Radon, a radioactive gas that seeps up from the soil and is the second-leading cause of lung cancer in the United States, is likely to exceed recommended limits in about 50,000 homes in Southern California, a yearlong study by The Times has concluded.
The 50,000 homes account for 1.2% of the households in the five-county region surveyed, strongly suggesting that Southern California is not confronted with nearly as extensive a radon problem as has been portrayed nationally.
Moreover, average radon levels in the region are one-sixth the recommended maximum established by the U.S. Environmental Protection Agency.
A total of 436 residences were tested in a Southern California region that includes Los Angeles and Orange counties and parts of Riverside, San Bernardino and Ventura counties.
The study found that the chances of exceeding the EPA’s recommended radon limit were higher than the Southern California average in an area that sweeps through fast-growing southeastern Ventura County and includes the Simi Valley, Thousand Oaks and Moorpark.
This discovery prompted a quick response from the state Department of Health Services, which assisted The Times in analyzing the data.
Department Director Kenneth W. Kizer ordered a comprehensive study of homes in much of Ventura County, including Oxnard, Ventura, Santa Paula, Simi Valley and the Santa Monica Mountains to pinpoint possible radon hot spots.
The state’s survey of 1,000 to 1,200 homes will also encompass the adjoining areas of Los Angeles County, including Agoura, Malibu, Beverly Hills, Westwood, Brentwood and much of the San Fernando Valley.
“In this general area where (radon levels) . . . have been found to be mildly elevated, we’re going to try to define what those boundaries are,” Kizer said.
The survey, which could begin within several weeks, will involve three times as many homes as the state is already monitoring for radon throughout California. The current survey is being conducted by the Department of Health Services and the state Air Resources Board.
The Times findings, which represent the largest radon study in California and the first in the state to systematically examine factors contributing to elevated levels, comes at a time of growing national concern over the health threat posed by the gas.
Three weeks ago, the EPA joined the Surgeon General’s office in issuing an unprecedented national health advisory urging virtually all homeowners in the country to test their residences for radon, a radioactive gas found in soils throughout the world.
But in the aftermath of the EPA advisory, a number of scientists, state officials and even the U.S. Department of Energy are questioning the EPA’s radon data and whether wide-scale testing by homeowners is justified.
Radon, which is produced by the natural decay of uranium, is the largest single source of human exposure to ionizing radiation in the environment. For most people, radon exposures far exceed the combined radiation from all other natural and man-made sources, including cosmic rays from space, medical X-rays, nuclear power plants and fallout from past atmospheric nuclear weapons tests.
Because of slight differences in air pressure inside the house and outdoors, the radon can be drawn into the house much like smoke is drawn up a fireplace chimney. The gas enters the house through cracks in concrete slab foundations, openings around plumbing and elsewhere.
The major threat to health occurs as the radon gas itself decays and throws off atoms of heavy metals called alpha particles or radon daughters.
The radon daughters attach to smoke and dust particles that are inhaled and lodge in the lungs, where they emit cell-damaging radiation.
The EPA estimates that radon may cause between 5,000 and 20,000 lung-cancer deaths each year and that nonsmokers may account for as many as 5,000 of those deaths. The National Academy of Sciences has placed the mortality figure at 13,000 annually. Smokers who are exposed to radon run 15 times the risk of lung cancer, according to radiation specialists.
The EPA estimates that between 8 million and 12 million U.S. households have radon levels exceeding its recommended limit of 4 picocuries per liter of air. The figure is based on short-term measurements of radon in 22,000 homes covering 17 states.
Exposure to 4 picocuries of radon for a year would be comparable to the risk of lung cancer from 200 to 300 chest X-rays a year or the risk to a nonsmoker of smoking a half a pack of cigarettes daily for a year, according to the EPA. The risk estimates are based on exposure at those levels for 75% of the time over a 70-year lifetime.
But based on an analysis of The Times’ data, not only are the EPA’s radon limits exceeded in only 1.2% of Southern California households overall, the vast majority of households are well below the 4-picocurie guideline. When radon levels in all households were averaged, the median radon level was slightly more than a half a picocurie per liter--0.6 pCi/l.
The Southern California findings are based on testing 436 residences of Times employees. The employees volunteered to place alpha-track radon detectors in their residences for a full year.
Because participants volunteered and were not randomly selected, the Los Angeles Times Poll conducted a random telephone survey of 462 individuals in Southern California to determine whether there were any differences between Times participants’ households and all other households.
Some differences in housing characteristics did exist between the Times employee sample and the overall population. But the data showed that housing characteristics did not significantly affect radon levels in the employee homes tested, according to Steven Hayward, manager of the state Department of Health Services’ Indoor Air Quality Program.
The primary factor in determining radon levels was the geographic location of the employee’s home, Hayward said. He observed that by making statistical adjustments, taking into account 1986 household data, it was possible to take the Times sample and fairly accurately project the percentage of homes in the study area that are likely to exceed 4 picocuries.
Based on such an analysis, Hayward said that there was a 95% probability that the number of households in the survey area exceeding 4 picocuries was between 20,000 and 120,000 and that the “best estimate” of the real number was 50,000.
“There’s a good deal of confidence that these numbers for the percentage of households greater than 4 picocuries per liter in each zone are reasonably representative of the general housing stock within that zone,” Hayward said.
Planning for the study was undertaken at a time when neither the federal nor state government had scheduled any testing of California homes.
Assisting in carrying out the study and analyzing its results was a scientific advisory panel that included Hayward, radiation physicists, a statistician, an environmental epidemiologist and a radiation geologist.
The Times’ findings contrast dramatically with the EPA’s disturbing view of the national picture.
Anthony V. Nero Jr., a physicist at the UC Lawrence Berkeley Laboratory’s Indoor Environment Program, said The Times’ study showed that the number of households in Southern California with a radon problem is “considerably lower than average.”
Not a ‘Substantial Concern’
“It’s a small enough fraction that it shouldn’t be a substantial concern for most citizens,” said Nero, a leading authority on radon.
Kizer, the state Health Services director, called The Times’ findings “especially good news. . . . It confirms, I think . . . that it is a very small proportion of homes in some areas where radon is higher.”
Kizer also stressed, as he did three weeks ago after the EPA advisory, that there is no justification for widespread testing of homes and apartments for radon.
In the meantime, he said, he would not discourage concerned homeowners from testing. But he said it was still too early for the state to recommend that everyone test.
He said there is no “imminent danger. There is time.”
That is not to say that there are not individual homes with relatively high levels, The Times’ survey showed. In southeastern Ventura County, based on a sample of 18 Times employees’ households, two were found to be over the EPA’s recommended maximum level. Because of the wide variation in radon levels from house to house and the small sample size, it is not possible to make inferences about radon levels for any single residence in this zone.
However, using standard statistical techniques that take such a small sample into account, it is possible to conclude that a greater percentage of homes in that vicinity are likely to exceed the 4-picocurie guideline, Hayward said.
One house in the Simi Valley had radon concentrations of 21.2 picocuries--the highest found in the study--and the level at which the EPA recommends that steps be taken “within months” to reduce radon levels.
Frank McConnell Jr., the owner of that house, said radon was the last problem he thought he would have. Then he got the results from the laboratory.
“I thought I lived on top of a uranium mine,’ said McConnell, who works in the Times’ mail room and transportation department.
McConnell said he placed the detector in a bathroom that was being remodeled. An exposed area in a wall, he said, could have provided a direct entry path for radon coming from the soil.
McConnell said he takes the radon reading seriously and is particularly concerned about the possible impact on the value of his house, where he and his wife and two daughters have lived for nearly five years.
“A major concern is if I ever want to sell the house. That’s by far my greatest concern now--disclosure,” he said. California law requires sellers to disclose to potential buyers anything they know that affects the habitability or marketability of the property. He said he will test additional rooms and take steps to reduce the amount of radon entering the house.
A house in eastern Orange County near Villa Park had the second-highest reading--9.6 picocuries, a level that the EPA says would increase a nonsmoker’s risk of lung cancer five times.
In descending order, the other three readings exceeding the EPA’s guideline were 5.1 picocuries in the Agoura Hills, 4.9 in Thousand Oaks and 4.3 in Northridge.
But these elevated readings were exceptions to generally low levels throughout the region and should not be used as a guide to predict radon levels in nearby homes. The only way of knowing what a particular house’s radon level will be is by testing it.
Even if two dwellings are identical, radon concentrations can vary because of differences in ventilation rates, the state of repair and even the kind of soil or geological formation beneath the house.
There are several possible explanations for the relatively higher readings in southeastern Ventura County, according to radiation geologist Barbara Moed of Geo-Radon Services of Berkeley. She noted that the surrounding mountains are rich in uranium-bearing granite. “It could be that region happens to have soils derived from granite in the San Gabriel Mountains,” said Moed, a consultant to the state Department of Health Services’ radon survey.
She said the San Gabriel and Santa Monica mountains also are rich in marine shale. Some marine shales, she said, also have higher uranium content. Other rocks with elevated uranium contents--andesite and rhyolite rocks--are also found in the area where higher radon levels were recorded.
As more and more information about radon is gathered throughout the country, longstanding argument within scientific circles has intensified over the risks posed by radon, and government’s response.
There is no doubt that radon causes lung cancer in humans. Studies of uranium miners in the United States, Canada and Europe have unequivocally established that fact.
“It does appear to be a real hazard,” said Naomi H. Harley, who headed a landmark study of occupational and environmental exposures to radon by the National Council on Radiation Protection and Measurement. “And unlike other things which we read about--for example, saccharin--whose studies are supported only by animal data . . . radon is different. We have data right at the levels that you and I live. I believe it’s hazardous, not hype,” she said.
The controversy comes when the question turns to how much radon it takes to cause lung cancer.
The EPA has calculated that even at its guideline level of 4 picocuries, three to 50 people out of 1,000 exposed for 70 years will die from lung cancer.
Nero said that risk estimate is exaggerated. “This (50 in 1,000) is a large risk, one that most scientists believe could only be associated with indoor concentrations of 10 to 15 picocuries per liter,” he said.
Some have called for doubling the EPA’s guideline to 8 picocuries. The standard in Canada is 20 picocuries.
So far, although some studies have indicated that lung cancer rates are higher in areas where radon contamination is greatest, the findings are not generally believed to be conclusive. There are several additional epidemiological studies by the National Cancer Institute and the U.S. Department of Energy under way in China, Sweden, New Jersey, Pennsylvania and Missouri, but the results are not expected for several years.
In the meantime, University of Pittsburgh physicist Bernard L. Cohen for the last several years has attempted to demonstrate that there may actually be fewer lung cancers in high radon areas. His suggestion is highly controversial.
In an interview, Cohen said he is attempting to determine whether there is a point when radiation is low enough that there is no adverse health effect. Cohen is thus questioning the widely held view that radiation is always harmful, even in small doses.
Tougher Stance Sought
Others, however, like Bob Yuhnke, regional counsel of the private Environmental Defense Fund, are calling for a much tougher stand by the EPA in warning of radon’s threat. Yuhnke has been especially critical of the EPA’s guideline of 4 picocuries.
“The EPA has led the public to believe that 4 picocuries is safe and nothing need be done about it when a house is below 4 picocuries,” Yuhnke said. “This is a really outrageous example of how the EPA has abandoned its mission to protect the public from a quite serious hazard. What we’re talking about here is the largest cause of lung cancer in the U.S. among people who do not smoke cigarettes.”
As a result of such concerns as those expressed by Yuhnke, legislation now before Congress would direct the EPA to make clear that radon is not safe even at levels as low as 4 picocuries.
Lately, the EPA has sought to clarify its 4 picocuries guideline, saying that it does not represent a safe level. Indeed, the EPA has said that exposure to radon at those levels for 70 years would be like having 200 to 300 chest X-rays a year or smoking half a pack of cigarettes a day.
But the EPA has said that 4 picocuries is probably the lowest achievable level in most homes that have high levels because of the limitations of technology and financial constraints.
Just how much a homeowner has to spend to reduce radon levels and whether marginal reductions are worth the cost is a factor in national policy debates.
“I think (the 4-picocuries guideline) is going to cause (the EPA) a lot of grief. Each survey turns up homes in need of action and so much money is going to be spent,” said Harley, chairman of the Institute of Environmental Medicine at New York University Medical Center.
She said that if there are 10 million homes in the country with radon levels above 4 picocuries and it costs an average of $1,000 to reduce radon contamination to 4 picocuries, the total bill to homeowners across the country would be $10 billion.
Criticism of EPA
The EPA is coming under increasing criticism for urging testing in virtually every U.S. household.
“I think it’s incredulous for 70 million households in the U.S. to do this,” Kizer said.
EPA Administrator Lee M. Thomas has defended the advisory. “We have a problem that is national in scope . . . and the problem is one that in some states is fairly widespread. The surveys bring us to the conclusion that we think it’s important for everyone to test their home,” he said.
But the validity of those very surveys has been called into question by some scientists, state officials and even the Department of Energy.
Susan L. Rose, the Department of Energy’s radon research program manager, said, “The DOE feels that for the vast majority of U.S. housing stock the question of radon risk is uncertain enough to warrant a major federal research commitment before widespread testing is urged for virtually every homeowner in the country.”
The EPA’s “methodology is suspect,” Nero said. “At every stage, the EPA tends to exaggerate the risk. I think the EPA is actively misrepresenting this issue with the American public,” said Nero, who has conducted numerous radon studies for the Department of Energy.
The EPA measured radon levels in homes only for a 48-hour period. In addition, the measurements were taken in the winter, when houses are closed up and radon levels are generally higher. Further, the EPA asked participants to place the radon detector in the lowest room in the house, such as a basement, where radon levels are higher.
Based on the results, the EPA said a third of the homes in the latest seven states it surveyed may have radon levels exceeding the recommended maximum of 4 picocuries.
But Nero disputes the figure. He said the EPA should have tested homes for a full year because radon concentrations vary from hour to hour and season to season. He also said the radon detectors should not have been placed in basements unless they were actually used as living quarters.
In response, the EPA argued that it intentionally chose to look for the highest possible readings in an initial screening test. The agency conceded that such screening measurements generally are two to three times higher than radon levels when averaged over a year.
But, the EPA argued, if a house could pass muster under worst-case conditions, chances were good that its radon problem the rest of the year would be minimal.
“I’m not telling them to abandon their homes or spend a lot of money,” said Richard Guimond, director of the EPA’s office of radiation programs. “We think it’s a good, prudent policy to let people know what the situation is.”
In the end, Harley said, how much radon exposure a person is willing to risk is a personal decision.
“It’s a judgment call,” she said. “It is my personal opinion that if a person wants to do something (to lower radon levels) and it’s a simple measure, it should be done, because radon is not good for people.”
EVALUATING RADON RISK Radon gas gives off radioactive alpha particles that can lodge in the human lung and cause tissue damage. The EPA and National Academy of Sciences have warned that radon is the nation’s second leading cause of lung cancer deaths. The National Academy of Sciences estimates that there are 13,000 lung cancer deaths a year caused by radon. The EPA’s estimate is between 5,000 and 20,000 deaths.
This guide shows how exposure to various radon levels over a lifetime compares to the risk of developing lung cancer from smoking and chest X-rays. The EPA recommends that action be taken to reduce radon levels in residences that test above 4 picocuries per liter of air.
Source: U.S. Environmental Protection Agency