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Ethics of human pesticide studies questioned

January 9, 2003




WASHINGTON (Reuters Health) - Scientists and environmental groups urged a federal advisory panel Wednesday to recommend a ban on chemical industry experiments that test the safety of pesticides and other potentially toxic chemicals in humans.

Labeling the experiments unethical and scientifically suspect, the groups asked experts on a National Academy of Sciences panel to condemn the studies and recommend that government regulators refuse to consider them when evaluating the safety of companies' chemical agents or pollutants.

But representatives of the pesticide industry defended the experiments, saying that they are ethically sound and essential to accurately determining safe exposure levels for members of the public.

Manufacturers of pesticides or other chemicals sometimes give adult volunteers a dose of the product in order to determine what levels humans can tolerate without getting sick. Determining a safe level for humans is necessary before companies can gain Environmental Protection Agency (EPA) approval to market most pesticides and other chemicals.

Scientists attacked the studies Wednesday, calling them unethical because people can only be hurt, and not helped, by receiving doses of toxic chemicals.

Most ethical standards for human medical research, including the Nuremburg Code created after the trials of Nazi doctors conducting research on World War II Holocaust prisoners, require that study participants stand a chance of gaining from research conducted on them.

"There is no benefit to the health of a subject nor to the health of anyone else," said Dr. Lynn Goldman, a professor of environmental health sciences at Johns Hopkins University and chair of the Children's Environmental Health Network.

Goldman conducted a study of a 1985 case in which up to 1,373 people were sickened after eating watermelon contaminated with the pesticide Aldicarb. Researchers uncovered probable illnesses in persons exposed to Aldicarb levels 10 times lower than those deemed safe in a 1971 study in which manufacturer Union Carbide gave it to 12 men.

The NAS panel is scheduled to meet over the next year to eventually advise the EPA on the propriety and scientific validity of human chemical tests. Citing ethical concerns, EPA in 2001 imposed a moratorium on accepting data from human chemical tests, a move that sparked a lawsuit by the pesticide industry.

Companies frequently test the effects of their chemicals in animals before applying for government marketing approval. When a chemical has not been tested in humans, the laws often require EPA to assume that a safe level for humans is many times--sometimes 100 times--lower than the level that causes sickness in animals.

Industry scientists told the panel that human chemical testing is always done with the informed consent of subjects and that the trials are key to determining exactly how humans react when exposed to dangerous compounds.

"The knowledge we gain from human volunteer studies is absolutely critical," said Dr. Monty Eberhart, director of product safety management for Bayer CropScience. The company is a major pesticide producer and one of the companies suing the EPA to lift the moratorium on human-derived data.

Eberhart told the panel that animal studies have often failed to accurately predict safe pesticide levels for humans.

"Only human data directly reflects human response," said Judith A. MacGregor, a researcher with Toxicology Consulting Services, a private research company.

But Goldman, of Johns Hopkins University, cited her study as proof that small trials testing chemicals in adult men tell little about how the compounds will effect people of different ages or sexes. One of the people hospitalized after eating the contaminated watermelon was a 66-year-old woman.

Others accused the industry of trying to use the self-financed experiments to weaken environmental standards governing its chemicals. Though many of the trials are conducted in only a few people, they could still be used to permit easier marketing if they showed that humans could tolerate a higher chemical dose than animals can.

"These tests are performed for the purposes of weakening regulatory standards," said Jennifer Sass, a senior scientist at the Natural Resources Defense Council.

Peg Cherny, vice president for government relations at Bayer CropScience, denied that the company's position or its lawsuit to force EPA to accept human studies is an attempt to weaken safety standards.

"We're trying to get appropriate standards," she said in an interview.

Lawyers for the EPA and pesticide industry are set to argue the case before the Federal Appeals Court in Washington in March.

The NAS panel is due to release its recommendations on human-based chemical testing in about one year, officials said.

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