What is the evidence that indoor radon exposure is really a health risk?
The earliest evidence of radon-related health risk came from long-term cohort studies of underground miners conducted over the past 60 years. This evidence was of sufficient strength by 1988 that the World Health Organization’s International Agency for Research on Cancer (IARC) classified radon and its short-lived decay products as known human carcinogens (Group 1 or Class A). The National Cancer Institute has led the on-going study of 68,000 international underground miner radon risks. The National Academy of Sciences’ extensive assessment of the miner and other health risks associated with indoor radon is found in Health Risks of Exposure to Radon (BEIR VI) which is available HERE. Based upon this report, the U.S. Environmental Protection Agency (EPA) completed EPA Assessment of Risk of Radon in Homes which is available HERE. Since the 1980s, more than 40 residential case-control studies have been conducted. Overall, these studies reflected increased risk of lung cancer in homes with elevated indoor radon. In the mid-portion of the past decade, data from a number of residential case-control studies were pooled which allowed for more rigorous risk assessment (7 studies in North America; 13 studies in Europe; 2 studies in China). The risk estimates from the three sets of pooling studies virtually matched the risk estimates from the miner cohort studies; thus, giving very strong evidence that radon exposure in the home increases the risk of dying from lung cancer.
Further information about radon health risks is found in the World Health Organization’s WHO Handbook on Indoor Radon – A Public Health Perspective (a free copy is available HERE.
The strength of the evidence of the health risk associated with indoor radon exposure led WHO to recommend that (economically developed) countries establish radon reference levels, where mitigation would be recommended, at 100 Becquerels per cubic meter (Bq/m3) or 4 picoCuries per liter (pCi/L). The WHO recommendation is 33% or one-third lower than the EPA 4 pCi/L Threshold for Action. The Health Physics Society, an organization of 5,500 radiation safety professionals from 44 countries, recommends reducing exposures below 2.7 pCi/L www.eurekalert.org/pub_releases/2009-11/hps-hps112509.php and hps.org/documents/radon_position_statement.pdf (link gone)
I have heard that there is research that suggests that exposure to low levels of radon exposure do not pose a health risk. Is that true?
Yes, there have been “ecological” studies that suggest that there is not a risk of lung cancer at low levels of radon exposure. However, ecological studies should not be used for risk assessment. Some of those who argue hormesis (low doses of ionizing radiation are safe) are supported by those in the nuclear and chemical industry The National Academy of Sciences reviewed the health risk associated with exposure to low levels of ionizing radiation, including radon, and found, “The scientific research base shows that there is no threshold of exposure below which low levels of ionizing radiation can be demonstrated to be harmless or beneficial,” said committee chair Richard R. Monson, associate dean for professional education and professor of epidemiology, Harvard School of Public Health, Boston. “The health risks – particularly the development of solid cancers in organs – rise proportionally with exposure.”
Further information is available HERE. Other organizations that share the perspective of the National Academy of Sciences include: National Council on Radiation Protection Health Related Questions About Indoor Radon March 29, 2011 Board of Regents University of Minnesota Page 2 of 2 (UNSCEAR).
Do scientists and doctors agree about the lung cancer risk of radon exposure?
They do agree that radon exposure is a significant cause of lung cancer. There is some dispute with regard to the precise number of deaths due to radon induced lung cancer, but you would be hard pressed to find many individuals in the scientific community who think that radon is not a significant health problem.
The EPA recently revised their risk assessment to 21,000 radon induced lung cancer deaths. This is an increase of 150% over their 1994 estimate. The American Medical Association, the American Lung Association, the World Health Organization, the Center for Disease Control, and virtually all other health organizations agree that thousands of preventable lung cancer deaths occur every year.
Are children more susceptible than adults?
Yes. As children grow their entire body is developing and growing. They are more sensitive to radon exposure because their lungs are smaller and their respiratory rate is about twice as high. Many doctors believe that by the age of 10 a child has received twice the dose of an adult who has been exposed to the same amount of radon over the same period of time.
Does radon cause other types of cancer?
There is not definitive research that points to radon inducing other cancers. We do know, however, that surviving lung cancer patients are often stricken with other forms of cancer. While the other cancers cannot be attributed to radon, they are often a direct result of the previous cancer growth.
How do they know that it is radon causing these health problems?
Scientists use what they call biomarkers to identify and quantify exposure to radon. Biomarkers are indicators that signal specific events within individual biological systems.
Biomarkers of exposure to radon and its progeny (often referred to as “daughters”) include the presence of radon daughters in certain body tissues and fluids. Presence of radon and radon daughters are found in bone, teeth, hair, urine, blood, lung tissue, and even brain tissue. These biomarkers deposited in various systems of the body show that radon does, in fact, become absorbed by the body and impart gamma (and other) radiation as it further degrades.
Does radon cause health problems other than lung cancer?
A new study performed at the University of Nebraska has raised some new concerns in the minds of many researchers. While we know that radon increases the risk of lung cancer science has not, until recently, been linked to disease in other parts of the body. Dr. Berislav Momcilvic and Professor Glenn Lykken who led the study, assert that indoor radon gas has the destructive ability to infect the brain with radioactive heavy metal particles that may act as a basis for Alzheimer’s and Parkinson’s Disease.
What they found was that when radon gas is inhaled it can accumulate in lipid tissue throughout the body with the highest concentration in the brain, bone marrow, and the nervous system. It does not pass quickly out of the lungs when we exhale as once thought. Instead, it lingers harmfully in the body where some of it accumulates in the brain resulting in increased gamma ray emissions from Bismuth-214 (one of radon’s radioactive decay products (daughters)).
Scientists have recently noted the presence of radioactive (radon daughter) particles in the brains of non-smoking individuals afflicted with Alzheimer’s and Parkinson’s. Studies have shown that prevalence of radon was 10 times greater than it was in the brains of persons with no previous evidence of neurological disorders.
As further evidence that radon exposure may be a significant contributor to Alzheimer’s and Parkinson’s disease, according to D.J. Lansak of he University of Kentucky, the geographic distribution of Parkinson’s disease mortality is considerably higher in states with greater radon potential
I live in a newly constructed home. Is it true that I don’t have to worry about radon?
No. Not true. Radon intrusion can be a problem in all types of homes. new homes, old homes, drafty homes, well insulated homes, homes with basements, and homes on slab all can have hazardous levels of radon.
There are a number of factors that determine the level of radon in homes. The most significant is the geology of the area (the amount of uranium in the soil, porosity of the soil, etc.). But construction materials, how the home was built, and other factors certainly can contribute. We never know until we test for it what the level will actually be.
I am a smoker. I know I am not doing my lungs any good, but does radon make it worse?
Cigarette smoking is the most common cause of lung cancer. Radon represents a far smaller risk for this disease, but it is the second leading cause of lung cancer in the United States. You could say that it is the leading environmental cause of lung cancer. It is estimated that the number of radon induced lung cancer deaths in the U.S is approximately 21,000 people.
Exposure to a combination of radon gas and cigarette smoke creates a greater risk of lung cancer than exposure to either factor alone. The majority of radon cancer related deaths occur among smokers. However, it is estimated that more than 10% of radon related deaths occur among non-smokers. It is believed that most radon-related deaths among smokers would not have occurred if the victims had not smoked. In other words, the number of cancers induced in smokers by radon is greater than one would expect from the additive effects of smoking or radon alone.