Study Criticisms Unjustified

Pesticides on Human Subjects Concluded “No Effect,” Despite the Evidence The National Academy of Sciences (NAS) convened a panel of scientists in early 2003 to advise the U.S. Environmental Protection Agency (EPA) on the scientific and ethical issues surrounding the use of toxicologic studies conducted by third parties on human subjects (NAS 2003). These studies are generally sponsored by chemical manufacturers to provide data for setting regulatory standards or for registering chemicals for commercial use. The test substance is frequently a pesticide or industrial chemical with no medicinal value. Studies of the pesticides dichlorvos (DDVP) and aldicarb are illustrative. The sponsors’ intent was to force the U.S. EPA to consider these data for setting exposure standards (Mitka 2003). DDVP, an organophosphate pesticide, exerts its toxicity through inhibition of acetyl cholinesterase. Symptoms of poisoning include diarrhea, vomiting, salivation, convulsions, and—in extreme cases— death. DDVP is widely used in pesticideimpregnated resin strips. It is listed as a possible human carcinogen by the International Agency for Research on Cancer (IARC 1991) and a probable human carcinogen by the U.S. EPA (1994). The AMVAC Chemical Corporation submitted a report to the U.S. EPA titled Dichlorvos: A Single Blind, Placebo Controlled, Randomized Study to Investigate the Effects of Multiple Oral Dosing on Erythrocyte Cholinesterase Inhibition in Healthy Male Volunteers (AMVAC 1997). According to the report, subjects were given 21 daily oral doses of 7 mg dichlorvos (six subjects), or placebo (three subjects). A venous blood sample was taken every 2–3 days, immediately before dosing. The authors (AMVAC 1997) reported that, compared with the group mean predose cholinesterase activity,