Scientists take EPA's radon warning seriously. But they criticize home test methods and urge citizens to be patient

Scientists disagree on several important details of the assessment and study of radon in America, made earlier this week by the Environmental Protection Agency and the US Public Health Service. The disagreement revolves around the amount of radon that the EPA says is dangerous, the way the agency's latest tests in 17 states were conducted, and the two devices that the EPA recommends be used to test homes in the United States.

But the bottom line, Dr. Alan Ducatman says, is that ``there's no doubt'' that radon is a serious national health hazard. ``The gist of what they're saying is correct,'' he says.

It is a view with which many other scientists concur. Dr. Ducatman, medical and environmental director at the Massachusetts Institute of Technology, calls radon ``the No. 2 environmental'' hazard to the health of Americans, behind ``voluntarily inhaled'' tobacco smoke.

Ducatman says scientists have known for years that radon is hazardous to health but have been unable till now to arouse public interest ``because there is no villain. ... There's no government, ...there's no Russians, there's no big corporation, there's no illegal dumper doing it to them'': the earth is.

Radon is a naturally occurring phenomenon, a radioactive, colorless, odorless gas produced by the breakdown of uranium and radium found in rocks and earth. The gas can seep into houses and other buildings. The EPA estimates that 8 million US homes may be contaminated by radon levels that it considers too high. It urges homeowners to have their houses checked for radon. The EPA says excessive radon levels may be responsible for as many as 20,000 deaths annually in the US.

But there is no need to panic, scientists say. The potential for adverse effects is ``over years of exposure,'' says Bernard Cohen, a professor of Physics and Radiation at the University of Pittsburgh. Thus waiting a few weeks to begin the testing ``isn't going to make any difference.''

Dr. Cohen says a person's health risk because of radon increases the longer the exposure and the higher the radon concentration. But he, like some other scientists, says he feels the EPA's safety threshold of four picocuries of radon per liter of air is arbitrary. ``One man's opinion is as good as another,'' he says: ``I guess they felt that they had to choose a number and that's as good as any.''

Kent Jeffreys, an energy and environmental policy analyst at the Heritage Foundation, says this threshold is unnecessarily stringent. ``The problem with the EPA is that they knowingly overstate the case, because their edict is not to underestimate the risk. ... I have strong doubts that not enough study has been done on this issue.'' Mr. Jeffreys expresses concern that with its latest report the EPA ``unfortunately is going to panic an awful lot of people. And that's the real problem.''

For some scientists there's a problem with the way the EPA did its most recent screening measurements in 17 states. EPA's Stephen Page says they were done with charcoal-cannister devices that sampled the air for 48 hours. He says EPA considers these ``very accurate measurements for screening tests.'' (The EPA urges that homeowners whose tests produce high readings should undertake long-term tests with a different device, the alpha track detector, to learn whether high radon levels in fact exist.)

Cohen doubts that the EPA's screening methods are that accurate. He criticizes the EPA's use of open cans of charcoal. As ``radon levels in a room fluctuate ... what you're really measuring is what the radon level was shortly before you close up the can,'' because radon can escape the can as well as enter. He says more accurate devices exist, one of which he sells through his own private company.

Cohen agrees that the longer-term alpha track detectors have the ``big advantage'' of averaging radon levels over time, and thus can potentially provide a more accurate picture of whether a hazard exists in a building.

But Cohen says an alpha track detector test is only as good as the technician who interprets its results: ``You have to make judgments all the time.''

Two other problems exist with these tests, he warns. ``In side-by-side tests, the alpha tracks have done very poorly. They have typically a 25 percent deviation'' from one another, so that a homeowner's results could be off by 25 percent, potentially an important consideration if the radon level is considered borderline.

The second problem is public impatience. ``The public just doesn't seem to be willing to wait for a year'' to learn whether there's a problem with their houses, Cohen warns. ``People lose interest.'' The EPA agrees. That is why it recommends that homeowners first use the screening test, which takes only a week or so, to learn whether they may have a problem.

With even the experts disagreeing on details, it can be confusing for homeowners, unschooled in radiation, to know to whom to turn for honest and skilled testing. The EPA and state health agencies offer help here.

Within most state public health service offices is a radiation office, which can send homeowners a list of contractors whose test results the EPA has checked and found accurate; 243 contractors, some of them nationwide, are on the current list. In October the list will expand to 750.

These state offices also have other EPA-produced radon guides to help consumers protect themselves against those contractors who are not reliable. These list the seven most common ways to decrease radon levels, which vary according to the individual problem, along with estimates of what each might cost.