Latest Pesticide Scare Dismissed by Scientists

Published February 1, 1998

Experts in nutrition and food safety have overwhelmingly rejected a report released January 29 by an activist environmental group alleging that over one million American infants and children are exposed each day to unsafe doses of pesticides in their food.

The report, “Overexposed: Organophosphate Insecticides in Children’s Food,” is the most recent in a long series of efforts by the Washington-based Environmental Working Group (EWG) to convince the public that minute amounts of pesticide residues pose a threat to the nation’s supply of food and water. Borrowing a tactic used with increasing success by EPA to justify many of its new regulatory initiatives, the EWG report highlights the alleged special vulnerability of children and infants.

The report alleges that some one million American infants and children age five and under are exposed to levels of organophosphate (OP) insecticides that exceed EPA safety standards, and that baby food represents the primary source of unsafe exposure for infants. EWG researchers focused on 13 OPs, recommending that home and structural use of the insecticides be banned; that at least five high-risk OPs be prohibited from all agricultural use; and that all OPs, residues of which are found in baby food, be banned.

Organophosphates have been used widely for over forty years to protect crops, notably corn and cotton, from termites, roaches, and other pests. Actually a family of several dozen insecticides, OPs share a common toxicological action, interfering with a nervous system enzyme known as cholinesterase, which is normally responsible for regulating activity in the nervous system.

As is true of chemicals generally, the risks from exposure to OPs depend on how much one is exposed to over what period of time. The EWG calculated exposure to individual OPs using EPA pesticide residue data and government food consumption estimates. The resulting exposure estimates were compared to EPA’s Reference Dose (RfD) for each of the pesticides. The RfD represents what the agency considers to be the maximum daily exposure to a pesticide that would not cause harm when ingested over a lifetime.

While the EWG report contends that infants and children are exposed to OP levels that exceed EPA safety standards, the agency in fact has no such standard. The OP standard referred to by the EWG is one of its own making.

Suspect Methodology

According to Dr. Karl K. Winter, director of the FoodSafe Program and associate extension food toxicologist for the Department of Food Science and Technology at the University of California-Davis, dietary pesticide risk assessments commonly require a series of assumptions to be made about 1) how toxic (potent) the pesticide is, 2) how much residue is on foods, and 3) how much and which types of food are commonly eaten.

With regard to the residue level assumption, EWG researchers combined results from the USDA Pesticide Data Program, FDA’s Total Diet Study, and FDA’s surveillance monitoring program. While the first two of these data sets represent relatively random monitoring programs that may reflect typical pesticide residue patterns, Dr. Winter points out that the FDA’s surveillance monitoring program “clearly represents a statistically unrepresentative and skewed sampling scheme designed to maximize FDA’s chances of detecting illegal pesticide residues, rather than providing a random sampling of residue levels and patterns.”

The EWG acknowledges that “the data do not provide a strictly statistically representative picture of pesticides in the US food supply.” It nevertheless stands by its use of those data, noting that “this shortcoming, however, is largely offset by the sheer size of the data base generated by the program and the fact that the program does sample food from all regions of the country.”

“This logic is hard to follow,” Dr. Winter observes. “The use of invalid data results in invalid conclusions, and the ‘sheer size of the data base’ clearly skews the findings of the report to indicate an exaggerated level of exposure.”

Political, Rather than Sound, Science

Like scores of EWG studies before it, “Overexposed” was not subjected to independent peer review by qualified third-party scientists or scientific organizations. The report seems designed not to contribute to an enlightened debate on public health issues, but to frighten parents and prod EPA into tightening pesticide standards.

“The theoretical risks posed by exposure to trace amounts of pesticides in the food supply pale in comparison to the health benefits of fruit and vegetable consumption,” Dr. Winter notes. “Parents should continue to do everything they can to make fruits and vegetables a major component of the diets of their children.”