Pesticide Testing on Humans Is Ethical, Science Panel Says

By Shankar Vedantam
Washington Post Staff Writer
Friday, February 20, 2004; Page A03

It is ethical to test pesticides and pollutants on human volunteers in order to determine whether environmental safety standards can be lowered, a top panel of scientists said yesterday in an opinion that is expected to strongly influence government policy.

Many scientists and ethicists have argued that such research is never justified, and yesterday's unprecedented verdict by the National Academy of Sciences took environmentalists by surprise.

The pesticide industry has vehemently supported such tests for years, arguing that current regulatory limits on exposure to environmental toxins are overly cautious. Manufacturers of pesticides and companies that produce pollutants say human studies will demonstrate that higher levels of toxins in the air and water are not harmful.

While volunteers would derive no benefit and some might incur transient harm, the panel of experts said this would be outweighed by societal benefits. Besides helping regulators set accurate benchmarks for environmental dangers, such trials might also address, for example, how much insecticide can safely be used to fight a malaria outbreak.

Yesterday's decision by a panel of the National Research Council will allow the Environmental Protection Agency to devise a final rule over the next several months, an EPA spokesman said. Both the pesticide industry and environmental groups said they expect the agency will accept the recommendation of the panel, which would also allow the EPA to evaluate human studies of pesticides that had previously been conducted, and give the industry an incentive to conduct new trials.

The panelists called for a rigorous safety and ethics system to evaluate and approve such trials, much like the system used by the Food and Drug Administration to evaluate drug trials conducted by the pharmaceutical industry.

While there was no "foolproof mechanism" to eliminate all risk of patient harm, the joint chairman of the panel, James Childress, an ethics professor at the University of Virginia, said that the risk for volunteers would generally be "exceedingly low."

Environmental groups acknowledged that the panel had tried to institute safeguards, but feared that trials would still cause harm.

Currently, to determine what level of a toxin is safe for human exposure, regulators at the EPA first determine what dose is toxic to animals. Regulators divide that dose by 10, because humans may react more sensitively than animals -- called the "inter-species safety factor." Because some people are more sensitive than others, regulators lower the potentially toxic dose by another factor of 10. Finally, to protect children and fetuses, a third safety factor of as much as 10 is introduced. Collectively, these safety factors can reduce human exposure limits to toxins to one-thousandth the dose that harms animals.

The goal of human pesticide studies is to lower the inter-species factor. If companies can show that humans are not more sensitive than rats, higher exposure levels might be permitted.

Richard Wiles, senior vice president at the Environmental Working Group, an advocacy organization, said that while the EPA can enforce a tenfold safety factor to protect children, it does not do so for many chemicals. As a result, he said, the exposure limit for humans might end up being only one-tenth the toxic animal dose.

"Pesticide law would have gone from the toughest law on the books to the weakest law on the books through this marvelous sleight of hand that the industry has pulled," Wiles said.

The report allowed for the possibility of trials involving children, but panelists said they could not imagine such tests would ever be conducted. But Erik Olson, senior attorney at the Natural Resources Defense Council, an environmental group, said such tests have already been performed: As recently as 2000, he said, a manufacturer petitioned the EPA to consider data from an Italian study of infants that deliberately exposed them to dichlorvos, an insecticide sold under the brand name Vapona.

Dichlorvos manufacturer Amvac Chemical Corp., of Newport Beach, Calif., petitioned the agency to consider two 1969 trials titled "Exposure of Newborn Babies to Vapona Insecticide" and "Clinical Effects of Exposure to DDVP (Vapona) Insecticide in Hospital Wards."

A call to Amvac was returned by consultant Howard Berman, president of Environmental Mediation Inc. Berman said that the trials cited in the petition had not been commissioned by Amvac. Speaking on behalf of the company, he said Amvac had no plans to conduct trials among children.

Jay Vroom, president of Croplife America, which represents pesticide manufacturers, said he knew of no company that planned to test pesticides on children.

But data from adult trials would be useless in predicting the risk for children, said Philip Landrigan, a Mount Sinai pediatrician in New York and chairman of a National Academy of Sciences panel in 1993 that examined the risk of pesticides on children.

During the Clinton administration, the EPA refused to consider any human trials. The Bush administration reopened the possibility of using the tests.

The pesticide industry dismissed critics of the trials as biased, and environmental groups countered yesterday with similar criticism of the NRC panel. Olson, the NRDC attorney, produced documentation that panel member James Bruckner, a professor of pharmacology and toxicology at the University of Georgia, was a paid expert witness for Lockheed Martin Corp., which is fighting a lawsuit in California over whether pollution from its products might have caused cancer and thyroid problems.

Gail Rymer, a spokeswoman for Lockheed Martin in Bethesda, confirmed that the company had paid for a human study of a rocket fuel component called perchlorate in hopes of influencing the California lawsuit.

Bruckner and the National Academy of Sciences said there was no conflict of interest because he testified as an expert on a chemical called trichloroethylene and did not know about the perchlorate study.

Olson and Gary Praglin, who is suing Lockheed Martin on behalf of alleged victims in Redlands, Calif., said the argument was specious.

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