Lung cancer kills thousands of Americans
every year. The untimely deaths of Peter Jennings and Dana
Reeve have raised public awareness about lung cancer, especially
among people who have never smoked. Smoking, radon, and secondhand
smoke are the leading causes of lung cancer. Although lung cancer can be treated, the survival
rate is one of the lowest for those with cancer. From the
time of diagnosis, between 11 and 15 percent of those afflicted
will live beyond five years, depending upon demographic factors. In
many cases lung cancer can be prevented; this is especially true
for radon.
Smoking is the leading
cause of lung cancer. Smoking
causes an estimated 160,000* deaths in the U.S. every year (American
Cancer Society, 2004). And the rate among women is rising. On
January 11, 1964, Dr. Luther L. Terry, then U.S. Surgeon General,
issued the first warning on the link between smoking and lung
cancer. Lung cancer now surpasses breast cancer as the
number one cause of death among women. A smoker who is
also exposed to radon has a much higher risk of lung cancer.
Radon is the number
one cause of lung cancer among non-smokers, according to EPA
estimates. Overall,
radon is the second leading cause of lung cancer. Radon
is responsible for about 21,000 lung cancer deaths every year. About
2,900 of these deaths occur among people who have never smoked. On
January 13, 2005, Dr. Richard H. Carmona, the U.S. Surgeon General,
issued a national health advisory on radon.
Secondhand smoke is
the third leading cause of lung cancer and responsible for
an estimated 3,000 lung cancer deaths every year. About 1,000 of these are people that
never smoked, and about 2,000 are former smokers. Smoking
affects non-smokers by exposing them to secondhand smoke. Exposure
to secondhand smoke can have serious consequences for children’s
health, including asthma attacks, affecting the respiratory tract
(bronchitis, pneumonia), and may cause ear infections.
Learning more about lung cancer.
The following
sources provide a wide range of good information about lung
cancer, prevention, and treatment.
(June 21, 2005) The
World Health Organization (WHO) says radon causes up to 15%
of lung cancers worldwide. In
an effort to reduce the rate of lung cancer around the world,
the World Health Organization (WHO) is launching a new international
radon project to help countries increase awareness, collect data
and encourage action to reduce radon-related risks. The U.S.
EPA is one of several countries supporting this initiative and
is encouraged by WHO’s attention to this important public
health issue. "Radon poses an easily reducible health risk
to populations all over the world, but has not up to now received
widespread attention," said Dr. Michael Repacholi, coordinator
of WHO’s Radiation and Environmental Health Unit. He went
on to say that "radon in our homes is the main source of exposure
to ionizing radiation, and accounts for 50% of the public’s
exposure to naturally-occurring sources of radiation in many
countries." Read the WHO Press Release Read the EPA News
Release
Why is radon the public health risk
that it is?
EPA estimates that
about 20,000 lung cancer deaths each year in the U.S. are radon-related. Exposure
to radon is the second leading cause of lung cancer after smoking. Radon
is an odorless, tasteless and invisible gas produced by the decay
of naturally occurring uranium in soil and water. Radon
is a form of ionizing radiation and a proven carcinogen. Lung
cancer is the only known effect on human health from exposure
to radon in air. Thus far, there is no evidence that children
are at greater risk of lung cancer than are adults.
Radon in air is ubiquitous.
Radon is found in outdoor air and in the indoor air of buildings
of all kinds. EPA
recommends homes be fixed if the radon level is 4 pCi/L (pico
Curies per Liter) or more. Because there is no known safe level
of exposure to radon, EPA also recommends that Americans consider
fixing their home for radon levels between 2 pCi/L and 4 pCi/L.
The average radon concentration in the indoor air of America’s
homes is about 1.3 pCi/L. It is upon this level that EPA based
its estimate of 20,000 radon-related lung cancers a year upon.
It is for this simple reason that EPA recommends that Americans
consider fixing their homes when the radon level is between 2
pCi/L and 4 pCi/L. The average concentration of radon in outdoor
air is .4 pCi/L or 1/10th of EPA’s 4 pCi/L action level.
For smokers the risk of lung cancer is significant
due to the synergistic effects of radon and smoking. For this
population about 62 people in a 1,000 will die of lung-cancer,
compared to 7.3 people in a 1,000 for never smokers. Put another
way, a person who never smoked (never smoker) who is exposed
to 1.3 pCi/L has a 2 in 1,000 chance of lung cancer; while a
smoker has a 20 in 1,000 chance of dying from lung cancer. Figure
A compares the risks between smokers and never smokers; smokers
are at a much higher risk than never smokers, e.g., at 8 pCi/L
the risk to smokers is six times the risk to never smokers.
The radon health risk
is underscored by the fact that in 1988 Congress added Title
III on Indoor Radon Abatement to the Toxic Substances Control
Act. It codified and funded EPA’s
then fledgling radon program. Also that year, the Office of the
U.S. Surgeon General issued a warning about radon urging Americans
to test their homes and to reduce the radon level when necessary
(U.S. Surgeon General).
Unfortunately, many
Americans presume that because the action level is 4 pCi/L,
a radon level of less than 4 pCi/L is ‘safe’.
This perception is altogether too common in the residential
real estate market. In managing any risk, we should be concerned
with the greatest risk. For most Americans, their greatest
exposure to radon is in their homes; especially in rooms that
are below grade (e.g., basements), rooms that are in contact
with the ground and those rooms immediately above them.
It's never too late
to reduce your risk of lung cancer. Don't wait to test and fix a radon problem. If
you are a smoker, stop smoking. Consider quitting. Until
you can quit, smoke outside and provide your family with a smoke-free
home (www.epa.gov/smokefree).
What
is Radon?
Radon is a gaseous
radioactive element having the symbol Rn, the atomic number
86, an atomic weight of 222, a melting point of -71ºC, a boiling point of -62ºC,
and (depending on the source, there are between 20 and 25 isotopes
of radon - 20 cited in the chemical summary, 25 listed in the
table of isotopes); it is an extremely toxic, colorless gas;
it can be condensed to a transparent liquid and to an opaque,
glowing solid; it is derived from the radioactive decay of radium
and is used in cancer treatment, as a tracer in leak detection,
and in radiography. (From the word radium, the substance from
which it is derived.) Sources: Condensed Chemical Dictionary,
and Handbook of Chemistry and Physics, 69th ed., CRC Press, Boca
Raton, FL, 1988.
EPA's Integrated Risk Information System profile
on Radon 222 [CASRN 14859-67-7] is located at: epa.gov/iris/subst/0275.htm
Sources of Radon
Earth and rock beneath home; well water; building
materials.
What are the Health Effects From Exposure
to Radon
No immediate symptoms. Based on an updated
Assessment of Risk for Radon in Homes, radon in indoor air is
estimated to cause about 21,000 lung cancer deaths each year
in the United States. Smokers are at higher risk of developing
Radon-induced lung cancer. Lung cancer is the only health effect
which has been definitively linked with radon exposure. Lung
cancer would usually occur years (5-25) after exposure. There
is no evidence that other respiratory diseases, such as asthma,
are caused by radon exposure and there is no evidence that children
are at any greater risk of radon induced lung cancer than adults.
What is the
Average Level of Radon Found in a Home?
Based on a national residential radon survey
completed in 1991, the average indoor radon level is about 1.3
picocuries per liter (pCi/L) in the United States. The average
outdoor level is about 0.4 pCi/L.
What's the Debate on Radon?
There is no debate
about radon being a lung carcinogen in humans. All major national
and international organizations that have examined the health
risks of radon agree that it is a lung carcinogen. The scientific
community continues to conduct research to refine our understanding
of the precise number of deaths attributable to radon. The
National Academy of Sciences BEIR VI Report has estimated that
radon causes about 15,000 to 22,000 lung cancer deaths annually
based on their two-preferred models. Major scientific
organizations continue to believe that approximately 12% of
lung cancers annually in the United States are attributable
to radon.
How do we know radon is a carcinogen?
The World Health Organization (WHO), the National
Academy of Sciences, the US Department of Health and Human Services,
as well as EPA, have classified radon as a known human carcinogen,
because of the wealth of biological and epidemiological evidence
and data showing the connection between exposure to radon and
lung cancer in humans.
There have been many studies conducted by
many different organizations in many nations around the world
to examine the relationship of radon exposure and human lung
cancer. The largest and most recent of these was an international
study, led by the National Cancer Institute (NCI), which examined
the data on 68,000 underground miners who were exposed to a wide
range of radon levels. The studies of miners are very useful
because the subjects are humans, not rats, as in many cancer
research studies. These miners are dying of lung cancer at 5
times the rate expected for the general population. Over many
years scientists around the world have conducted exhaustive research
to verify the cause-effect relationship between radon exposure
and the observed increased lung cancer deaths in these miners
and to eliminate other possible causes.
In addition, there is an overlap between radon
exposures received by miners who got lung cancer and the exposures
people would receive over their lifetime in a home at EPA's action
level of 4 pCi/L, i.e., the lung cancer risk in miners has been
documented at exposure levels comparable to those which occur
in homes/residences.
How many cases does it take to make
residential radon epidemiology studies meaningful?
To have a reasonable certainty in the conclusions,
many thousands of cases are required to detect the increased
risk of lung cancer due to radon. This is because the more things
that cause a disease the harder it is to separate one cause from
another, thus it takes many cases to pinpoint the risk from each
separate cause. The U.S. Public Health Service radon experts
estimate that 10,000 to 30,000 cases, and twice as many controls
would be needed to conduct a definitive epidemiologic study of
residential radon lung cancer risk. The residential studies conducted
to date have all included between 50 and 1500 cases and thus
have been too small to provide conclusive information.
Some years ago this same process was used
to detect an increased risk of lung cancer due to cigarette smoking.
It took many years of study to make the positive link between
the cause and effect of smoking and lung cancer. Most of the
increased lung cancer risk is attributable to smoking through
mathematical modeling. The research process for smoking was very
laborious. However, radon's process is even more challenging
because radon's contribution to increased lung cancer risk (12%)
is difficult to see against the large background of lung cancer
due to other causes, which include smoking, asbestos, some heavy
metals and other types of radiation; i.e., detecting radon-related
lung cancer is like trying to detect a 12% increase of sand on
a beach already full of sand.
Finally, it is difficult to accurately determine
radon exposures in residential settings since we are estimating
past exposures from current measurements. The number of required
study participants increases with the difficulty in determining
the exposure.
Why are residential epidemiology studies
of radon so complicated?
There are many factors that must be considered
when designing a residential radon epidemiology study. It is
very expensive and often impossible to design a study that takes
all the pertinent factors into consideration. These factors include:
Mobility: people move a lot over their lifetime; it is
virtually impossible to go back and test every home where
an individual has lived;
Housing Stock Changes: over time, older homes are often
destroyed or remodeled, thus radon measurements will be non-existent
or highly varied; a home's radon level may change, higher
or lower, over time if new ventilation systems are installed,
the occupancy patterns are substantially different, or the
home's foundation shifts or cracks appear.
Inaccurate Histories: often a majority of the lung cancer
cases (individuals) being studied are deceased or too sick
to be interviewed by researchers. This requires reliance
on second-hand information which may not be as accurate.
These inaccuracies primarily affect:
Residence History: a child or other relative may not be
aware of all residences occupied by the patient - particularly
if the occupancy is distant in time or of relatively short
duration. Even if the surrogate respondent is aware of a
residence they may not have enough additional information
to allow researchers to locate the home.
Smoking History: smoking history historically has reliability
problems. Individuals may under-estimate the amount they
smoke. Conversely, relatives or friends may over-estimate
smoking history.
Other: complicating factors other than variations
in smoking habits include an individual's: genetics, lifestyle,
exposure to other carcinogens, and home heating, venting and
air conditioning preferences.
Are there any residential epidemiology
studies finding increased risk of lung cancer due to radon?
Yes, several residential
epidemiology studies have found an increased risk of lung cancer
due to residential exposures (i.e. Sweden, New Jersey ) These
studies are also just pieces of a much bigger puzzle that is
being put together. The
National Academy of Sciences' BEIR VI Report examines in detail
the available studies of radon and lung cancer in homes, as well
as the studies of underground miners.
Why can we be sure about radon's health
risk?
We already have a wealth
of scientific data on the relationship between radon exposure
and the development of lung cancer. The scientific experts
agree that the occupational miner data is a very solid base
from which to estimate risk of lung cancer deaths annually.
While residential radon epidemiology studies will improve what
we know about radon, they will not supersede the occupational
data. Health authorities like
the Centers for Disease Control (CDC), the Surgeon General ,
the American Lung Association, the American Medical Association,
and others agree that we know enough now to recommend radon testing
and to encourage public action when levels are above 4 pCi/L.
The most comprehensive of these efforts has been the National
Academy of Science's Biological Effects of Ionizing Radiation
(BEIR VI) Report. This report reinforces that radon is
the second-leading cause of lung cancer and is a serious public
health problem. As in the case of cigarette smoking, it
would probably take many years and rigorous scientific research
to produce the composite data needed to make an even more definitive
conclusion.
What did the National Academy of Sciences
(NAS) published a report on radon and lung cancer say?
The NAS published its latest analysis of health
research on radon, the Biological Effects of Ionizing Radiation
(BEIR VI) Report in 1999. This is the most comprehensive review
effort to date. The Committee was charged with:
reviewing all current miner and residential data, as well
as all existing cellular-biological data,
comparing the dose per unit exposure effects of radon in
mines and homes, and examining:
interactions between radon exposure and smoking, and
any exposure-rate effect (alteration of effect by intensity
of exposure).
How can you find a qualified radon
service professional in your area?
If you are interested in finding a qualified
radon service professional to test or mitigate your home, or
you need to purchase a radon measurement device, you should:
Contact your State Radon Contact to determine what are,
or whether there are, requirements associated with providing
radon measurement and or radon mitigation's/reductions in
your State. Some States maintain lists of contractors available
in their state or they have proficiency programs or requirements
of their own.
Contact one or both of the two privately-run Radon Proficiency
Program (listed here alphabetically) who are offering proficiency
listing/accreditation/certification in radon testing and
mitigation.