Radon and Cancer - New Hampshire Comprehensive Cancer

Radon and Cancer - New Hampshire Comprehensive Cancer

EMERGING ISSUES BRIEF
Together-Eliminating Cancer
Radon gas can seep into a house through the basement and foundation.
Radon and Cancer
By Angeline S. Andrew PhD, Assistant Professor, Norris Cotton Cancer Center
Radon gas is the second leading
cause of lung cancer after tobacco
smoke worldwide.1 In the United
States approximately 18,600 lung
cancer deaths per year are attributed
to residential radon exposure, and
lung cancer risk is 29 percent higher
for people exposed to high levels of
radon gas in their homes compared
to those with low exposure.2
One in three NH homes may
have elevated levels of radon
The New Hampshire Department
of Environmental Services estimates
that one in three New Hampshire
homes has elevated levels of
radon.3 Based on the local geology,
soil characteristics, and radon
Potential for elevated
indoor radon
measurements, the Environmental
Protection Agency considers all
http://www.epa.gov/radon/
counties in New Hampshire to have
moderate to high potential for elevated indoor radon levels (see map).
Why is residential radon exposure harmful?
The main source of radon exposure is contaminated indoor air. As a
radioactive mineral called uranium-238 decays in the rocks and soil
underneath a house, a colorless, odorless gas—radon—is released as
a natural byproduct. This radon gas can seep into the house through
the basement and foundation and attach to dust particles in the
air. When inhaled, these particles generate radiation that damages
deoxyribonucleic acid (DNA) and other components of cells in the
lung.5 This damage can lead the lung cells to proliferate uncontrollably,
forming a tumor.
Studies of underground miners in the 1950s established the relationship
between radon and lung cancer, indicating that radon exposure
confers the greatest risk of lung cancer in the period 5 to 15 years after
exposure.4 But the prognosis of lung cancers associated with residential
radon exposure has not been extensively studied, and ongoing studies
have not identified molecular features unique to radon-related tumors
that can be used to guide cancer treatment.5
Radon exposure is associated with lung cancer among nonsmokers
and is estimated to cause 30 percent of the lung cancer deaths among
those nonsmokers who are not exposed to other lung carcinogens in
the workplace.6,7 Certain people may have inherited genetic factors that
make them particularly susceptible to radon-related lung cancers.8
Smokers are also more susceptible to radon gas-related lung cancer,
since the damage caused by tobacco smoke may synergize with the
effects of radon.9 Smoking in the home creates more particulates in the
air for radon to bind to, potentially increasing exposure and risk for all
inhabitants, including children. The radon-induced lung cancer risk is
25 times higher for smokers than for nonsmokers10 (smoking prevention
and cessation remain the most important way to avoid lung cancer).11
While radon gas can also be found in the water source supplying
a home, this is usually a minor source of risk compared to radon
exposure from soil. Small risks of stomach and gastrointestinal cancers
have been attributed to consumption of waterborne radon.10
How is radon in air or water measured?
The amount of radon in air or water is measured in Picocuries/Liter
(pCi/L). The Environmental Protection Agency has set 4 pCi/L as
the guideline level for airborne residential radon. During water use
small amounts of radon can be released into the air (10,000 pCi/L in
water contributes an estimated 1 piCi/L to air). The American Cancer
Society Cancer Prevention Study found a 34 percent increased risk of
death from lung cancer among participants exposed to mean radon
concentrations above this 4 pCi/L level.12 While 4 pCi/L is a threshold
used to identify those at the highest priority for exposure reduction,
levels below 4 pCi/L still pose a health risk10, and it is thought that
lung cancer risk actually increases incrementally with the amount of
radon exposure.2
Attempts have been made to predict which homes in the state are
likely have the highest radon levels based on the underlying geology.
A study conducted in 2006 revealed only modest correlations between
the soil types in New Hampshire and the actual observed shortterm residential radon levels. These data emphasize the importance
of measuring radon levels in each home, rather than relying on
predictions or assumptions.
A number of factors besides soil type can influence residential radon
levels, including home construction.13 Although granite can be a source
of radon, granite countertops are unlikely to cause high radon levels
in a home.14 Likewise, building materials are not usually a significant
source of radon.10 Use of radon resistant building practices should be
considered during new home construction.15 These practices include
installing a layer of gravel covered with plastic sheeting underneath
the home, sealing cracks in the foundation to prevent radon entry, and
running a vent pipe from the gravel layer through the roof to remove
any gas.15
How to test for residential radon exposure
Radon testing is recommended for all New Hampshire homes
(test kits are available through home improvement stores and the
National Radon Program Services).16 The U.S. Surgeon General and
the Environmental Protection Agency recommend that all residences
below the third floor level be tested for radon.17 Several different types
of tests measure the amount of radon in the air:
• A short term evaluation can be performed by placing a charcoal
canister test device in the lowest living area of the home, usually for
approximately one week.
• Long-term tests over a 3-12 month period provide a more accurate
estimate of exposure because levels fluctuate over time. Long-term
assessments should include the winter months, when the radon
may accumulate to higher levels because houses are sealed to
minimize heat loss.
Various remediation strategies can be used to reduce exposure in
existing homes with elevated radon levels. Sealing basements with
plastic sheeting and caulking cracks can help prevent radon gas
entry, however these measures are not usually sufficient long-term.
Installing pipes and exhaust fans can vent the radon gas from the
home (the average cost of installing such a system to reduce indoor air
radon levels is $1,200).16
To learn more about radon in New Hampshire go to: http://des.
nh.gov
NH Comprehensive Cancer Collaboration in partnership with Norris
Cotton Cancer Center at Dartmouth-Hitchcock
Together-Eliminating Cancer
August 2013
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