Test Anxiety

Why are environmentalists afraid of pesticide research?

It's the Tuskegee syphilis experiment all over again! No, it's worse than that. It's the sort of research you'd expect from Josef Mengele!

Or so you might think based on a report that the Environmental Working Group (EWG) released at a July 27 press conference in Washington. The report documents the testing of various pesticides on human volunteers in England and Scotland beginning in the 1970s. The EWG, a tiny environmental group that nonetheless throws a long shadow, called for an immediate moratorium on such tests, demanding that the Environmental Protection Agency stop accepting them and stick to research with mice and rats. The Natural Resources Defense Council (NRDC), which also participated in the press conference, concurred.

The EWG's report presented no evidence that any of the volunteers in the pesticide studies had been harmed. Furthermore, anyone who understands the science behind this controversy will recognize that the EWG and the NRDC are not simply concerned about the welfare of human subjects. Environmental activists know animal testing is highly inexact, and they like it that way, the better to advance their agenda of hamstringing evil corporations and farmers at every turn.

Because rodents are quite different from humans, current regulatory policy requires the use of "safety factors" that greatly reduce the amount of pesticide that can be sprayed on crops but may not actually enhance safety. Under rules the EPA implemented from the agency's inception, you first determine the minimum amount of pesticide required to make an animal sick, then reduce that dose slightly. This is called the "no-effect level," or NOEL. To allow for the possibility that humans are more sensitive to the chemical than the test animals are, you divide NOEL by 10. Then you divide by 10 again to allow for especially sensitive humans.

The more you divide, of course, the less pesticide farmers can use to protect their crops. And if a given level is already safe, by definition it's impossible to make it safer by allowing even less. But that didn't stop environmentalists from crying, "Let's divide again!" They got their wish two years ago, when Congress passed the Food Quality Protection Act of 1996. The law authorized the EPA, at its discretion, to use yet another tenfold "safety factor"--dividing NOEL by 1,000 instead of 100--to protect children.

The new standard is so onerous that it will probably force farmers to replace many useful pesticides with products that are more costly and less effective. The rationale for the stricter standard is fuzzy, since children are already covered under the safety factor for "more sensitive" humans. Children also receive some coverage under the first safety factor, because animal testing often is done on infant or fetal rodents.

The environmentalists and the EPA know all this. So do the pesticide companies, which is what makes greater use of human testing so attractive to them: It could prove that the first tenfold safety factor, which assumes humans are much more sensitive than rodents, is needlessly strict. Such research obviously makes good economic sense for pesticide companies, farmers, food processors, and produce sellers. But it also makes good scientific sense, because human studies can tell us much more about safety than animal tests can.

Research with lab animals doesn't necessarily enable us to predict reactions in closely related species, let alone in humans. The furor over dioxin that continues to this day began when it was discovered that the tiniest amount knocked over guinea pigs like tenpins. But it took 5,000 times that dose to kill the same percentage of hamsters. Such experiences suggest that we should be careful about extrapolating from rodents to people.

I raised this issue at the EWG press conference. "Just as animals are better indicators than test tube experiments, aren't humans better indicators for human effects than animals?" I asked the group's vice president for research, Richard Wiles. "Absolutely," he conceded. This is precisely what disturbs the folks at the EWG. They've worked long and hard to get that third tenfold safety factor built into the law. If the pesticide companies manage to show that the first tenfold factor is unjustified, the environmentalists will be back at square one. Unable to attack the human testing on scientific grounds, the EWG tried to do so on ethical grounds. "Allowing human experiments, such as those conducted recently in the United Kingdom, to serve as the basis for registering pesticides, is ethically indefensible," EWG President Ken Cook said in a press release. But when questioned at the press conference, Wiles had to admit there was no evidence of unethical treatment. The testing was unquestionably legal under British and U.S. laws. A spokesman for Britain's Ministry of Agriculture, Fisheries, and Food said the tests "seemed to be along the right lines ethically." Medical ethics committees always review test protocols, and their decisions are reviewed every few years by international panels.

The EWG made it sound as if England and Scotland were chosen for the pesticide research because their citizens are easily exploited, like those poor Indians who sell their kidneys. Last time I checked, though, the United Kingdom did not qualify as a Third World country. A spokesman for one of the pesticide companies, Rhone-Poulenc Agro, said its studies were done in the U.K. because they "were commissioned by our parent company" in Lyon, France. In any event, some pesticide research with human subjects has been conducted in the United States.

Indeed, the EPA conducted its own human test to determine skin absorption rates of the medfly killer malathion in the early 1990s. In 1987, what was then called Ciba-Geigy (now part of Novartis) recruited six managers to swallow the herbicide atrazine. They were no more exploited than they were foreign.

The EWG report nevertheless provided fodder for the sensationalist wing of the British press. "Human Lab Rats in Secret Toxic Tests," cried a headline in The Birmingham Post. It's true that most of the tests weren't publicized, but why would they be? When was the last time a negative rodent study made the news? ("Our lead story tonight: Researchers in the United Kingdom have found that a widely used pesticide is harmless to mice. We take you now to our correspondent in London.") In any case, at least one of the human pesticide studies was publicized.

In 1992, Pesticide & Toxic Chemical News published an article about a study conducted in Scotland by Rhone-Poulenc. I know because I found it in the Nexis database. Not exactly a secret. Volunteers for these studies are recruited and paid by labs set up for such testing, not the chemical companies themselves. They are divided into test subjects, who swallow orange juice or corn syrup containing the pesticide, and control subjects, who swallow the liquid without the chemical. The amounts of pesticide involved are so tiny that any reactions are expected to show up only in blood testing, not in any observable symptoms.

In one Rhone-Poulenc study, the chemical was aldicarb, an insecticide in
the carbamate family. Carbamates work by inhibiting production of the enzyme cholinesterase, which is vital for nervous system functioning in humans as well
as insects. The EPA had proposed cutting the maximum permissible amount of aldicarb residues on food to one-fifth the existing standard, which would cause great hardship for farmers who need more to keep insects at bay. Rhone-Poulenc thought that if it showed no symptoms at levels much greater than any possible real-world exposure, it could get the EPA to reconsider.

So in 1992, a British lab administered aldicarb in orange juice to 36 people at four dose levels, while 22 controls had a pesticide-free drink. According to Rhone- Poulenc spokesman Richard Rountree, the doses were set well below the no-effect level established in animal research. Even when the pesticide could be detected in the subjects' blood, none of them displayed any symptoms of aldicarb poisoning, which include nausea, vomiting, diarrhea, blurred vision, muscular weakness, and difficult breathing. Rhone-Poulenc felt it had proven its point, but the EPA refused to budge on the stricter limit, noting that one of the test subjects had sweaty palms--which is not a symptom of aldicarb poisoning.

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