Radon Causes Lung Cancer But How Do They Know That? By Michael Myers
Weíve all heard that indoor radon exposure causes lung cancer. In fact US EPA says that radon induced lung cancer kills about 21,000 Americans each year. And, that itís the leading cause of lung cancer in non-smokers. But how do they know that? How exactly do scientists determine the health hazards associated with any particular material?
There are basically four ways to establish a connection between a given material and a human health effect. They are:
A physical model that explains how the effect is delivered.
Animal studies showing a connection between the material in question and the effect.
Epidemiological studies showing the effects connection in humans.
A demonstrated opportunity for human exposure to the material in question.
In the case of radon, there is a very strong connection between exposure and an increased risk of contracting lung cancer. Letís explore this evidence as it relates to each of the above four items.
Physical Model for Damage Radon (222Rn) is chemically inert, but is highly radioactive with a half life of only 3.8 days. The short-lived radon decay products can be breathed in directly (unattached) or attached to particles of dust, lint or biological aerosols that are floating around in the air. Many of these decay products will be inhaled and adhere themselves to lung tissue. A portion of the alpha particles emitted will penetrate the lung tissue where cellular damage can occur.
The energy released by alpha particles can cause permanent damage to DNA molecules either physically or by chemical means. In most cases this damage causes the cell to die. Cells do however have the capability to repair themselves. There is a potential that damaged DNA will not be properly repaired and a mutation will occur. This mutation could be replicated in actively dividing cells, thus inducing lung cancer.
Animal Studies Animal studies provide useful health effect evidence. This is because they show impacts in mammalian tissues and organs that are similar in structure and function to those found in humans. The advantage of course is that theses studies can be conducted without exposing humans to potentially dangerous substances.
Hundreds of animal studies using dogs, rats and mice have shown a strong positive correlation between lung cancer and radon exposure. Human Epidemiology
Government recommended exposure levels for most known carcinogens are based solely on the first two kinds of evidence (physical model and animal studies). In the case of radon however, there are some human populations that can be studied to clearly assess the lung cancer connection.
The best epidemiological research has been occupational studies of various types of underground miners. The data collected from thousands of miners, carried out over 50 years worldwide has consistently and conclusively shown an increase in lung cancer risk with radon progeny exposure.
Residential case control studies have yielded similar findings. The Iowa Residential Radon Study, completed in May 2000, determined that even at the EPA Action Level of 4 pCi/l, an approximate 50% increase in lung cancer incidence was found. A 2002 Spanish residential study had similar results.
Demonstrated Opportunity for Human Exposure
US EPA has estimated that, on average, 15% of US homes have elevated radon levels. In addition high radon concentrations have been found in schools, work places and buildings of all kinds. The opportunity for human radon exposure is in every indoor environment.
Based on physical models, animal studies and human epidemiological studies; radon exposure has been positively linked to lung cancer. Health professionals agree that risk increases with higher concentrations and longer exposure times.
Putting This All Together
In conclusion, which ever way you look at the connection between radon and lung cancer there is a clear and present danger from radon exposure. The best way to protect yourself and your family is to radon test your indoor living environments.
HomeRadonTest.com provides a comprehensive web site to help families test their homes. Find out what type of radon test kits would be appropriate to your specific situation. If elevated radon levels are found, take immediate action to reduce exposure. Learn more about fixing a radon problem.