1 Definitions related to water quality and pollution control
Source: Helmar et al, WHO, 1997
Criteria are used as one of the management tools for water environment.
USEPA (1993)
shows the approach to pollution control using water quality standard. (See Figure 1)
Canada (Figure 2, CCME, 1999) also introduced the role of water quality guidelines and
objectives in water quality management. The objectives in this case are treated as criteria.
This means criteria are fundamental for water management.
3
Determine Protection Level
Measure Progress
Conduct Water Quality Assessment
Monitor and Enforce Compliance
Establish Priorities
Evaluate Water Quality Standard
Establish Source Control
for Targeted Waters
Define and Allocate Control
Responsibilities
Source: USEPA (1993)
Figure 1
Water Quality-Based Approach to Pollution Control
4
Source: CCME, 1999
Figure 2
Role of Water Quality Guidelines and Objectives in Water Quality
Management
3. Relationship between Criteria and Standard
This section introduces relationship between water quality criteria and standard in several
countries; it is summarized in Table 2.
5
Table 2
Relationship between Criteria and Standard in several countries
Responsibility
Characteristics Relationship
Relative law
between
Criteria
Standard
Effluent
Control
U.S.A
Federal
government
State
government
USEPA approves
the standard by state
government
England
Federal
government
State
government
Specified
parameters by EU
are obligation
Germany
Federal
government
State
government
Specified
parameters by EU
are obligation
France
State
government
Federal
government
Specified
parameters by EU
are obligation
E.U.
-
-
Uniformed standard
Japan
-
Central
government
State government
can issue additional
standards based on
the local situation
Sources:
U.S.A, http://www.epa.gov/
England, http://www.environment-agency.gov.uk/research/default.aspx
Germany, http://www.bmu.de/english/water_management/
France, http://www.oieau.fr/spip.php?sommaire&lang=en
EU, http://ec.europa.eu/environment/water/index_en.htm
Japan, http://www.env.go.jp/en/
6
Closed
relationship
between water
quality standard
and point source
control is
maintained.
The River Quality
Objectives is used
to decide
discharge
permission.
The Waste Water
Ordinance is
based on the Best
Available
Technology.
Comprehensive
water
management on
water region basis
is carried out.
Combined
approach between
environmental
quality and
emission limit.
Total pollutant
load control is
carried out.
Water Quality Act, 1987
Sustainable Development
Strategy, 1999
Federal Water Act, 2002
French Law n°92-3 Of
January 3, 1992
Water Policy Directive
(2000/60/EC): basic
standard for EU countries
Water Pollution Control
Law, 1995
Topic 2: History of Environmental Water Quality Standards in
Japan
2006
Sixth
2005
2000
1995
1990
1996
1990
1989
1985
1980
1978
1975
1970
1972
1970
Measures against
groundwater
pollution an d oil
spills cau sed by
accidents
institutionalized
Measures against
domestic effluents
institutionalized
1998
1993
Preven tive
measu res against
groundwater
pollution
institutionalized
Improvement of
water qu ality
standards
related to
human health
Addition of new
substances to
water qu ality
stan dards
related to
human health
protection
Water Pollution
Control Law enacted
1965
2003 Basic Law on
Restoration of th e
Ariake and Yatsushiro
Seas enacted
2001 Ministry
of the
Environment
established
1996
Fourth
1991
T hird
1987
Second
1979
Areawide water
pollutant load control
implemented in Tokyo
Bay, Ise Bay an d the
Seto Inland Sea
Areawide total
water pollutant
load control
institu tionalized
Absolu te liability
in trodu ced
2001
Fifth
2005 Amendment of Law
Con cern ing Special Measure
for th e Preservation of Lake
Water Quality enacted
1985 Nitrogen and
phosphorus con trol
stan dards for lakes
and reservoirs
1984 Law Concerning
Special Measure for the
Preservation of Lake
Water Quality enacted
1978 Law Concerning Special
Measures for Conservation of
th e Environment of the Seto
Inland Sea enacted
1973 The interim
Law for
Conservation of th e
Environment of the
Seto Inland Sea
enacted
1970
Environmental
quality standards
for water pollution
established
1993 Basic
Environment
Law en acted
1972 Large-scale
damage to fisheries due
to Red-tide
1971 Environment
Agency established
Relationship between Environmental Water Quality Standard
and Effluent Standard
Effluent Standard (ES)
Effluent Flow
house
hold
National uniform EF
Specified Facilities
by Ministry of the Environment
+
Stringent EF
by local governors
Public Water Area
Sewerage
Plant
Effluent
Standard
(River, Lake, Coast)
Environmental Quality
Standard (EQSs) for
W ater Pollution
By Basic Environment Law
By Sewerage
Law &
W.P.C.L
Source: Kohata, 2008
7
As shown in the Table 2, criteria cover a broader area than standards do in the most countries.
In this sense, this manual discusses the procedures and necessary considerations for establishing
criteria.
4. Procedure for establishment of criteria
This section introduces the procedure for establishment of criteria briefly.
Although many
approaches for establishment of criteria are considered, two major ones (selection of criteria
parameters and determination of parameter’s concentrations) are discussed in this manual.
4.1 General procedure
USEPA (2000) introduces the process for criteria development for nutrient as discussed below
and as shown in Figure 3.
1. Identify water quality needs and goals with regard to managing nutrient enrichment
problems
2. Classify rivers and streams first by type, and then by trophic status
3. Select variables for monitoring nutrients
4. Design a sampling program for monitoring nutrients and algal biomass in rivers and
streams
5. Collect data and build database
6. Analyze data
7. Develop criteria based on reference conditions and data analyses
8. Implement nutrient control strategies
9. Monitor effectiveness of nutrient control strategies and reassess the validity of nutrient
criteria
8
Selection of
Parameters
Determination of
Concentrations
Source: USEPA, 2000
Figure 3
Criteria Development Flow
The procedure introduced by USEPA focuses on the criteria for nutrient, but it is considered
that all necessary procedures for development criteria are covered.
Although many approaches for establishment of criteria are considered, there are two major
parts: the selection of criteria parameters and the determination of parameter’s concentrations as
yellow-colored shown in Figure 3 (the words ‘variables’ and ‘ranges’ are used instead in the
figure) are discussed in this manual.
9
Topic 3: Establishment flow in the Project
The Project followed the procedure described in the flow chart shown below.
Output 1, 2 and 3 in the figure are the expected results from the Project.
- Output 1 (Capacity to identify parameters for WQC in freshwater) is necessary ability for
CONAGUA to establish WQC based on present conditions, which would be an
indicator for water management and for countermeasures to pollution.
- Output 2 (Capacity to decide maximum permissible concentrations) is ability to decide
practical value for each criteria parameter based on various conditions such as toxicity
of parameter, aquatic biota in the target area, number of population, land use,
industrial effluents and their future transition.
- Output 3 (Analysis with sufficient reliability) is to secure accuracy, which is scientifically
appropriate and practical for supporting the Output 1 and the Output 2.
Output 1
Former Criteria
RETC
Present state of
pesticide use
National
studies
Information
by substance
Analysis by
parameter
Analytical technique
Quality control
Information
from pilot areas
Pre-selection
Risk evaluation
Technical transfer of
analytical methods
Determination
detection limits
Output 3
of
Hierarchization
Decision of draft criteria
Strategy by
water use
Confirmation on consistency
in analytical precision
No
Feasibility?
Output 2
Change of priority
SOPs
Yes
New criteria values
Manual for the
formulation of
criteria
10
Proposal for
new criteria
4.2 Selection of criteria parameters
Parameters are measurable attributes that can be used to evaluate or predict the condition of
environmental situation. (USEPA, 2000) Those parameters (hereinafter referred to as PFC:
Parameters For Criteria), therefore, must represent the situation of the target area, mainly the
entire country.
In that sense, a lot of data is necessary to use to select PFC.
Examples and guidelines from other country and international organizations can also be referred
to.
It is necessary to select PFC which is related to health, such as conservation of the water source,
from viewpoint of risk assessment.
For utilization of water in the industry, agriculture, fish, etc, it is necessary to consider not only
water resources and its environment, but also type of industry, distribution, its further
development, etc.
11
Topic 4: Consideration for selection of parameters in the Project
After collecting data, following procedure to clarify the roles of WQC was used considering
situation in the Project.
a. Evaluation of method to select PFC in the Draft Criteria (revised criteria in 2005 based
on the previous criteria established in 1989)
- Appropriateness of determination of PFC (conservation of human health,
conservation of aquatic life, water usage)
- Necessary information related to target chemicals is enough?
- Differences to approach to risk assessment between countries are considered?
b. Collecting information about water basins in Mexico (including information of the pilot
area)
- Differences between discharge source, discharge volume and water area
- Monitoring of ambient concentration and its annual change
- Estimation of exposure amount in water area
c. Collecting information relating to evaluation of exposure
- Application of target chemical substances
- Process of exposure and its medium (drinking water, foods, primary contact,
absorption)
- Concentration of exposure and its degree
d. Selection of PFC and MPC based on the risk assessment
- Relationship between NOAEL (No Observed Adverse Effect Level: (end point) and
TDI (Tolerable Daily Intake) for the target parameters used in Mexico
- Decision method for the Maximum Permissible Concentration of selected PFC by
risk assessment
e. Selection of PFC and MPC based on the viewpoint of conservation of aquatic life
- Selection and prioritization of PFC using ambient data in Mexico
- Determination of MPC using toxicity database
f. Evaluation of MPC based on the viewpoint of analytical qualification limit
- Relationship between IQL (Instrumental Quantification Limit) and EQL
(Experimental Quantification Limit)
12
4.3 Determination of concentration
Concentration of PFC is often treated as Maximum Permissible Concentration (hereinafter
referred to as MPC), which is the highest concentration allowed to be in the environment.
Three types of approach for determination of MPC are considered, analytical viewpoint,
toxicological viewpoint and viewpoint from risk assessment.
The relationship between those three approaches is considered as shown in Figure 4.
Under the viewpoints of Risk Assessment and Toxicology, existing data or database are used to
determine MPC and experimental test is occasionally carried out, while under the analytical
viewpoint derives MPC based on the analytical condition such as quantification limit.
Data
Experi
mental
Test
Database
Toxicology
Risk
Assessment
MPC
Chemical
Analysis
Figure 4 Relationship Between Approaches for Determination of MPC
Details of those three approaches are discussed in Section 0.
Determination of MPC referring to technical levels of public water-treatment-facility or
industrial-treatment-facility, the extent of its spread, tendency of effluent standard and
reinforcement of regulation is also important.
In the following sections, considerations for selection of PFC from various viewpoints are
described.
13
5. Categorization of criteria
Table 3 summarizes water use for criteria/standard in several countries. All countries in Table 3
prioritize the criteria into several water uses: drinking water, agriculture and conservation of
aquatic life/human health.
Table 3
Water Use on Water Quality Criteria/Standard in Other Countries
No.
of
Use
Water Use (refer to the notes numbered 1-10 below)
1
2
3
4
5
6
7
8


The Project
3


()
Mexico (1989)
5




WHO
8




CANADA
5

EU
4

EPA
6


4



Germany
5




Japan
8




Australia &
New Zealand
9
10




















Notes - Water Uses:
1.
Supply source for drinking-water
2.
Irrigation
3.
Livestock
4.
Recreational use
5.
Amenity use
6.
Protection of aquatic life, wild life, human health
7.
Commercial and sports fishing / aquaculture
8.
Suspended particulate matter and sediment (sediments for improvement of soils)
9.
Industrial water
10. Other
14

Topic 5: Category in the Project
Based on the reality of water environmental situation, inspection system, etc. in
Mexico, categorization of criteria was decided as shown in the following figure.
Characteristically, the category ‘Human health’ covers all categories.
WQC
Human Health
Agriculture
Irrigation,
Livestock &
Aquaculture
Water Supply
Conservation
Source
of Aquatic
Life
6. Necessary information/consideration to establish criteria
This section describes the necessary information and the considerations taken into account to
establish WQC for each water use.
6.1 Public use / Supply source for drinking water
This category is basically criteria for water quality in a water body (lake, reservoir, river, etc).
This category is applied to raw water or water which is treated prior to purification for
distribution in the potable water network. Basically, it is the water quality criteria for water
supply.
Parameters include microbiological characteristics (e.g. microorganism, pathogenic organism),
toxic compounds, parameters affecting the taste and odor of the water (e.g. phenols), parameters
with an indirect effect on water quality (e.g. color, ammonium), organic substances and
inorganic substances.
15
6.2 Irrigation use
Water quality for irrigation is very important, because if it does not have the appropriate criteria,
negative effects could be seen in the crops, soil, human health and even in the water source.
Possibility of contaminating the environment exists when the water used for irrigation contains
pollutant substances, which may reach the groundwater by infiltration, accumulating in the
crops and eventually reach to human beings through the food chain.
The water in its natural form contains ions, dissolved salts and microorganisms, and if those are
in high concentrations they can cause, amongst other things, negative effects such as:
-
Sodium affects soil structure and reduces the rate of water movement in soil. Sodium
specifically causes damage in fruits.
-
Phytotoxic trace elements such as Boron, heavy metals and pesticides may stunt the growth
of plants.
Detailed information on the negative effects of each one of the WQC can be consulted in
references provided by the USEPA, WHO, South Africa and Australia-New Zealand. (See
Table 4)
Table 4 Key Issues Concerning Agricultural Irrigation Water Quality Effects on
Soil, Crops and Water Resources
Element
Effect
Soil
Salinization of the root growth zone
Soil structural instability.
Build-up of contaminants in soil
Alteration and modification on soil biota
Release of contaminants from soil to crops and pastures
Crops
Yield reduction
Product quality
Salt tolerance
Foliar injury
Uptake of toxicants in produce for human consumption
Contamination by pathogens
Water
Deep drainage and leaching below root zone
resources
Movement of sales, nutrients and contaminants to ground waters and surface
waters
Other
Quantity and seasonality of rainfall
16
important
Soil properties
factors
Crop and pasture species and management options
Land type
Groundwater depth and quality
Source: Australian and New Zealand guidelines, 2000
Basic idea of the criteria for irrigation water use is to maintain the productivity of irrigated
agricultural land and associated water resources, in accordance with the principles for
conservation of human health.
High quality water is recommended to be used for irrigation in the guideline by WHO and
Australia/New Zealand. In some countries, however, untreated industrial wastewater may be
used for irrigation. This means toxic elements such as arsenic, cadmium, chromium, copper,
lead, mercury, zinc, etc., which affect humans, are included.
Also pathogenic organisms
(either micro or macro) are of concern.
In that case, WHO suggests referring to the guidelines for wastewater.
The criteria established by international organizations and countries such as the FAO, USDA,
EPA, Canada, South Africa, European Union and Australia/New Zealand for agricultural
irrigation include the use of supply sources with high water quality. Therefore, such references
should be considered as the basis for the establishment of the WQC for agricultural irrigation. In
other countries, the supply sources for agricultural irrigation show high contamination levels
caused by raw municipal and industrial wastewater discharges. This means that this water will
include high concentrations of organic matter, nutrients, pathogen organisms, as well as toxic
elements such as arsenic, cadmium, chromium, copper, lead, mercury, zinc, etc. which affect
soil, crops, aquatic resources and human beings, and therefore should be considered to be
included in the WQC. In this case, it is recommended to refer to the guidelines established by
the EPA, FAO, WHO, Australia/New Zealand, for the reuse of treated wastewaters.
Wastewater irrigation also causes a negative impact on the growth rate of products. (FAO)
That is:
- Accumulation of substances such as salt, which cause soil structure
- Dissolved solids (TDS) in irrigated water cause decline of plant growth due to
increased osmotic pressure.
- High-concentrated ion in irrigated water interference with metabolic process on plant
growth.
FAO also specifies threshold levels of trace metals for crop production.
17
6.3 Livestock
Good water quality is essential for successful livestock and other breeding animal production.
Poor quality water may reduce animal production and impair fertility.
In extreme case,
animals may die.
Some substances contained in water for livestock watering may occasionally be transmitted to
humans.
The scope of the criteria for livestock drinking water includes biological, chemical and
radiological characteristics that may affect animal health and human health.
6.4 Recreational use
This category is mainly applied for the water use for swimming and other water-sport activities.
The priority of this category is to protect human health by preventing water pollution from fecal
material or from contamination by micro-organisms, because it may cause stomach illness, ear,
eye or skin infections. So that fecal coli forms, pathogens and harmful algal species such as
some blue-green algae are considered for the criteria.
Physical and chemical characteristics such as pH, temperature and toxic chemicals might be
considered.
6.5 Amenity use
Basic idea of this category is protection of aesthetic properties of water that could be used for
water friendly facilities such as fountains, parks, irrigation of urban green areas.
Visual and sensory aspects such as water color, free of floating oil or immiscible liquids,
floating debris, nuisance organisms (excessive growth of aquatic plant, phytoplankton scum,
algal mats, and sewage fungus), excessive turbidity and objectionable odors are the parameters
for this category.
6.6 Protection of aquatic life, wild life, human health
Aquatic life is defined as animals, plants and micro-organisms that live in water. Those are
affected directly by the variation of their environmental water.
18
Protection of wildlife and human health is based on the similar consideration, that is: to protect
the target from direct contact with polluted water or to avoid drinking polluted water directly.
Physical, chemical and biological parameters must be considered for this category.
Exposure effect and route of substances should be concerned. Toxicity studies are referred to
and occasionally toxicity test is carried out.
6.7 Commercial and sports fishing / aquaculture
Bio-accumulation and bio-magnifications of substances, which affect to human health through
food chain, are considered in this category.
Poor water quality results in loss of production of culture species and worse quality of processed
goods.
Special consideration might be necessary depending on the target species, because resistance
capability to substances is different for each species.
As toxicity and tolerance data is not available for all target species, representative species of
each group (finfish, mollusk and crustacean species) are chosen to evaluate the maximum
permissible concentrations.
6.8 Suspended particulate matter and sediment
This category is specified in some countries for dredged sediment from water body to be used
for soil improvement and for application to farmland. Other consideration is to protect
organisms living on/in sediment.
Persistent pollutants in sediments are accumulated and
biomagnified through aquatic food chains to grater concentrations in fish and fish-eating birds.
This category has not yet reached to an advanced stage, so only a few criteria are available.
6.9 Industrial water
This category is mainly considered for industrial plants.
Ambient water, which is used for the
plant, should not damage the plant, such as degradation of water pipes, clogging of water filter,
etc. Phytoplankton bloom is frequently the origin of clogging of water filter.
In that sense, basic parameters such as pH, suspended solid, Total Nitrogen and Total
Phosphorus are considered for this category.
19
6.10 Others
Other than consideration described above, the following information should be collected to
cover all necessary consideration for establishing criteria.

Types, estimated used amount, production amount, imported amount of pesticides and
herbicides used now.

Types, estimated used amount of pesticides and herbicides used in the past.

Types, estimated used amount of persistent pesticides and herbicides.

Measured concentrations of pesticides and herbicides mentioned above in ambient
water.

Above information on pesticides and herbicides will be referenced when selecting PFC
after prioritizing by behavior in the environment, influence to human health, and eco
toxicity.

Industry factors such as industry type, characteristic, future plan and concentrations of
substances in the discharge.

Water treatment factor such as capacity and treatment method.

Chemical analysis factor such as equipment and capability

Administration factor such as regulation, inspection, guidance

Toxicity information and epidemiological survey results on chemical substance by
international organizations and major countries protecting the environment.

Latest guidelines, standard and criteria of international organizations and major
countries protecting the environment.

Social factors such as population, major industry and its future plan.

Water statistics such as volume of used water

Ambient water quality, monitoring results

Fauna and flora of aquatic life, especially commercial and endangered species

Actual state of violation against criteria/standard
20
7. Consideration from various viewpoints to establish criteria
Based on the considerations, data and information mentioned in the above section, criteria
parameters are selected and their concentrations are determined.
This section discusses those procedures from various points of view.
Necessary procedures to be checked are listed in Appendix 1.
7.1 Industrial effluent
(1) Discharged water
Several kinds of discharged water are considered in the environment as follows.
a. Municipal wastewater
Sewerage is discharged from houses, restaurants and hotels. This usually contains
substances related to living environment such as BOD, COD, suspended solids, nitrogen,
phosphorous, Coli forms and so
on.
b. Industrial wastewater
Topic 6: Regulation for sewerage
water in Mexico
This is discharges from
All towns with population higher than 2,501
factories.
inhabitants should comply with
Industrial effluent
should be treated before it is
NOM-001-SEMARNAT-1996, which
discharged into environment
regulate water quality discharged through
because it may contain not only
treatment plant, as of the 1st of January,
parameters for living
2010 and the towns with less than 2,500
environment but also
inhabitants will not have to comply with it.
parameters for human health
such as heavy metals and
organic compounds.
c. Livestock wastewater
Livestock houses also discharge wastewater.
It contains feces and urine from stocks as
well as food remaining.
d. Natural drainage water
Natural drainage water includes precipitation, rainwater drainage from urban area, from
farm land and from forests. Natural drainage water includes some contaminants.
(2) Importance of treatment
21
In general, treatment of water before discharge is
ideal.
Topic 7: Coverage
percentage in
Mexico
Wastewater from houses, hotels and restaurants in
urban area is often collected through sewerage
system and is lead to treatment facility managed by
85% of the municipal
municipalities.
wastewater generated
Septic tank or individual treatment system is used
through the sewer
in rural and unpopulated area. The installation of
systems is being
the facility is usually regulated.
collected, while 32.6% of
the municipal waste
Effluent from factory is also expected to be treated
water is treated. Also,
before discharge and it is often regulated.
only 15.8% of the
Untreated effluent, however, is sometimes
generated industrial
discharged due to financial problem of the facility
wastewater is being
and insufficient regulation system.
treated (188.7 m3/seg)
Environmental impact by industrial effluent is
(data from 2007)
usually great because it often contains a lot of
contaminants such as heavy metals, organic
compounds and its discharging volume is big.
For establishment of water quality criteria, the recognition of current situation of industrial
effluent and the importance of treatment is fundamental.
It is very important to determine WQC considering wastewater treatment technology.
Improvement of water treatment technology influences the ambient water directly.
The
more advanced technology for water treatment, such as ion exchange treatment,
semi-permeable membrane, nano-filtration or particular absorbing agent which is expensive,
the more environmental situation is improved.
This means industries have to take on
greater financial obligation. On the other hand, it is also necessary to consider protection of
industries.
Industrial wastewater must be treated more cheaply so as not to negatively
impact management of manufacturers.
From that point of view, MPC of some PFC might be set as tentative value, considering the
balance between the situation of water-treatment technology and the environmental situation.
In that case, MPC of the parameters should be revised regularly (preferably every 5 years),
considering the situation of improvement of water treatment technology and the
environmental situation based on regular monitoring.
(3) Selection of parameters and determination of criteria values
22
If standard or regulation for industrial effluent is existed, they should be evaluated and the
relationship between the regulation/standard and WQC must be considered before starting
selection of PFC.
Topic 8: Standards in Japan
Concentration of environmental water standard in Japan is set as
1/10 of the one of industrial discharge standard, considering
dilution rate by environmental water and based on the long-term
monitoring data.
The following topics are taken into consideration for the selection of parameters.
a. Selection of parameters
1)
Criteria for conservation of living environment
◆ Parameters for conservation of living resources
Drainage from living environment includes urban sewerage and effluent from septic
tank.
Parameters for conservation of living environmental water are considered below.
pH, BOD, COD, SS, DO, N-hexane extract, Coli form bacteria, T-N, T-P
◆ BOD and COD as environmental water quality criteria
Organic materials are not always toxic to the water environment.
If a water body has
enough dissolved oxygen, organic materials are decomposed to final product, water or
carbon dioxide gas, which are generally harmless. But excess of organic materials that
consume much more dissolved oxygen on decomposition of organic materials and that
leads to anaerobic conditions.
Also, harmful substances such as methane gas or
hydrogen sulfide, which doesn’t contain oxygen within its molecules, are produced.
Water contamination is defined as such condition. BOD, therefore, is recommended to
be applied as a parameter of environmental water criteria that indicates the level of
dissolved oxygen, while COD is applied in lakes based on the following reason.
The speed of water flow in lake and sea is slow. Also, plankton and algae are suspended,
which consume dissolved oxygen.
Therefore it is better to apply COD which use
chemical oxidative decomposition of organic materials.
23
2)
Parameters for protecting human health
◆ Parameters for protecting human health are recommended as follows:
Cadmium, Cyanogens, Organic Phosphorous compound, Lead, Chromium,
Chromium Hexavalent, Arsenic, Mercury and compound, Alkyl Mercury
compound, PCB, Organic Solvent, Pesticides
b. Determination of criteria value
It is very important to figure out water balance of each watershed. Water resource
availability means total amount of surface water and ground water of each watershed. It is
calculated as follows:
Amount of water (surface + ground) = Total precipitation – Amount of
evaporation = Water resource availability
(5.1)
The total amount of discharged water of each watershed must be estimated. (See Sub-sub
section 7.1 (1) for the details of discharged water)
Water resource availability (A), amount of discharge (D), effluent standard value (S) and
environmental water criteria value (V) have a relationship in the same watershed as
shown in following equation.
V/S ≅ D/A
(5.2)
Flowing water like a river has its own self-purification function.
It is very difficult to
estimate the self-purification function of each watershed because each watershed has a
different water environmental situation. Therefore self-purification function of each
river is not considered in this equation.
(4) Strategic consideration
For more effective improvement of water environment, the following elements are
considered as management strategy.
a. Revision of WQC
Criteria should be revised regularly (ideally every 5 years), based on the monitoring data
and current understandings.
b. Revision of effluent standard
As QWC must be closely related to effluent standard, revision of effluent standard should
be included upon revision of WQC.
24
c. Inspection system for industrial effluent
In case a manufacturer violates the effluent regulation, it is common to pay a penalty.
Alternative penalty should be considered such as suspension of wastewater discharge,
stopping business or even criminal trial.
d. Promotion of construction/improvement of sewerage treatment plants
The coverage of sewerage treatment must come close to the coverage of sewage pipe
connection in order to improve the water environment. Otherwise untreated water will
keep discharging.
Installing sewer pipe without connection to a treatment plant will
cause a bad water environment.
e. Improvement of treated water quality
Existing treatment process should be revised to contribute to improve the water
environment.
Extension of existing treatment plant to add new treatment-processing
plant is an alternative.
7.2 Toxic substances
(1) Introduction
In order to prevent any negative effects caused by chemical substances that are potentially
hazardous to human health and the ecosystem, it is important to quantitatively evaluate the
environmental risk of these substances. The identification of danger is the first step of the
risk assessment, and in case water pollution is established because of the presence of
dangerous substances, identifying the toxicity of the chemical substance to human health
and the ecosystem should be done, as described below.
(2) Toxicity assessment regarding the protection for human health
Toxicity assessment involves the determination of what negative health-effects might be
caused by exposure to chemicals. Toxicity data of each targeted chemical substance,
which shows at what level potential harmful effects may begin to occur, are obtained.
a. Hazard identification
Hazard identification covers the types of adverse health effects that can be caused by
exposure to some substances in question, through the characterization of the quality and
weight of supporting evidence.
b. Dose-response assessment
25
A dose-response relationship describes the correlation between the likelihood and
severity of adverse health effects (the responses) and the amount and condition of
exposure to a toxic substance (the dose provided).
In order to conduct the risk judgment of the involved substances and to determine MPC
of PFC for WQC, information such as TDI or NOAEL (No Observed Adverse Effect
Level) / LOAEL (Lowest Observed Adverse Effect Level) for threshold chemicals and
the cancer potency factor for non-threshold chemicals should be obtained through
dose-response assessment, as described in Sub sub-section 7.2 (2).
(3) Toxicity information
In order to evaluate the toxicity and the risk that allows prioritization of the substances
and to derive MPC of PFC, information as well as toxicity data should be summarized.
Table 5 shows example contents of a factsheet. All information necessary for the risk
assessment should be kept in a database and regular update is recommended.
Table 5 Contents of Factsheet for Risk Assessment
1
General description
CAS Number, Formula, Physicochemical properties, Major uses,
Production and consumption, Environmental impact
2
Analytical methods with quantification/detection limits
3
Toxicological review
4
Environmental levels and human exposure
5
Monitoring levels in water basins in Mexico
6
Criteria and guideline values
6.1 National criteria, standards and guidelines
6.2 WHO, USEPA, EU, Japan
7
MPC derivation and priority grouping in Mexico
8
References
Topic 9: Example of Factsheet
In the Project, table shown in Attachment 3 (e.g Cadmium) was
prepared as a factsheet to easily access the source data for risk
assessment.
26
Collection of the toxicity information should be conducted by literature survey.
As
reliable toxicity information on human health, the following web sites should be
regularly examined. The point to keep in mind is that MPC of PFC for the human
health protection is determined based on chronic toxicity.

WHO: Chemical hazards in drinking-water
http://www.who.int/water_sanitation_health/dwq/chemicals/en/index.html

International Agency for Research on Cancer (IARC)
http://monographs.iarc.fr/ENG/Classification/index.php

USEPA: IRIS (Integrated Risk Information System)
http://cfpub.epa.gov/ncea/iris/index.cfm
7.3 Risk assessment
(1) Risk assessment
Risk assessment is used to characterize the nature and magnitude of health risks to humans
and ecological receptors from chemical contaminants and other stressors in the
environment.
Figure 5 shows a general risk assessment flow.
Information derived from risk assessment can be used to select the parameters for water
quality criteria and their maximum permissible concentrations.
In this and in the following sections, the procedures and methods for human health risk
assessment and ecological risk assessment are described.
27
Environmental
monitoring
Emission and
source (PRTR)
Ambient
concentration
Toxicity test
(Dose-response)
information &
Guidelines
Dose estimation of
exposure from products
Estimation of exposure to
human & environment
Toxicity
assessment
Exposure
assessment
Initial risk assessment
(Risk judgment)
Detailed risk
assessment
Figure 5 Risk Assessment Flow
(2) Risk assessment procedure for selection of PFC of WQC and determination of MPC
Risk assessment procedure for selection of PFC of WQC and determination of their MPC is
depicted in Figure 6. In a toxicity assessment, toxicity data of targeted substances, such as
dose-response relationship, is obtained. In an exposure assessment, exposure of toxic
substances to human and aquatic life is estimated, based on the ambient concentration of
toxic substance in water body.
Risk assessment involves the integration of the exposure
and toxicity assessment.
At the initial risk assessment stage, parameters for criteria are selected and prioritized,
considering:
•
Toxic Risk level of chemical contaminants, for example, carcinogenic potential.
•
Substance that by its physical-chemical characteristics and environmental distribution
are considered as International concerns, for example, POPS.
•
Geophysical and socio-economic circumstances of the country.
28
Toxicity assessment
1. Development of the PFC list
2. Collecting information on toxicity and epidemiological data of PFC
Exposure assessment
3. Collecting information on nationwide monitoring data
4. Collecting information on emissions and sources
5. Estimate human exposures and their routes
Risk characterization/ judgment
6. Screening process combined the toxicity and exposure assessment
to select the priority toxic pollutants in the country
Develop MPC of PFC for human health protection
7. Review the risk assessment methods
8. Derive the MPC of PFC for human health protection
Figure 6 Risk Assessment Procedure for Determination of MPC of PFC
(3) Development of the list for PFC of WQC
WHO produces international norms on water quality and human health in the form of
guidelines that are used as the basis for regulation and standard setting.
The WHO Guidelines for Drinking-water Quality are kept up-to-date by a rolling revision.

Check: http://www.who.int/water_sanitation_health/gdwqrevision/en/index.html
Therefore, selection of some PFC of WQC matches with the WHO guidelines for drinking
water criteria.
As shown in Figure 7, a tentative table should be compared to other
national criteria, such as those published by the USEPA and EU, and parameters
introduced if necessary.
The parameters should also be compared to current water-related-national-norms 1.
Check should also be made of the parameters most frequently published in PRTR
(Pollutant Release and Transfer Register)2.
1
Such as NOM-127-SSA1-1994 and NOM-001-ECOL-1996. See Box a in the case of Mexico.
2
RETC (Registro de Emisiones y Transferencia de Contaminantes) in Mexico.
29
Pesticides and other hazardous chemicals that have not been used for a long time in the
country should be removed from the PFC list.
As commented in Section 7.2, information regarding toxicity assessment should be used
for development of the list for PFC of WQC. Toxicity information such as dose-response
relationship for candidate parameters should be documented for reference.
WHO table of chemicals: health significance in drinking water
Compare to other countries’ WQC
Check whether parameters in NOMs are on the
Check whether parameters in PRTR (discharge
to water body) are on the list
Remove pesticide that are not used in the country
Tentative PFC for human health protection
Figure 7
Risk Assessment Procedure for Determination of MPC of PFC
(4) Exposure assessment
The purpose of exposure assessment is to estimate total exposure to a targeted substance.
An example of human exposure is described in Table 6.
To estimate the exposure, the following information should be collected:
a. Monitoring data of ambient water quality
Monitoring data is needed to check the level of pollution and to estimate the exposure.
When nationwide monitoring data seems to be insufficient, information from any
monitoring campaign can be used3.
b. Substances reported in PRTR
When monitoring data is missing, ambient concentration can be estimated by using
emission and discharge data reported in PRTR.
3
Classification Studies on specific water bodies have been conducted for 17 water bodies.
30
c. Criteria for the environmental quality and food safety
Parameters and their permissible limits should be checked in order to harmonize the
strategy for the integrated watershed management.
Since there are several exposure routes as shown in Table 6, criteria relevant to human
exposure regarding the control of toxic residues in food should be taken into
consideration.
d. Pesticides
When monitoring data of pesticides in a water body is insufficient, taking into account
their bioavailability and biodegradation, ambient concentrations can be estimated by
using actual consumption.
It is better to look at NOMs and regulations related to prohibition and limitation of
pesticide use in the country.
Table 6 shows the calculation of total exposure which is multiplying the concentration
by the consumption and summing up the exposures of all routes.
Table 6 Estimate of Total Exposure
Concentration
Type of exposure
Amount
(Example of Japan)
Tap water
c (μg/L)
3
Consumption
2 L/day
Inhalation
15 m3/day
0.15 g/day
Air
c (μg/m )
Soil
c (μg/g)
Intake
Food
c (μg/g)
Ingestion
Fish:
120 g/day (Japan)
17.5 g/day (USA)
Total exposure
∑ (concentration * amount) / human body weight
(μg/day/kg)
(5) Risk judgment
Simplified Risk judgment compares estimated human exposure (EHE) with Tolerable
Daily Intake (TDI).
TDI is derived from the toxicity assessment as explained in Section
7.2 (7).
Estimated human exposure is derived from the exposure assessment as mentioned above.
31
If EHE is greater than TDI as shown in Figure 8, control measures are needed to reduce
the risk. If they are close, it is better to set up a limit and to keep monitoring it.
On the other hand, when estimated human exposure is much lower than TDI, there is
tolerable risk at that time.
Risk judgment? comparison
Estimated human
exposure ∑(sum)
Tolerable
daily intake
Figure 8 Risk Judgment
(6) Priority of categorization based on the risk judgment
PFC of WQC for human health criteria can be categorized into four groups based on the
priority from the point of view of country’s environment as follows:
a. Priority 1: Prior PFC to be controlled
Substances of higher risk level which are observed in water bodies. Internationally
recognized toxic substances, such as POPs and new POPs, should be included.
b. Priority 2: PFC to be monitored
Substances in risk level which are observed in water bodies.
c. Priority 3: PFC to be measured
Substances which are not currently exceed the risk level but should be measured.
d. Others: PFC which are currently not possible to evaluate
Toxic data are not yet available but should be regularly checked for new information.
The procedure for categorization is explained after item “(7) Derivation of MPC of PFC for
human health protection” because the terminology and information of the risk assessment
will be used in derivation.
(7) Derivation of MPC of PFC for human health protection
According to how a toxic substance reacts, its effect is grouped in one of two categories for
the calculation of the respective MPC:
◆ Toxic effects with Threshold chemicals
◆Toxic effects with Non-threshold chemicals, chemical substances without threshold
(mostly genotoxic carcinogens)
32
According to WHO (2008), in deriving MPC for carcinogens, consideration was given to
the potential mechanism(s) by which the substance may cause cancer, in order to decide
whether a threshold or non-threshold approach should be used.
On the basis of the available evidence of long-term experimental animal studies, and on
epidemiological studies of human occupational or environmental exposure, IARC
categorizes chemical substances with respect to their potential carcinogenic risk into the
five groups as shown in Table 7. According to IARC, these classifications represent a
first step in carcinogenic risk assessment.
In establishing MPC, the IARC evaluation of
carcinogenic compounds can be taken into consideration.
Table 7 IARC Categories of Potential Carcinogenic Risk
IARC
Potential carcinogenicity
Reference: USEPA
Category 1
Carcinogenic to humans
Carcinogenic to humans
Category 2A
Probably carcinogenic to humans
Likely to be carcinogenic to humans
Category 2B
Possibly carcinogenic to humans
Suggestive evidence of carcinogenic
potential
Category 3
Category 4
Not classifiable as to carcinogenicity
Inadequate information to assess
to humans
carcinogenic potential
Probably not carcinogenic to humans
Not likely to be carcinogenic to humans
a. Chemicals with a Threshold for non carcinogenic toxic effect
For most kinds of effects from toxicity from known substances, it is believed that there
is a “threshold” dose below which no adverse effect will occur as shown in Figure 9.
For chemicals that give rise to such toxic non carcinogenic effects, a tolerable daily
intake (TDI: mg/day/kg) is derived as shown in Equation 7.1.
TDI 
NOAEL or LOAEL
UF
(7.1)
where:
• NOAEL= No Observed Adverse Effect Level (mg/day/kg)
• LOAEL= Lowest Observed Adverse Effect Level (mg/day/kg)
• UF
= Uncertainty Factor (-)
MPC (mg/L) can be then derived from TDI as shown in Equation 7.2
33
MPC 
TDI  bw  P
DI
(7.2)
where:
• bw = Body weight (kg)
(WHO default : 60 kg adult)
• P = Fraction of the TDI allocated to drinking-water (-)
• DI = Daily drinking-water consumption (L/day) (WHO default: 2L/day)
Response (probability)
Dose-response curve
Death
Toxication/
Adverse
Dose
physiclogical
UF
TDI
Threshold value
(=endpoint)
Figure 9
Threshold chemicals
In Equation 7.2, the relationship shown in Table 8 should be kept in mind.
The values
of these parameters should be determined on the basis of standards in the country
obtained from recorded values averaged from national statistics.
Table 8 MPC and Parameters in Equation 7.2
Lower <=
MPC
=> Higher
lighter <=
bw
=> heavier
smaller <=
P
=> bigger
Uncertainty
Guidelines are
factors of WHO
more
<=
DI
34
=> less
shown in Table 9.
Table 9 Source of Uncertainty in Derivation of Guideline Values
Source of uncertainty
Factor
Interspecies variation (animals to humans)
1–10
Intraspecies variation (individual variations within species)
1–10
Adequacy of studies or database
1–10
Nature and severity of effect
1–10
(WHO Guidelines for Drinking-water Quality, 2006)
For example, the uncertainty factor 100 is applied to the NOAEL derivation from the
principal animal study: 10 for consideration of intra-species variation, and 10 for
consideration of interspecies extrapolation.
UF = 100 (= 10 x 10)
b. Non threshold chemicals
According to WHO (2008), in the case of compounds considered as genotoxic
carcinogens (Group 1) or probable human carcinogens (Group 2A), mathematical
models are generally used to determine the guideline values of cancer risk when
exceeding the upper limits (OMS, 2008). Although several models exist, the lineal
multilevel model is generally adopted (USEPA, 2000). In certain cases, other models are
considered the most appropriate.
These models compute an estimate of risk at a particular level of exposure, including
upper and lower bounds of confidence on the calculation, which may include zero at the
lower bound. Conservatively, MPC is presented as the concentrations in drinking-water
associated with an upper-bound of the excess lifetime cancer risk of 1 x 10-5 (or one
additional cancer per 100,000 of the population ingesting drinking-water containing the
substance at the guideline value for 70 years). Each country may consider that a different
level of risk is more appropriate to their circumstances, and values relating a range of
10-4 or 10-6 may be determined by respectively multiplying or dividing the guideline
value by 10 (WHO, 2008).
The mathematical models used for deriving guideline values for non-threshold
chemicals cannot be verified experimentally. Therefore they assume the validity of a
linear extrapolation of very high dose exposures in test animals to very low dose
exposures in humans. As a consequence, the models used are conservative (WHO,
2006).
35
MPC for the non threshold chemicals is calculated by Equations 7.3and 7.4. First, a
risk-specific dose is obtained by Equation 7.3.
RSD 
Target Incrementa l Cancer Risk
m
(7.3)
where:
• RSD = Risk-specific dose (mg/kg-day)
• Target Incremental Cancer Risk = Value in the range of 10-6 to10-4
• m = Cancer potency factor (per mg/kg-day) = Slope factor as shown in Figure 10.
(USEPA IRIS web: http://cfpub.epa.gov/ncea/iris/index.cfm)
Then, MPC is obtained from Equation 7.4.
MPC 
RSD  P  bw
DI
(7.4)
Low-dose linear
extrapolation
(=Point of Departure)
Slope m
Figure 10 Cancer Potency Factor (Slope Factor: m)
(8) Procedure to determine the priority group
The procedure based on the risk judgment explained above can be used to determine the
priority group of PFC. There are two assessment methods to assess the risk level of the
human exposure.
However, derivation of EHE based on the information described in
Table 6 might be difficult due to the lack of data based on the national survey and/or
national monitoring.
In this case, a simplified method can be used for the priority
grouping.
36
a. Hazard Quotient
Hazard Quotient (HQ) is derived from EHE divided by TDI as shown in Equation 7.5.
HQ  EHE TDI
(7.5)
If HQ ≥ 1, then the substance of concern is in risk level and classified into Priority 1 and
Priority 2 groups.
If HQ < 1, the substance of concern is not in risk level and classified into Priority 3
group.
37
Topic 10: Example of USEPA (USEPA, 2000)
USEPA uses the following equations for deriving AWQC (ambient water quality criteria), i.e.,
national recommended water quality criteria.
Non-cancer effects
AWQC  RfD  RSC 
BW
4
DI   (FIi  BAFi )
i 2
Cancer effects: Nonlinear Low-Dose Extrapolation
AWQC 
POD
 RSC 
UF
BW
4
DI   (FIi  BAFi )
i 2
Cancer effects: Linear Low-Dose Extrapolation
AWQC  RSD 
BW
4
DI   (FIi  BAFi )
i2
where:
RfD = Reference dose for noncancerous effects (mg/kg-day)
POD = Point of departure for carcinogens based on a nonlinear low-dose extrapolation
(mg/kg-day), usually a LOAEL, NOAEL, or LED10
UF = Uncertainty Factor for carcinogens based on a nonlinear low-dose extrapolation
(unitless)
RSD = Risk-specific dose for carcinogens based on a linear low-dose extrapolation
(mg/kg-day) (dose associated with a target risk, mainly 1 X 10-6)
RSC = Relative source contribution factor to account by source, which represents exposure
proportion to the substance by sources that are not water consumption and fish from the water
body of interest. (Not used for linear carcinogens.) May be either a percentage (multiplied) or
amount subtracted, depending on whether multiple criteria are relevant to the chemical.
BW = Human body weight (default = 70 kg for adults)
DI
= Drinking water intake (default = 2 L/day for adults)
FIi
= Fish intake at each trophic level (TL) I (I = 2, 3, and 4) (defaults for total intake =
0.0175 kg/day for general adult population and sport anglers, occasional consumers and 0.1424
kg/day for subsistence fishers, subsistence consumers). For the general adult population and
sport anglers are: TL2 = 0.0038 kg/day; TL3 = 0.0080 kg/day; and TL4 = 0.0057 kg/day.
BAFi = Bioaccumulation factor at trophic level I (I=2, 3 and 4), lipid normalized (L/kg)
38
b. Margin of Exposure
Margin of Exposure (MOE) is derived from NOAEL divided by EHE as shown in
Equation 7.6.
MOE  NOAEL EHE
(7.6)
If MOE ≤ UF, then the substance of concern is in risk level and classified into Priority 1
and Priority 2 groups.
If MOE > UF, the substance of concern is not in risk level and classified into Priority 3
group.
c. Simplified method for the priority grouping
The priority grouping of PFC can be done by deriving from the Priority Factor (FP)
defined as follows:
FP  CA GV
(7.7)
where:
• CA = Actual annual average concentration observed at nationwide monitoring
stations (mg/L)4
• GV =MPC: Maximum Permissible Concentration (mg/L) derived from Equation 7.2
(USEPA: GV corresponds to AWQC, Topic 10)
According to the magnitude of FP, PFC can be classified into four groups as shown in
Table 10.
4
For instance in Mexico, data from the National Monitoring Network of heavy metals
and the Classification Studies for 17 water basins can be used for CA.
39
Table 10 Priority Grouping for PFC of WQC for Human Health
Priority
Priority
group
Factor
Group 1
FP ≥ 1
Group 2
0.1 ≤ FP < 1
Group 3
FP ≤ 0.1
Others
-
Description
PFC of higher risk level which are observed in water
bodies.
PFC in risk level which are observed in water bodies
PFC which are not currently exceed the risk level but
should be measured regularly
Toxic data are not yet reliable but should be
regularly check the new information
Topic 11: Priority Grouping: Example in Japan
For example in Japan, the priority grouping is conducted as follows:
1) Obtain the annual average concentration for a target substance at each monitoring
station: CA
2) Compare CA with MPC at each monitoring station, and figure out the number of
stations of:
A)
CA  MPC
B)
CA  0.1 MPC
3) Grouping according to the conditions of A) and B)
(1) Priority 1 (standards)
If there exists any station meets the condition A) and several percent of
monitoring stations meet the condition B), then the substance shall be assessed
whether it must be in Priority 1.
(2) Priority 2 (guideline values)
If there exists any station meets the condition B), then the substance shall be
assessed whether it must be in Priority 2.
40
7.4 Conservation of aquatic life
Figure 11 shows the protocol for deriving water quality guideline for protection of aquatic life
by Canada (Canada, 1999). This manual basically follows the protocol.
Source: CCME (1999)
Figure 11 Protocol for deriving water quality guideline
The guideline value for the aquatic life is derived by applying an appropriate assessment factor
to the toxicity test data that uses a species in a growth stage, which is the most sensitive period
to the target chemical.
Figure 12 shows a flowchart of the procedure to obtain a guideline value.
Details of each procedure are described in the following sections.
41
Search for toxicological data
See (1)
Evaluation of toxicological data
See (2)
Selection of the most sensitive
toxicological data
See (3)
EC50 or LC50
LOEC or NOEC
Determination of the
assessment factor
Only one L(E)C50
Assessment
factor: 1000
Determination of the
assessment factor
More than one L(E)C50s
Assessment
factor: 100
One or more N(L)OECs
Assessment
factor: 10
Derivation of the guideline value
See (5)
Approval and periodically review
See (6)
LC 50: 50% Lethal Concentration, Concentration in which 50% of target species dies.
EC50: 50% Effective Concentration, Concentration in which 50% of target species is
influenced.
NOEC: No Observed Effect Concentration, Concentration by which no influence to the target
species is observed.
LOEC: Low Observed Effect Concentration, The lowest concentration by which influence to
the target species is observed.
Figure 12
Assessment Procedure for WQC
42
See (4)
(1) Search for toxicological data
In the first step, it is necessary to collect as much toxicological data regarding the target
chemical as possible.
It is preferable to collect the toxicological data from each taxonomic group in the food
chain of the aquatic ecosystem such as algae, crustaceans, and fishes, because the response
mechanism to toxicity of the chemical is expected to change depending on the difference of
taxonomic group or species.
As data sources, several databases or various literatures regarding the eco-toxicology are
available. The databases that accumulate a lot of information regarding the toxicity of
chemicals for the aquatic life are maintained by USEPA, OECD, EU, etc. Among these
databases, ECOTOX (The ECOTOXicology database) by USEPA contains many kinds of
single chemical toxicity data. At the time of June 24, 2009, total number of chemicals, test
species, and test data that registered in ECOTOX database are 9094, 8607, and 650564
respectively.
Table 11
Sources for Toxicological Data
Database of toxicological data
Database Name
Administrator
URL
ECOTOX
USEPA
http://cfpub.epa.gov/ecotox/
SIDS
OECD
http://www.chem.unep.ch/irptc/sids/oecdsids/sidspub.html
eChemPortal
OECD
http://webnet3.oecd.org/echemportal/
ESIS
EU
http://ecb.jrc.ec.europa.eu/esis/
Chemical Assessment Report
Report Name
Administrator
URL
Canadian Water
Quality
Guidelines for the
Protection of
Aquatic Life,
Factsheets
Priority Existing
Chemical
Assessment
Reports
CCME
http://ceqg-rcqe.ccme.ca/
NICNAS
http://www.nicnas.gov.au/publications/CAR/PEC.asp
Retrieval
Software Name
Pub-Med
Administrator
URL
USNLM
http://www.ncbi.nlm.nih.gov/pubmed/
TOXNET
USNLM
http://toxnet.nlm.nih.gov/index.html
Literature
Google Scholar
http://scholar.google.com/
43
(2) Evaluation of toxicological data
It is necessary to evaluate whether the data obtained is acceptable or not, because the data
might have low reliability. Evaluation of toxicological data should not follow a rigidly
fixed format, but should be based on scientific judgment and occasionally special
consideration is necessary.
Upon data retrieval from toxicological database, the following information is crucial for
evaluation purposes:

Test condition/procedure (e.g. static, semi-static, flow-through, etc.)

Concentrations of the test substance in the test solutions

Test species (e.g. scientific name, strain, life stage, body size, any pretreatment,
etc.)

Water quality characteristics (pH, hardness, temperature, dissolved oxygen
concentration) - Hardness of the water used for toxicity test of the metal must be
measured, because hardness is one of the factor that strongly influences the
expression of toxicity of the metal.

Chemical characteristics of the test substance (e.g. solubility, persistence, Log
Pow: Octanol/water Partition coefficient as logarithm, etc.)
In case data from chemical assessment report or literature is referred to, the following
points should be noted in evaluating the toxicity data:

Toxicity tests must be executed according to the authorized test guideline (e.g.,
guidelines published by USEPA, OECD, and EU).

As a minimum requirement, various concentrations of test solution must be
measured at the beginning and end of the exposure period.

Generally, static tests are unacceptable unless the result shows that various
concentrations do not change during the test and adequate environmental
conditions for the test species are maintained.

Preferred endpoint in partial or full lifecycle test includes determination of effects
on embryonic development, hatching or germination success, survival of juvenile
stages, growth, reproduction and survival of adults.

Response and survival of target species in the control test must be measured and
should be appropriate for the life stage of the test species used.

Measurements of non-biotic variables such as temperature, pH, dissolved oxygen,
and water hardness should be reported so that any factors that may affect toxicity
can be included in the evaluation process.
44
(3) Selection of the toxicological data
Only one toxicity data is selected from the collected toxicity data used to calculate the
guideline value. The standard for the selection is divided into three ranks as shown in
Table 12.
Toxicity data that should be selected as the first priority level is the most sensitive no
observed effect concentration (NOEC) or the lowest observed effect concentration (LOEC)
obtained from chronic test.
When the data of these types is not available, using the most sensitive median lethal
concentration (LC50) or median effective concentration (EC50) obtained from the acute
test can be considered.
If acceptable data doesn't exist, determination of guideline value for the target substance
should be suspended due to insufficient available data at the time.
Table 12 Standard for Selection of Toxicological Data
Rank
Data type
First priority
The most sensitive NOEC or LOEC from chronic test
Second priority
The most sensitive LC50 or EC50 from acute test
Unacceptable
In case toxicity data doesn't exist or all collected data is not
appropriate to be used for the guideline value.
The distinction between acute toxicity and chronic toxicity is defined in Table 13.
Table 13 Definitions of Acute Toxicity and Chronic Toxicity
Test
Acute Toxicity
Chronic Toxicity
Organism
Test Period
Endpoint
Test Period
Endpoint
Algae
72-96 hours
EC50
>72 hours
NOEC
Daphnids
>48 hours
LC50, EC50
>14 days
NOEC
Fish
>48 hours
LC50, EC50
>14 days
NOEC
(4) Determination of the assessment factor
The assessment factor is a kind of safety factor which is used when no effect concentration
in the real environment is estimated from toxicity test data. The assessment factor should
be set as more sensitive when data for many species is available or the test period is long as
45
like chronic test, because many kinds of species are exposed to the chemicals in the real
environment for a long term.
The assessment factor adopted by OECD is used in this
manual, while different factors are used in OECD, USEPA, and EU.
Table 14 Assessment Factors for Determining Guideline Value of WQC
OECD
USEPA
EU
Canada
(1998)
(1993)
(1999)
(1999)
One acute L(E)C50 from one
species among three trophic levels
(fish, crustacean and algae)
1000
1000
-
-
More than one acute L(E)C50s
from each of three trophic levels
100
100
1000
100
One chronic NOEC from one
species among three trophic levels
(fish, crustacean and algae)
100
10
100
10
Two chronic N(L)OECs from
species representing two trophic
levels (fish and/or Daphnia and/or
algae)
100
10
50
10
Chronic N(L)OECs from at least
three species representing three
trophic levels
10
10
10
10
Furthermore, it is necessary to apply larger assessment factor when the substance is
categorized in the following types;

High hydrophobicity; Log Pow is more than 4.

High bio-concentration; BCF is more than 500.

High persistence; aqueous degradation half-life time is more than 2 months.
Log Pow: Octanol-Water Partition Coefficient,
Pow is a concentration ratio of the chemical in each phase when achieving
the state of equilibrium after adding the chemical in two solvent phases of
1- octanol and water. Pow is used as a physicochemical index that
shows the hydrophobic property of the chemical (melting easiness to the
lipid), and described generally in logarithm value (log Pow).
It is known
that bio-accumulation in the organisms of the chemical often correlates to
the hydrophobic property of the chemical.
BCF: Bio-concentration Factor,
Bio-concentration factor is the concentration of a particular chemical in a
tissue per concentration of chemical in water. This physical property
46
characterizes the accumulation of pollutants through chemical partitioning
from the aqueous phase into an organic phase, such as the gill of a fish.
(5) Derivation of the guideline value
The guideline value is derived from selected toxicity data and assessment factor using the
following formula:
The most sensitive toxicological data
Guideline value
=
Assessment factor
47
Topic 12: Example of derivation of the guideline value
The derivation process of the guideline value was executed for the five substances (Benzene,
Cyanide, Lead, Phenol, and Styrene).
Relevant toxicological data was extracted from data
sources (Table A) and then the most sensitive toxicological data was selected from all data
after evaluation (Table B).
Table A Toxicity data obtained for derivation of guideline value
Substance
name
CAS
Number
Benzene
Cyanide
Lead
Phenol
Styrene
71-43-2
57-12-5
7439-92-1
108-95-2
100-42-5
A
x
x
x
x
Acute test data
C
F
x
x
x
x
x
x
x
x
x
x
Test organisms*
Chronic test data
O
A
C
F
x
x
x
x
O
x
x
*) A:Algae, C:Crustacean, F:Fish, O:Others
Table B The most sensitive toxicological data
Substance
name
Benzene
Cyanide
Lead
Phenol
Styrene
CAS
Number
71-43-2
57-12-5
7439-92-1
108-95-2
100-42-5
Test organisms
Fish
Mollusks
Crustaceans
Fish
Algae
Endpoint
96h-LC50
96h-LC50
7d-LC50
27d-LC50
96h-NOEC
Most sensitive
toxicological data
5.28 mg/L
0.0432* mg/L
0.001 mg/L
0.07 mg/L
0.063 mg/L
*) Exposure concentrations are clearly identified as nominal values or the author does not report
whether the concentrations were measured or nominal.
The guideline value is derived from the selected most sensitive toxicological data and
assessment factor using formula 7.4.6.
Table C Derivation of the guideline value
Substance
name
Benzene
Cyanide
Lead
Phenol
Styrene
CAS
Number
71-43-2
57-12-5
7439-92-1
108-95-2
100-42-5
Most sensitive
toxicological data
5.28 mg/L
0.0432* mg/L
0.001 mg/L
0.07 mg/L
0.063 mg/L
Assessment
factor
100
100
100
100
100
Guideline value
0.0528 mg/L
0.000432 mg/L
0.00001 mg/L
0.0007 mg/L
0.00063 mg/L
*) Exposure concentrations are clearly identified as nominal values; or the author does not report
whether the concentrations were measured or nominal.
48
7.5 Accuracy of chemical analysis
Chemicals, for which production/usage and discharge are recorded in the country, should be
prioritized by risk assessment based on their toxicity, discharge, production and the amount of
usage.
Also, highly prioritized chemicals must be measured in their ambient concentrations.
In this case, a sensitivity which satisfies the criteria value established based on toxicity, is
needed from the viewpoint of chemical analysis.
In other words:
The substances with higher toxic must be detected at the lowest concentration.
For this purpose, an appropriate method must be selected5 and the proper operation procedure
should be established respectively6.
In many cases, the summaries of the analytical methods
are introduced in the laws and ordinances of the environmentally-concerned countries.
However, an original arrangement and establishment of the quantification limit (herein after
referred as QL) based on the analytical condition of each laboratory is necessary7.
The ideal sensitivity of an analysis should be able to detect 1/10 of the criteria value based on
the toxicity.
With such sensitivity, it is possible to grasp a sign of environmental pollution and
set up additional administrative countermeasures.
5
Even though undesirable sensitivity is
For example, following methods are available for the analysis of heavy metals.
must be selected according to the required sensitivity.
And one of those
Generally, the lower method below shows the
higher sensitivity but requires a more expensive equipment.
Optical absorption spectroscopy
Atomic absorption spectrometry (AA)
- Flame AA
- Hydride generation AA
- Graphite furnace AA
Inductively-coupled plasma optical emission spectrometry (ICP-OES)
Inductively-coupled plasma mass spectrometry (ICP-MS)
6
Each laboratory possesses different instruments/equipment.
Also particular sample matrix (e.g.
sea water, sewage water, industrial effluent, etc.) might be analyzed.
Procedure must be established
to satisfy the required sensitivity in the various situations.
7
The QL is calculated based on the repeatability of the analysis results after establishment of the
procedure.
The QL varies slightly on each measuring batch, and difference of the QL between
laboratories is often observed.
To maintain the stable technical level is required in order to discuss
the cause of variations in ambient concentrations.
49
obtained, it is significant to carry out the environmental monitoring, especially when an
environmental degradation is considered by a specific substance8.
Environmental standard or effluent standard should be established by focusing on the
parameters, when their analytical methods have been established, because those occasionally
exceed the criteria values based on the toxicity.
It is also important to improve analytical
ability in order to ensure the desirable sensitivity of analysis.
Appendix 4 introduces a brief approach to establish analytical method and maximum
permissible concentration for criteria.
8
Establishing environmental standards as a temporal value using the QL, which shows higher value
than criteria value based on the toxicity, may sometimes lead to the improvement of ecosystem and the
conservation of human health.
50
Topic 13: Evaluation of quantification limit for Carbaryl
Draft MPC of Carbaryl is proposed as 0.0002 mg/L for conservation of aquatic life.
On the other hand, quantification limit (QL) of measurement was verified in
CONAGUA reference laboratory, and available instrument was HPLC/ultraviolet
detector. Target QL should be decided with reference to existing method, and the
target QL was tentatively proposed as 0.001 mg/L.
0.0005 mg/L as QL by using
HPLC/fluorescence detector was used as reference, although no report using
HPLC/ultraviolet detector was found.
Instrumental QL was evaluated based on repeatability of instrumental measurement
and was calculated as 0.051 mg/L.
However, 0.001 mg/L of the target QL could not
be achieved by simple 50 times concentration in sample preparation process.
Actually, approximate 0.001 mg/L of fortified Carbaryl was not recovered from matrix
samples, because of serious interferences and recovery loss.
To obtain the
satisfactory recovery rate, higher concentration (0.03 mg/L) of fortification was
necessary.
Experimental QL was evaluated based on the variance of parallel
measurements of matrix samples and was calculated as 0.027 mg/L.
Experimental QL value is finally the QL of the method.
Result of Verification for Carbaryl Analysis
Criteria value
(mg/L, tentative)
0.0002
Target QL
(mg/L, tentative)
0.001
Instrumental QL
(mg/L)
0.051
Sampling volume
1000 mL
Concentration rate in sample preparation
50 times
Sample corresponding Instrumental QL (mg/L)
0.00102
Experimental QL
(mg/L)
0.027
Recovery
(%)
51
93.3
This
7.6 Monitoring situation
Figure 13 shows work cycle management for revision of WQC.
As the figure shows,
environmental monitoring plays important role for the revision, to grasp current environmental
situation. (Also see the faint red-highlighted letters in Figure 1 at Page 4, Figure 2 at Page 5
and Figure 3 at Page 9)
In this section, consideration of environmental monitoring is discussed.
Strategy
Implementation
(e.g. licensing
and land use)
Government
Endorsement
Water Quality
Monitoring
Develop
Strategies
Environmental
Quality
Objectives
Do we
want to
change?
What does
it mean
and cost?
What have we
got?
What chances
have occurred
and why?
What do we
want?
How does
it differ
from what
we have?
Source: Australia and New Zealand (1998)
Figure 13 Work Cycle Management for Revision of WQC
To grasp current environmental situation, continuous monitoring is necessary from the
following viewpoints:
52
(1)
Obtaining statistic data
As each watershed has its own characteristics depending on the nature and the activities by
human beings (such as industries, households, land uses), statistic work and analysis based
on the monitoring data is necessary.
Accumulation of data is fundamental and regular and
sustainable monitoring is necessary.
Statistical analyses are used to identify variability in data and to elucidate relationships
among monitoring parameters. Simple descriptive analyses may be useful for initial data
analyses. The relationship between two variables may be of use in analyzing data for
criteria derivation.
Correlation and regression analyses allow the relationship to be
defined in statistical terms. (USEPA, 2000)
(2)
Identifying current water quality
Statistic data is used to grasp present situation of ambient water, whether it is maintained
well or not, comparing with previous data.
The following items may be confirmed as additional study:
- Contaminants discharged from industries
- Removal rate of certain contaminants by certain treatment techniques
53
Topic 14: Evaluation of monitoring data in Mexico
PFC for conservation of aquatic life was evaluated using environmental
monitoring data from the entire country, whether the target PFC is
appropriate to be selected based on the ambient situation.
Each target parameter is categorized into 4 priority levels using following
considerations:
Priority 1: Basic parameters, PEC/PNEC of the substance >100, POPs
Priority 2: PEC/PNEC of the substance >1, Substance of which monitoring
data doesn't exist though both of emission level and guideline
value for aquatic life is known, A part of POPs (Aroclor).
Priority 3: PEC/PNEC of the substance <1, Substance of which both of
monitoring data and emission level don't exist though guideline
value for aquatic life is known.
Priority 4: Substance of which data for judgment is insufficient.
Where:
PNEC (Predicted No-Effect Concentration): the maximum value among the
monitoring data of the target substance
PEC (Predicted Environmental Concentration): the minimum criteria/guideline
value for the aquatic life used in other countries/organization
If PEC/PNEC >1 then it is considered that the substance may give some
impacts to the aquatic life
(3) Evaluating the impact
Evaluation of impact by revising PFC or MPC is carried out to discuss necessity of further
revision of PFC or MPC.
Table 15 shows an example for assessing the current water quality against WQC.
54
Table 15 Comparison of Current Water Quality with WQC
Source: Australia and New Zealand (1998)
WQ equal to WQC
Maintain the WQC.
WQ better than WQC
Maintain the WQC.
WQ worse than WQC
Detailed work will be
required.
Weigh benefits of activities
Identify a range of feasible
that reduce the current
management options to
water quality while still
improve water quality to
maintaining quality at or
reach to the WQC
above the WQC.
WQ: Current water quality, WQC: Water Quality Criteria
Addition of new parameters, which are found in the monitoring or being studied in the
world, is also discussed.
55
Topic 15: Classification study in Mexico
The Declarations of Classification of the National Water Bodies are a technical and legal
instruments based on the Law of National Waters (LAN, Ley de Aguas Nacionales) which
will determine the following:

The parameters that the discharges should comply with

The dilution and assimilation capacity of the national water bodies

The contaminant loads which these bodies can receive

The quality goals for the water bodies and the discharges and the compliance terms.
To achieve above, procedures shown in the following figure are undertaken.
Water Body
Pollution
problem of the
water body
Establishment of CPDs
in discharge permits
Publication Official Gazette
Data Collection
Division of the Water Body into
sections
Selection of sampling and flow
measuring sites, monitoring
campaigns
Water quality
Hydrometric data
Wastewater treatment
Elaboration of Water Quality
Diagnosis
Water uses
Wastewater discharges
CNA Legal Dept
Consultation and
Acceptance by Basin
Council
Declaration of
Classification
Elaboration
scheme
for
Elaborationof
ofthe
Water
Quality
the Mathematical
Model
Diagnosis
Mathematical Model for Water
Quality
Procedures for the Study and Declaration of Classification in Mexico
(See Appendix 2 for the details)
56
References
A protocol for the derivation of water quality guidelines for the protection of aquatic life,
Appendix XI in Canadian Water Quality Guidelines, Canadian Council of Ministers of the
Environment (CCME), 1999
Administration for Water Environment in Japan, Japan Society of Water Environment, 1999
Australian and New Zealand guidelines for fresh and marine water quality, Australian and
New Zealand Environment and Conservation Council & Agriculture and Resource
Management Council of Australia and New Zealand, 2000
Charles E. Stephan, et al., Guideline for Deriving Numerical National Water Quality Criteria
for the Protection of Aquatic Organisms and Their Uses, USEPA
Guidelines for Ecological Risk Assessment, USEPA, 1998
Helmar, R.; Español, I. Water pollution Control -A Guide to the Use of Water Quality
Management Principles-, WHO/UNEP, 1997
Kohata K., Conservation of Water Environment and Establishment of Environmental Quality
Standard for Water Pollution in Public Water Area, Presentation material on the Seminar of the
Project on Capacity Enhancement for Establishing Mexican Norms of Water Quality Criteria,
2008
M. B. Pescod, Wastewater treatment and use in agriculture irrigation and drainage paper,
FAO, 1992
Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health
(2000), Technical Support Document, Volume 1: Risk Assessment, USEPA, 2000
Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health
(2000), USEPA, 2000
National Recommended Water Quality Criteria (2002), Human Health Criteria Calculation
Matrix, USEPA, 2000
57
National Water Quality Strategy - Implementation Guideline -, Agriculture and Resource Water
Management Council of Australia and New Zealand, Australian and New Zealand Environment
and Conservation Council, 1998
Nutrient Criteria Technical Guidance Manual -Rivers and Streams-, USEPA, 2000
Principles for Preparing Water Quality Objectives in British Columbia, Canada, 2001
Sustainable development strategy, United Kingdom,
http://www.defra.gov.uk/sustainable/government/
Terrence T. et al., Chemical safety of drinking-water: Assessing priorities for risk management,
WHO, 2007
Water Quality Standards Handbook - Second edition, USEPA, 1993
Water Quality Standards Program History, USEPA,
http://www.epa.gov/waterscience/standards/about/history.htm/
WHO Guidelines for Drinking-water Quality, Third Edition Incorporating the First and Second
Addenda Volume 1, Recommendations, WHO, 2008
58
Appendix 1
List of Necessary Considerations for Revising Criteria
1) Referred guidelines, standards and criteria parameters of international organization
such as WHO, major countries protecting the environment are the latest or not
2) Categorization of PFC (protection of health, conservation of ecology, water use) are
properly considered or not
3) Toxicity information of targeted chemical substances are collected and organized
enough
4) The difference of risk assessment approach in different countries are considered or not
5) The reality of use of targeted pesticides and herbicides
6) Target parameter’s effluent source, effluent amount, and their dynamics in watershed
7) Monitoring results of ambient concentrations and their change in years of time
8) Prioritization is conducted by considering 5) to 7) or not
9) Capability of water quality analysis in laboratories and monitoring ability in the field
are considered or not
10) Water resource, water use conditions, industrial structures/distributions are considered
or not
11) The criteria are linked to water pollution control regulations like effluent standards etc
or not
12) Categorization of criteria parameters are appropriate as a method of water quality
evaluation or not
59
Appendix 2
Declarations of Classification of the National Water Bodies in Mexico
As part of its attributions, CONAGUA issues permits for discharging wastewater into the
national water bodies (Article 9, Paragraph XX of the Law of National Waters (LAN, Ley de
Aguas Nacionales). These permits indicate the Particular Conditions for Discharging (CPD,
Condiciones Particulares de Descarga), which are a group of physical, chemical and biological
parameters, their corresponding maximum permissible levels allowed for wastewater discharge
for each user, in order to preserve and control the quality of the national water bodies.
Furthermore, Article 86, Paragraph IV of the LAN indicates that CONAGUA will be
responsible for establishing and watching over the compliance of the Particular Conditions for
Discharging, which should satisfy the wastewaters that are being poured directly into national
waters and properties.
On the other hand, Article 89 of this law mentions that CONAGUA, in order to issue the
discharge permits, it should take into consideration the Declarations of Classification of the
National Water Bodies as well as the Mexican Official Norms.
This way, the Declarations of Classification and NOM-001-SEMARNAT-1996 which
“Establish the Maximum Permissible Limits of contaminants in wastewater discharges into
national waters and properties” are the technical basis for CONAGUA to issue the discharge
permits in the national water bodies identified in the 5th Paragraph of Article 27 of the Political
Constitution of Mexico.
The Declarations of Classification are a technical and legal instrument that is based on Article
87 of the LAN establishing that CONAGUA will determine:

The parameters that the discharges should comply with

The dilution and assimilation capacity of the national water bodies

The contaminant loads which these bodies can receive

The quality goals for the water bodies and the discharges

The compliance terms.
60
The Declarations of Classification are applied to water bodies where the quality of the
wastewater being discharged is required as stricter than the one established in
NOM-001-SEMARNAT-1996 due to the low assimilation and dilution capacity of the receiving
body and when the discharges contain substances that are not being regulated by this NOM in
order to protect, recover a water use, and at the same time promote a long term multipurpose
use.
The Declarations of Classification are a product of a particular water quality study also called
Classification Study which is focused in determining the effect of the wastewater on the
receiving body with the use of mathematical models. The main objective is to have a technical
and legal tools that allow the regulation of the contaminating sources, so the water body could
reach a better quality in order to meet the requirements for one or several uses. The goals for the
water quality that are established in the Declarations of Classification for the water bodies are
based on the WQC, that are presently being updated by this Project, hence their importance.
The procedure for the elaboration of the Declaration of Classification of the national water
bodies is the following, which is simplified in the figure shown in Topic 15:
1. The process starts with the selection of the water body based on gathered information from
the National Water Quality Monitoring Network where the evaluation of such information
reflects that the water body contains high levels of contamination from specific sources The
evaluation is carried out using from two to five level indicators and the interval results will
classify it as highly polluted, as shown below:
(a).
BOD5 is higher than 120 mg/l.
(b).
COD is higher than 200 mg/l.
(c).
Suspended solids are higher than 400 mg/l.
(d).
Fecal coliforms are higher than 10,00 NMP/100ml.
(e).
Acute toxicity when Vibrio fischeri and Daphnia magna are larger or similar to
5 toxicity units.
In some cases, water bodies are selected which are classified with an excellent quality.
In this case, the purpose of the Declaration of Classification is to maintain and protect
the quality of the water body.
2. The water body is defined by sections or areas according to its type (river, dam, lake and
coastal zone), hydrographic and hydraulic characteristics, location of the specific
contamination sources and uses.
61
3. An extensive bibliographical revision of the evaluation area is carried out specifically of the
background studies and of the biophysical, population and service information, as well as of
the inventories for discharges and treatment plants.
General information is gathered
(hydrology, geology, topography, soil use, vegetation, fauna), as well as the hydrometric,
water quality, all the hydraulic infrastructure and sanitation as well as socioeconomic
information of the study area. The climate information (precipitation, pressure, altitude and
temperature. The historical information regarding water quality, sanitation, hydrometric,
storage levels and climate information should be at least from the last ten years, as well as
the economic activity (industrial sectors).
Data gathering is done in coordination with the
staff of CONAGUA from the Basin Organism and/or the corresponding regional office
from CONAGUA.
4. From the gathered information regarding:

the basin boundaries of the water body being studied and its hydrographic network,

location of the water quality monitoring network stations and hygrometry,

municipal and industrial wastewater discharges,

hydraulic infrastructure (dams), municipal wastewater treatment plant systems, and

the water resource uses,
a proposal is elaborated with the sampling and flow measuring sites for the study, as well as
a list of water quality parameters that will be evaluated.
All of this information is gathered
and represented as GIS and Web based topographical information service.
5. A prospective visit to the study area is carried out to verify the information mentioned in the
previous paragraph, in coordination with the local staff from CONAGUA as well as the
municipal and state offices that are related to water resource management. The number and
location of the sampling and flow measuring sites are selected in order to determine the
coordinates (UTM, geographical and decimals), including its altitude. The accesses to the
sampling and flow measuring sites are identified and then the time required for carrying out
the sampling and flow measuring activities is estimated.
6. The sampling and flow measuring jobs are carried out according to the plan elaborated
expressly for that and for each of the monitoring campaigns which include the following:

map of the study area with the location of the sampling sites and nomenclature,

list of sampling sites (code and name), list of parameters to be evaluated on field and in
the laboratory,
62

program of the works to be carried out in each site,

type of sample to be taken in each site (simple, compound, superficial), a program with
the delivery of samples to one of several laboratories, and

the name of the assigned sampling staff, number of brigades and the name of the
members with the activities to be carried out by each one, before, during and after the
field works,

list of materials, equipment (brand and model) with the reagents to be used (brand and
expiration date),

copies of the formats for the field registration and custody chain.
7. Two or three sampling and flow measuring campaigns, separating the period, are carried out
in the water body and its tributaries, as well as from its uses and specific contaminating
sources during the dry season. The analyses of the physical, chemical, microbiological
and toxicological parameters for the water samples are carried out.
8. The basic parameters that are always determined or analyzed are: pH, water and air
temperature, electric conductivity, dissolved oxygen, residual chlorine, turbidity, alkalinity,
DBO5, COD, cyanides, total solids, sedimentable solids, total suspended solids, total
dissolved solids, nitrogen in all its forms (ammonia, organic, nitrates, nitrites and total),
total phosphorous, organic phosphorous, dissolved phosphorous and orthophosphates, fats
and oils, hardness, floating matter, color, chlorides, sulfates, active substances to methylene
blue, total and fecal coli forms, arsenic, cadmium, copper, chromium, mercury, nickel, lead,
zinc, phenol and toxicity (Vibrio fisheri and Daphnia magna). The inorganic parameters,
volatile organic compounds and semi volatile compounds are included only when necessary,
according to the industry type that is discharging its wastewater to the water body.
9. The sampling of the specific contaminating sources is the compound type of 24 hours,
according to NOM-001-SEMARNAT-1996 for industrial discharges and simple type for
municipal discharges as well as for the water body and its tributaries.
flow measurement of each site is done simultaneously.
The sampling and
Also, the required environmental
parameters will be determined by a mathematical model (such as atmospheric pressure,
temperature measured by dry and humid bulb, etc.), as well as the hydraulic characteristics
of the water body (area of the section, water speed, flow, slope, ruggedness, etc.).
63
10. The sampling works and water quality analysis should be carried out by accredited
laboratories and personnel from the Mexican Accreditation Entity (EMA, Entidad Mexicana
de Acreditación) and approved by CONAGUA
11. The techniques and the quantification limits that are reported by the laboratories that carry
out the tests should allow the evaluation of the results regarding the strictest values
established in the current Ecological Water Quality Criteria (CE-CCA-001/89), in the case
of the water body, its tributaries and wastewater discharges.
Furthermore, the certainty
values, the detection and quantification limits, the work interval values and the quantifiable
minimum (for non instrumental methods) are also indicated in each report attaching the
pages with the results from the metal analysis equipment and the chromatograms from the
organic compound analysis equipment.
12. From the reports containing the water quality results, obtained in the field and laboratory, a
database is made in Excel format, which is used to evaluate the results starting from the
development of charts and graphs selecting the information that will be used for the
mathematical model, as well as to feed the mathematical model of water quality.
The
Excel database contains the following information: code and name of the site, date, time,
number of the sampling and flow measuring campaign, laboratory, sample origin (municipal,
industrial sector, water body, tributaries). The results are input in the database in units of
mg/L, and those with a different unit will have the one used by the laboratory and/or from
the reference pattern with which the evaluation is carried out
13. .The water quality historical information will be evaluated from determined statistical data,
such as: maximum, minimum, average, pondered average, standard error, standard deviation,
percentiles 10, 25, 75 and 90, confidence and mean limits. The evaluation is done for each
one of the water quality parameters, by monitoring station, by year and by rainy or dry
season.
14. The evaluation and analysis, both the historical as well as the one resulting from the study,
will be made for the water body and its tributaries, based on the Ecological Water Quality
Criteria (CE-CCA-001/89) according to the water use that the body and its tributaries are
classified for in the Federal Law of Rights in water issues and for the use that will be
planted as the goal in the declaration. Likewise, an evaluation is done using the water
quality indicators corresponding to the BOD5, COD, fecal coli forms and nutrients (nitrogen
and phosphorous), and others established by CONAGUA.
64
15. The evaluation of the water quality data from the municipal and industrial wastewater
discharges is done based on the NOM-001-SEMARNAT-1996 and the use with which the
receptor water body has been classified and the daily average that the norm establishes.
16. The historical hydrometric data from the water body, its tributaries and its uses, is used
from the determination of the following statistical data: monthly, seasonal and annual
averages. The 7 consecutive days are determined with the lowest average in precipitation
during the last 10 years. The ecological flow of the water body and its tributaries is
determined, from the methodology established in the corresponding draft Norm, elaborated
by CONAGUA.
17. For the wastewater treatment systems, a description is made of the treatment procedures and
sludge, their characteristics, daily production and final disposition. The chemical products
and dosages used in the treatment are also mentioned.
18. Once the water quality and flow data is obtained from the study, the following is determined
(maximum, minimum, average, standard and medium deviation). The average monthly
flow is determined from the registered information in the hydrometric stations
corresponding to the month when the flow measuring was carried out.
19. Once the contaminant load is determined by parameter, parameter groups were made by
discharge and its type (municipal, non-municipal that includes a breakdown of industrial by
sector and services) for each one of the areas that the water body and its tributaries were
divided into.
20. The growth rate is determined as well as the population increase, for five year periods, of
the most important towns, located in the basin of the water body and which have an
influence in its quality and its tributaries.
21. The volume increase of the municipal and non-municipal wastewater discharges is
estimated, based on the results of the population growth and development plans of the
industries that are discharging directly or indirectly into the water body and its tributaries.
22. A diagnosis of the water quality is made based on the analyses and evaluation of the
historical information and the one obtained in the study. The water quality diagnosis
65
includes: the water quality tendencies of the water body and its tributaries, in time and
space; water availability in function of the water uses and its actual quality; main
contamination sources of the water body and its tributaries; contaminant loads being
discharged by the different specific pollutant sources; the possible effect of the diffuse
contamination sources and the geology of the water body basin being studied.
23. A mathematical model of the quality of the water body and its tributaries is carried out.
The mathematical model process begins with the calibration of the mathematical model
with the data obtained in the study.
Among the scenarios to be modeled is the compliance
of the wastewater discharges to NOM-001-SEMARNAT-1996; different percentages of
pollutant removal; the discharges of waters residual, better quality conditions of the water
body and its tributaries, according to the CE-CCA, and the use for which it is classified in
the Federal Law of Rights regarding water; wastewater discharges into the water body and
its tributaries.
For rivers, the mathematical model used is QUAL2e, developed by the US
Environmental Protection Agency.
24. The modeling of the different scenarios is carried out from the results obtained from the
mathematical model and the use of an Excel page. The assimilation and dilution capacity
of pollutants in the receiving body is determined. This is made through an Excel page,
which also allows to determine the assimilation and dilution capacity of the water body for
each one of the areas in which it was divided; the maximum discharge limits of the analyzed
pollutants that can flow into the water body and its tributaries; the compliance terms of the
maximum limits; and the quality goals wanted for the water body and its tributaries.
Excel
page can also help to determine the dilution of conservative pollutants that the mathematical
model QUAL2e does not simulate.
25. With all the gathered and obtained information from the study, and from the evaluation and
analysis, a report is made, which will be the technical foundation for the declaration of
classification, and which will be available for consultation, to whom requests it, once it is
published in the Official Gazette.
26. The proposal of the draft Declaration of Classification of the water body and its tributaries
is made based on the results of the mathematical model and of the analysis of the water
quality parameters that were not modeled. The Declaration includes the following: legal
framework, considerations, boundaries of the classified areas, definitions, parameters that
will be complied in the discharges into the water body, assimilation and dilution capacity in
66
the water body by area, terms of compliance of the maximum limits, maximum discharge
limits of the analyzed pollutants that can be received in the water body and its tributaries,
the quality goals for the water body and complementary articles.
27. This draft declaration is presented to the corresponding Basin Council (Consejo de Cuenca),
to get their support for the new regulation. The Council is composed of representative
water users from different sectors such as agricultural, industrial, municipal and services.
28. A legal revision by CONAGUA and SEMARNAT is carried out.
A Manifestation of
Regulatory Impact (Manifestación de Impacto Regulatorio) is elaborated and sent to
SEMARNAT.
29. In compliance with the Federal Law of Administrative Procedures (Ley Federal del
Procedimiento Administrativo), the drafts from the legal general dispositions, elaborated by
the Federal Public Administration (Administración Pública Federal), are accepted by the
Federal Commission of Regulatory Improvement (Comisión Federal de Mejora
Regulatoria), for their revision and verdict together with the Manifestation of Regulatory
Impact, when its execution implies costs for particular citizens.
Later on, the Secretariat of
Economy through the Federal Commission of Regulatory Improvement (COFEMER),
authorizes its publication in the Official Gazette (Diario Oficial de la Federacion). Finally
it is published and it goes into effect.
Recently two Declarations have been published, the one for the Coatzacoalcos River in the state
of Veracruz and San Juan del Rio in the state of Queretaro.
Declarations that are currently
being made are the following: Atoyac River in Puebla; Alseseca River in Puebla; Zahuapan
River in Tlaxcala; Cazones River in Veracruz; Blanco River in Veracruz; Apatlaco River in
Morelos, Acapulco Bay in Guerrero; Zihuatanejo Bay in Guerrero and Turbio River in
Guanajuato.
67
Appendix 3
Example of Factsheet
Cadmium
1.
General description
Name/Synonym
Cadmium
CAS Number
7440-43-9
Formula
Cd
Identity
Cadmium is a metal with an oxidation state of +2. It is chemically similar to zinc
and occurs naturally with zinc and lead in sulfide ores.
Physicochemical
Physical state
Soft white solid
properties
Density
8.64 g/cm3
Melting point
320.9 °C
Boiling point
765 °C at 100 kPa
Solubility
Soluble in dilute nitric and concentrated sulfuric acids
Major use
Cadmium metal is used mainly as an anticorrosive, electroplated onto steel.
Cadmium sulfide and selenide are commonly used as pigments in plastics.
Cadmium compounds are used in electric batteries, electronic components and
nuclear reactors.
1)
RETC
Reported threshold from
Cadmium: 5
manufacturing, processing or use
Cadmium (compounds): 5
(kg/year)
Production &
consumption
2)
Environmental fate3)
Reported threshold from emission
Cadmium: 1
(kg/year)
Cadmium (compounds) : -
Production (ton): 1,755
(in 1995)
Export (ton) : 674,121
(in 1995)
Import (ton) : 3
(in 1995)
Fertilizers produced from phosphate ores constitute a major source of diffuse
cadmium pollution. The solubility of cadmium in water is influenced to a large
degree by its acidity; suspended or sediment-bound cadmium may dissolve when
there is an increase in acidity. In natural waters, cadmium is found mainly in
bottom sediments and suspended particles.
2.
Analytical Methods
68
Analytical methods3)
Cadmium can be determined by atomic absorption spectroscopy using either
direct aspiration into a flame or a furnace spectrometric technique. The detection
limit is 5 μg /L with the flame method, and 0.1 μg/L with the furnace procedure
Cadmium.
Limit of detection4)
3.
0.01μg /L by ICP/MS; 2μg/L by FAAS
Toxicological review
Kinetics, metabolism
Absorption of cadmium compounds is dependent on the solubility of the
and effects on
compounds. Cadmium accumulates primarily in the kidneys and has a long
humans
4)
biological half-life in humans of 10–35 years. There is evidence that cadmium is
carcinogenic by the inhalation route, and IARC has classified cadmium and
cadmium compounds in Group 2A.
However, there is no evidence of carcinogenicity by the oral route and no clear
evidence for the genotoxicity of cadmium. The kidney is the main target organ
for cadmium toxicity. The critical cadmium concentration in the renal cortex that
would produce a 10% prevalence of low-molecular-weight proteinuria in the
general population is about 200 mg/kg and would be reached after a daily dietary
intake of about 175mg per person for 50 years.
4.
Environmental levels and human exposure3)
Air
Cadmium is present in ambient air in the form of particles in which cadmium
oxide is probably an important constituent (Friberg et al., 1986). Annual average
concentrations in four cities in Germany in 1981–1982 were 1–3 ng/m3. In the
Netherlands, annual average concentrations in 1980–1983 were 0.7–2 ng/m3.
Levels are generally higher in the vicinity of metallurgical plants. In industrial
areas in Belgium, annual average levels in 1985–1986 were 10–60 ng/m3 (Ros &
Slooff, 1987). For the general population not living in such areas, cadmium
intakes from air are unlikely to exceed 0.8 μg/day (JECFA, 1989).
Cigarette smoking increases cadmium concentrations inside houses. The average
daily exposure from cigarette smoking (20 cigarettes a day) is 2–4 μg of
cadmium (Ros & Slooff, 1987).
Water
Cadmium concentrations in unpolluted natural waters are usually below 1 μg/L
(Friberg et al., 1986). Median concentrations of dissolved cadmium measured at
110 stations around the world were <1 μg/L, the maximum value recorded being
100μg//L in the Rio Rimao in Peru (WHO/UNEP, 1989). Average levels in the
Rhine and Danube in 1988 were 0.1 μg/L (range 0.02–0.3 μg/L) (ARW, 1988)
69
and 0.025 μg/L (AWBR, 1988), respectively. In the sediments near Rotterdam
harbor, levels in mud ranged from 1 to 10 mg/kg dry weight in 1985–1986, down
from 5–19 mg/kg dry weight in 1981 (Ros & Slooff, 1987).
Contamination of drinking-water may occur as a result of the presence of
cadmium as an impurity in the zinc of galvanized pipes or cadmium-containing
solders in fittings, water heaters, water coolers and taps. Drinking-water from
shallow wells of areas in Sweden where the soil had been acidified contained
concentrations of cadmium approaching 5 μg/L (Friberg et al., 1986). In Saudi
Arabia, mean concentrations of 1–26 μg/L were found in samples of potable
water, some of which were taken from private wells or cold corroded pipes
(Mustafa et al., 1988). Levels of cadmium could be higher in areas supplied with
soft water of low pH, as this would tend to be more corrosive in plumbing
systems containing cadmium. In the Netherlands, in a survey of 256
drinking-water plants in 1982, cadmium (0.1–0.2 μg/L) was detected in only 1%
of the drinking-water samples (Ros & Slooff, 1987).
Food
Food is the main source of cadmium intake for non-occupationally exposed
people. Crops grown in polluted soil or irrigated with polluted water may contain
increased concentrations, as may meat from animals grazing on contaminated
pastures (IARC, 1976). Animal kidneys and livers concentrate cadmium. Levels
in fruit, meat and vegetables are usually below 10 μg/kg, in liver 10–100 μg/kg
and in kidney 100–1000μg/kg. In cereals, levels are about 25 μg/kg wet weight.
In 1980–1988, average cadmium levels in fish were 20 μg/kg wet weight. High
levels were found in shellfish (200–1000 μg/kg) (Galal-Gorchev, 1991).
Based on cadmium levels measured in 1977–1984, the estimated daily intake in
food by the Netherlands population is 20 μg/person (IARC, 1976). The dietary
daily intake of cadmium has also been estimated to be in the range 10–35 μg
(Galal-Gorchev, 1991). In contaminated areas in Japan, daily intakes in 1980
were in the range 150– 250 μg, based on measurements of cadmium in feces
(Friberg et al., 1986).
Estimated total
Food is the main source of non-occupational exposure to cadmium, with dietary
exposure and relative
daily intakes, as stated above, in the range 10–35 μg. The intake from
contribution of
drinking-water is usually less than 2 μg/day (JECFA, 1989). Smoking will
drinking-water
increase the daily intake of cadmium. In western Europe, the USA and Australia,
the average daily oral intake of cadmium by non-smokers living in unpolluted
areas is 10–25 μg (WHO, 1992).
70
5.
Monitoring levels in water basins in Mexico
Period
Min (mg/L)
Max (mg/L)
Media
(mg/L)
5)
National Monitoring Network
2000-2007
-
-
-
Classification
Rio Apatlaco
1996
-
-
-
Rio Blanco
2003
-
-
-
Rio Cazones
2003
0.069
0.287
0.161
Rio Coatzacoalcos
2003
-
-
-
Rio Cotaxtla y Jamapa
2002-2003
0.0
0.005
0.005
Rio Panuco
2003
0.0005
0.050
0.004
San Juan del Rio
2003
<0.004
<0.004
<0.004
Rio Suchiate
?
-
-
-
Rio Turbio
2000-2007
-
-
-
Rio Turbio
2009
<0.005
<0.005
<0.005
Studies
6)
JICA Pilot Project
6.
7)
Criteria and guideline values
Mexican Norms
CECA (1989) 8)
NOM-001 (draft)
0.01mg/L
9)
0.01 mg/L
NOM-127 (draft) 10)
0.005 mg/L
International guideline values
WHO3)
0.003 mg/L
USEPA
(WQC)
-
A more stringent MCL has been issued.
11)
See below.
(Drinking Water Standards ) 12) 0.005 mg/L
0.00045 mg/L (maximum allowable concentration for Class 1: < 40 mgCaCO3/L)
0.00045 mg/L (maximum allowable concentration for Class 2: 40 to 50< mgCaCO3/L)
13)
EU
0.0006 mg/L (maximum allowable concentration for Class 3: 50 to 100< mgCaCO3/L)
0.0009 mg/L (maximum allowable concentration for Class 4: 100 to 200< mgCaCO3/L)
0.0015 mg/L (maximum allowable concentration for Class 5: ≥ 200 mgCaCO3/L)
14)
JAPAN
7.
7.1.
0.01 mg/L
MPC derivation and priority grouping in Mexico
MPC derivation
PTWI3)
Provisional Tolerable Weekly Intake (PTWI) is 7 mg/kg of body weight, on the
71
basis that if levels of cadmium in the renal cortex are not to exceed 50 mg/kg, total
intake of cadmium (assuming an absorption rate for dietary cadmium of 5% and a
daily excretion rate of 0.005% of body burden) should not exceed 1 mg/kg of body
weight per day.
Body weight (adult)
60 kg
Allocation to water
10% of PTWI
Daily drinking-water
consumption
2 L/day
MPC (draft)
0.003 mg/L
Quantification limit
0.005 mg/L @ National Reference Laboratory (CONAGUA)
USEPA (IRIS)15)
Critical Effect
Experimental Doses
Chronic Oral
Significant
NOAEL (water):
Exposure
proteinuria
0.005 mg/kg/day
Human studies
involving chronic
exposures
7.2.
NOAEL (food):
0.01 mg/kg/day
UF
MF
10
1
10
1
Reference Dose: RfD
0.0005 mg/kg/day
(water)
0.001 mg/kg/day
(food)
Priority group
Group 1
Priority Factor ( FP  CA MPC) > 1
• Average concentration of Classification Studies (CA): 0.015 mg/L
• Maximum permissible concentration (draft MPC): 0.003 mg/L
• 3 out of 4 rivers exceeded the draft MPC (see Section 5).
8.
References
1) SEMARNAT (2005), Diario Oficial de la Federación, ACUERDO por el que se determina el listado de
sustancias sujetas a reporte de competencia federal para el Registro de Emisiones y Transferencia de
Contaminantes, Primera Sección.
2) Instituto Nacional de Ecología (1995), Instituto Nacional de Estadística, Geografía e Informática.
http://www2.ine.gob.mx/publicaciones/gacetas/273/subtox.html
3) WHO (2008) Guidelines for Drinking-water Quality, THIRD EDITION INCORPORATING THE
FIRST AND SECOND ADDENDA, Volume 1, Recommendations, Geneva, World Health Organization.
72
4) WHO (2003) Cadmium in drinking-water. Background document for preparation of WHO Guidelines
for drinking-water quality. Geneva, World Health Organization (HO/SDE/WSH/03.04/80).
http://www.who.int/water_sanitation_health/gdwqrevision/en/index.html
5) CONAGUA (2008) Data from National Network for Measurement of Water Quality.
6) CONAGUA (2008) Data from Classification studies for 12 rivers (ALSESECA, APATLACO, ATOYAC,
BLANCO, CAZONES, COATZACOALCOS, COTAXTLA Y JAMAPA, PANUCO SAN JUAN, SUCHIATE,
ZAHUAPAN, TURBIO) and RIO TURBIO Pilot Project conducted by the Project on Capacity
Enhancement for Establishing Mexican Norms of Water Quality Criteria.
Three rivers, ALSESECA,
ATOYAC, ZAHUAPAN, recorded only the effluent data.
7) JICA (2009) Rio Turbio Pilot Project, Project on Capacity Enhancement for Establishing Mexican
Norms of Water Quality Criteria.
8) Mexico (1989) CE-CCA-001/89 Water Quality Ecological Criteria.
9) Mexico (2000?) Proposal for Modification of NOM-001-ECOL-1996 (Urban public use).
10) Mexico (2000) Modification of Mexican Official Standard NOM-127-SSA1-1994.
11) USEPA (2009) National Recommended Water Quality Criteria.
12) USEPA (2006) 2006 edition of the Drinking Water Standards and Health Advisories.
13) EU (2007) Proposal for Directive of the European Parliament and of the Council on Environmental
Quality Standards in the field of Water Policy and Amending Directive 2000/60/EC, Annex 1:
Environmental Quality Standards for Priority Substances and Certain Other Pollutants.
14) Japan (1993) Environmental Quality Standards for Water Pollution
(http://www.env.go.jp/en/standards/).
15) USEPA (1998) Integrated Risk Information System, Cadmium (CASRN 7440-43-9)
(http://www.epa.gov/ncea/iris/sbst/0141.htm/).
73
Appendix 4
Manual for Study of Chemical Analysis and Determination of Maximum
Permissible Concentration
Development of Analytical Method for Environmental Trace Analysis
For determination of Maximum Permissible Concentration (MPC) of environmental water
quality criteria, development/improvement/study of analytical method is important.
Development/improvement/study of analytical method is carried out considering following
process.
Ideal criteria value (ICV) is determined based on an environmental risk assessment for
human health or ecotoxicological test. Sometimes the value is determined without any
consideration about the level of analytical technique.
Limitation of existing instrument must be considered onto an ideal criteria value. This is
called Instrumental Quantification Limit (IQL) and equivalent to the limit of instrumental
sensitivity.
Analytical precision is sometimes lowered due to contamination or instability of recovery
on sample preparation procedure. Experimental Quantification Limit (EQL) includes
repeatability on sample preparation procedure.
Nowadays, EQL plays important rolls on trace analysis by high performance equipment
such as GC/MS than IQL.
Ideal criteria value
(Based on environmental risk for
(ICV)
human health, eco-toxicology test)
Limitation of existing instrument
Instrumental Quantification Limit: IQL
(Limit of instrumental sensitivity)
Limitation of
sample preparation
Experimental quantification
Limit: EQL
(Contamination,
unsteadiness of recovery)
MPC
74
Difference between IQL and EQL
IQL is calculated based on the instrumental repeatability on measurement of low
concentration standard-solutions, while EQL is calculated based on the experimental
repeatability on measurement of low concentration standard-solutions.
Ten (10) times the value of standard deviation from the results of repeated test is applied for
the both quantification limits.
For the calculation of standard deviation, seven (7) results for improvement of analytical
technique and five (5) results for routine work are usually used respectively.
Essentially the value of EQL is greater than that of IQL, because EQL includes repeatability
Instrumental QL
Residuals from
average value
measured value
measured value
of sample preparation as well as instrumental repeatability, which is the basic idea of IQL.
10σ
Experimental QL
Residuals increase
10σ
number of measurements
number of measurements
It is important to improve repeatability of sample preparation to lower EQL as low as IQL.
75
Improvement of Analytical Technique and determination of MPC
The following flowchart explains the procedure to determine MPC. Details are also
described below. Refer to the number in the flowchart for description.
1)
A>B
No
Value in literature (A)
1/10 of criteria value (B)
Yes
TQL=A
TQL=B
Target QL
(TQL)
2)
Determination of minimum
range of detection
Calibration Curve
Yes
3)
9)
Higher
-performance
equipment?
IQL test
9)
4)
No
Concentration/
dilution ratio
Improvement of
IQL test procedure
5)
IQL<TQL
No
Yes
6)
9)
No
Preliminary
experiment
Improvement
of technique?
9)
Yes
Improvement of test
procedure
No
Good
recovery?
>90% is ideal
7)
Yes
EQL test
No
8)
Tentative
MPC?
Yes
No
EQL<TQL
Yes
MPC=TQL
MPC
76
1)
Determination of Target Quantification Limit (TQL)
TQL is determined from either a value described by existing literature/manual (A) or 1/10
of criteria value (B):
If A>B then TQL=B
If A<B then TQL=A
2)
Calibration curve is obtained
Approximate minimum concentration range is determined.
3)
IQL test
Repeated measurement of standard solution at low concentration (7 times is
recommended) is carried out at lowest concentration obtained by procedure 2).
4)
Calculation of IQL
10 times of sample standard deviation is IQL
IQL should be converted to sample corresponding concentration by multiplying ratio of
concentration or dilution on sample preparation process to IQL.
5)
Comparison between TQL and IQL
If IQL>TQL then IQL test must be improved.
6)
Preliminary experiment
Preliminary experiment consists of following 3 parts.
a. Blank test
Measurement is carried out using distilled water. More than 2 samples are
recommended.
b. Recovery test with purified water
Standard solution added to distilled water is measured. 2 different concentrations are
recommended.
c. Recovery test with matrix sample
Recovery test using matrix samples is carried out. 2 different types of solution (addition
of standard solution and no addition) and 2 different concentrations are recommended.
The following items should be confirmed:
-
Existence of contamination in blank test
-
Difference of recovery rate between purified water and matrix sample
-
Linearity of response in 2 different concentration between purified water and
matrix sample
-
Existence of interference
-
Appropriateness of the concentration in the matrix samples (low concentration as
much as possible is recommended)
77
Over 90% of recovery rate is ideal, but 70% is sometimes acceptable.
If serious problem is found, improve the method and retry the preliminary experiment.
Trial-and-error test should be repeated to reach to the ideal recovery rate.
If necessary, reconsider and arrange the operation procedure.
7)
EQL test
EQL test consists of following 3 parts:
a. Blank test
Measurement is carried out using distilled water. More than 3 samples are
recommended.
b. EQL test
Matrix sample with standard solution (2-3 times of IQL) is measured. 7 parallel samples
are recommended.
c. Recovery test
Recovery test using matrix samples is carried out. 3 law matrix samples and 5 matrix
samples with standard solution (approximately 5 times of EQL) are carried out.
10 times of sample standard deviation of parallel measurement is EQL.
The following items should be confirmed:
-
EQL satisfies the target criteria value
If it does not satisfy the target value, blank water is high and varies or recovery
rate is low and varies.
-
Recovery rate is satisfied
Over 90% of recovery rate is ideal, but 70% is sometimes acceptable.
If the rate is not satisfied, something is wrong in sample preparation procedure.
8)
Determination of MPC
If EQL<TQL then MPC=TQL.
If not, identification of cause and establishment of countermeasure such as improvement
of procedure is necessary.
Replacement of higher performance equipment is another option.
Determination as tentative MPC using minimum value of EQL is also alternative.
9)
Improvement
Divide the process into several segments, and verify unsuccessful segment.
If recovery rate is low, verify the cause of failure.
In some case, the sample preparation process should be carried out with the standard
solutions to make a compensated (corrected) calibration curb.
If interference is serious, ingenious way such as additional clean-up process, another way
78
of measurement, change of measurement condition, exchange of chromatography column
or exchange to another type of instrument might be necessary.
Before trying such approaches, it is important to identify where the problem resides.
10) Consideration for the improvement of IQL
If available literature is used to determine TQL, the measuring conditions should be
improved.
Otherwise, the installation of higher performance equipment or the revision of TQL
should be considered.
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