Home radon risk is difficult to predict


August 31, 1993|By Dr. Genev | Dr. Genev,ieve Matanoski Contributing Writer

Recently, I've had a number of questions from women who have read about radon and wonder if they should be testing their homes for the level of indoor radon.

As it happens, I've done quite a bit of work on indoor radon exposure and will try to explain it.

As with so many human exposures, the answers are often complex, and it is difficult for women to know what they should actually do to protect themselves and their families.

Why is radon a concern?

Radon is a naturally occurring gas created as radium-226 decays. Radon escapes into the soil, water and air.

The problem in the home is that radon can escape from the soil and enter a basement through cracks in the walls.

When radon is breathed in and enters the lungs, it can damage the lining cells of the lung and contribute to lung cancer.

As with most cancer risks, the risk from exposure to radon depends on the amount of radon that gets into susceptible lung tissue.

What does this risk mean to me?

This is a difficult question, because most of the studies done on radon risks have been done on mine workers who work underground for years.

The exposure of these mine workers is calculated by estimating the level of radon and the number of hours they have worked in a month.

By this calculation, 100 "Worker Level Months" of exposure increase the risk of lung cancer in mine workers as much as three times over the general population. The risk for miners who also smoke is much higher.

Until recently, scientists thought that there were no serious exposures in homes, but discovered that home exposures could also pose a risk in some cases.

However, there are many differences between the risk of radon in mines and in homes.

There have been few studies on women and children who have residential exposure. The average level of radon in U.S. homes is 1.25 "picocuries" per liter (pCi/L) -- which, even with 70 years of exposure, would only equal about 20 "Worker Level Months."

Although most homes in the United States have very low levels of radon, a rare house may have levels that are much higher.

And, it is almost impossible to predict which houses will have these higher levels, although we do know that some areas are more likely to have high levels. We certainly need to do some good studies to understand radon risks in the home. Until then, we can only guess at the risks using the mining data.

Should my home be tested for radon?

All homes in which radon can seep in through the basement and rise to the first floor should be tested, and the Environmental Protection Agency is now recommending universal testing of homes. The test is inexpensive and easy. An alpha-track detector left in the lowest living area of the house for one year will give a good picture of average exposures.

If a faster test is needed -- as when a house is being sold -- a different instrument is placed in an unventilated basement for 14 days. The results of this kind of test are not as good a representation of average exposure as the yearlong one.

However, for now, most testing is done at the time homes are sold, rather than routinely by homeowners.

What should I do if the level is high?

The EPA currently recommends that if your home tests above 4 pCi/L, action should be taken to improve the situation (a level of 20 pCi/L is recommended for mines).

Corrective steps may be as simple as repair of cracks, but usually putting a cement slab in the basement and installing a ventilator pipe to remove radon gas is recommended.

Many newer homes are being built with protective devices in place. The cost of these steps is usually low and well worth the potential prevention of lung cancer.

Finally, I must add that to prevent lung cancer, the most important single thing a woman who is a smoker can do to protect herself and her family is to stop smoking.

For more information, the Environmental Protection Agency has a booklet, "The Homebuyers and Sellers Guide to Radon."

To request a copy, call (202) 233-9370.

Genevieve Matanoski is a physician and epidemiologist at the Johns Hopkins School of Hygiene and Public Health. She is a founding director of the school's Institute for Women's Health Research and Policy.

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