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The Danger In Doomsaying Just how hazardous are dioxin, Alar and other chemicals? Skeptics call for a better method•of measuring risk M arilyn Leistner, doesn't believe sci- entists anymore-=at least not the, ones who once denounced dioxin but now downplay its dangers. Leistner was the last mayor of T'imes Beach, Mo.; the town of 2,400 that the U.S. government evactiatee3 and closed down in 1982 because it was contathinated with dioxin, considered by many to be one of the most fearsome of chemicals. The mayor saw dioxin's toxic effects all too clearly: the elderly forced out of their homes and into retirement centers, people so paran©id that every common illness was assumed to be dioxin poisoning, neighbors quarreling and even threatening to kill one another, "This chemical uprooted 801 families," she says. "The frustration, the divorces, the stress, the deaths can all be blamed on this chemical." Well, no. It was not so much the chem- ical that caused the chaos as it was a ques- tionable government judgment about the risks of diozin. Now that sdme scientists 7 are asserting-lU years too late-that the concentrations of dioxin present at Times Beach were not harmful, the dispossessed residents, and the public in general, have every right to be confused. There was a similar pattern of uncer• 1 tainty in judgments about Alar, radon and even some forms of Pcss and asbestos. Citing government studies, environmen- talists sounded the alarm about toxicity and cancer. The public fretted. Officials issued warnings and regulations. But then skeptical scientists re-evaluated the threat and began to argue that the risks had been exaggerated. After this series of debates, people are wondering if they have been unduly frightened by overzealous, if well- meaning, regulators. . At issue is risk assessment, the method of evaluating how dangerous a substance is to humans. In the U.S. officials have been quick to ban chemicals that accord- ing to lab tests are carcinogenic. But skep- tics contend the system is so sensitive that if standard tests were applied to all chemi- cals, both natural and synthetic, fully half of them would appear to cause cancer. "It's a bit like the search for witches. You can always find them," says Colin Berry, chairman of the British government's pes- ticide advisory board and a critic of the way American scientists have evaluated risk. Now that U.S. system of risk assess- ment is itself being reassessed. Just last a repair systems. Such a dose may also stim- ulate cells to divide rapidly, which magni- fies normal genetic errorsS and produces cancer. If traces of chemicals can cause can- cer, then the peril is inescapable. Most fruits and vegetables contain natural pes- ticides-chemical.c that plants themselves have manufactured to ward off bugs and blights--and about half these pompounds have tested positive as carcinogens. "Just because • something is natural . doesn't make it good, and just because sorttething is man-made doesn't make it bad," says Ronald Hart, director of the Alational! Center for Toxicological Rr,search. A recent survey of the causes of can- cer, published in Science, concluded that "the perception that environmental pollu- month, for example, the Environmental Protection Agency reversed an earlier de- cision and eased restrictions on the use of a class of pesticides known as ssncs, . Proving that a chemical causes cancer is difficult, since the disease may not strike until years after exposure. Unable to wait that long, scientists have tried to speed up the process by feeding huge amounts of suspect chemicals to laboratory animals such as mice.'I}+pically they are given what is known as the maximum tolerated dose, HAZARDOUS W~45~` E`E S1~' . utaxt~ ca~~aMIN,~~•t€~ • ST~Y IN YOUR CAR • MINIMIZE FRAVEIL • KEEP 1AftlltQOiYS GLQSED • SrqY oN p~cVEME~fT. _ DRIVE SLOWLY Lelstner wwn nsayor of Tkees Beach wrtg everyone had ta gei out cd tawn an amount just below the lethal level. In the case of the artificial sweetener saccha- rin, mice were given the equivalent of hundreds of cans of diet soda a day; simi- larly, a person would have had to eat thou- sands of apples a day to get the maximum tolerated dose of Alar, a fruit-ripening chemical used by growers until it was with- drawn from the market because of a can- cer scare. If as few as five mice out of 200 given these megadoses develop tumors over two years, the substance is usually la- beled a carcinogen. ' Such a conclusion is based on a host of conservative assumptions, among them that the effect on mice is generally the same as on humans and that it makes no difference whether the chemical is swal- lowed, inhaled or rubbed on the skin. An- other questionable premise is that there is no safe dose of a carcinogen. In fact, the body may have evolved methods of coping with small amounts of such chemicals. But when lab mice are given a megadose of a chemical, it could overwhelm their natural tion is a major cancer hazard is incorrect." While estimates vary, many experts agree that pesticides and other environmental contaminants are responsible for no more than 1% of cancers and 5,000 deaths a year. The potential cost of erroneous risk assessments is enormous: America's bill for complying with environmental regula- tions could top $100 billion this year. Congress is considering whether to loosen the Delaney clause, a 1958 law that bans any amount of any carcinogen from the food supply. In the 33 years since De- laney was written, science has developed an ability to identify substances at levels unimaginable to politicians who originally voted for the measure. Today one part per quintillion can be detected-the same as a tablespoon of liquid in all the Great Lakes combined. As scientists become more so- phisticated in detecting potential carcino- gens and analyzing test results, lawmakers and consumers will have to become more sophisticated in deciding how to balance the risks against the benefits.  TIME, MARCH 9,1992 61