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Pesticide studies flawed
Lockwood warns higher allowable exposures could result
By LOIS BAKER
Contributing Editor
Studies using human subjects to determine a "no observable effect level" of pesticides do not meet widely accepted scientific and ethical standards for research and should not be used to set new standards, according to a scathing analysis published recently in the American Journal of Public Health.
A review of six studies obtained from the U.S. Environmental Protection Agency (EPA) under the Freedom of Information Act and conducted by Alan H. Lockwood, professor of neurology and nuclear medicine, found the studies flawed by conflict of interest, failure to meet ethical standards established by the Declaration of Helsinki, unacceptable informed consent procedures, inadequate statistical power and inappropriate test methods and end points.
All studies were funded by pesticide manufacturers and all ethics committees responsible for approving the study protocols were part of the contract research organizations paid by the company to conduct the studies, he found.
Lockwood cochairs the Environment and Health Committee of the national Physicians for Social Responsibility, but undertook this analysis on his own. The motivation behind these industry-sponsored human-dosing studies is clear, he said.
"The industries want to abolish, or at least reduce, the interspecies uncertainty factor and thereby convince the EPA to accept higher tolerances, which would benefit the industries financially," Lockwood added.
The interspecies uncertainty factor extrapolates the risk to humans, based on data from animal studies. It assumes that humans may be 10-fold more sensitive than the animal model and that children may be 100-fold more sensitive. If results of these human studies are accepted as adequate by the EPA, the concentration of pesticides in food might increase.
"To accept these studies would open the door to other poorly conducted studies and would violate the principal that those who engage in unethical activity should not reap rewards," Lockwood stated in his analysis. He also discussed pesticides on the National Public Radio program "Science Friday."
The analysis by Lockwood found several significant deviations from accepted ethical and scientific standards in the reports submitted to the EPA:
None of the study results appear in the scientific literature, indicating they were not conducted to advance generalizable scientific knowledge, the accepted criterion for scientific studies.
The studies' "failure to preserve the accuracy of results" violated the Declaration of Helsinki, which all studies claimed to use as their ethical standard.
None of the study protocols were reviewed by committees "independent of the investigator, the sponsor or any other kind of undue influence," as required by the Declaration of Helsinki.
Not all studies told participants why the study was being conducted or how the results would be used. Two identified the pesticide only as "the compound under test." One neglected to mention the most serious consequences, including death, of large amounts of the pesticide and implied that participants who withdrew for nonmedical reasons might not be paid, a condition amounting to coercion.
The studies lack full risk-benefit information; one study neglected to mention a report that found hospitalizations and stillbirths resulting from overexposure to its product.
All studies used too few participants, were too short to yield meaningful results and employed young healthy adults, who are least susceptible to pesticide effects.
None of the studies of these chemicals, which act on the central nervous system, used tests sensitive enough to detect small effects on brain function.
"Society has reaped enormous benefits from the use of pesticides," said Lockwood. "However, they are inherently toxic and great care is required as new standards are adopted, particularly those that govern childhood pesticide exposures. For this reason, these and similar pesticide-safety studies should be reviewed by scientific committees whose members are not influenced by politics or financial conflicts of interest."