From October 24, 2001
Study Finds Pesticides
More Toxic to Fetus and Newborns
A recently published study in Environmental Health Perspectives finds that chlorpyrifos and other organophosphate pesticides can affect a fetus or newborn at concentrations that are nontoxic to adults. Dan Qiao, et al, of Duke University compared the effects of these pesticides and their major metabolites in two in vitro models, using neuronotypic and gliotypic cells.
The results indicate that chlorpyrifos and other organophosphates such as diazinon have immediate, direct effects on neural cell replication. Chlorpyrifos inhibited DNA synthesis in both cell lines but had a greater effect on gliotypic cells. The active metabolite that inhibits cholinesterase, chlorpyrifos oxon, also decreased DNA synthesis in both cell lines. Diazinon also inhibited DNA synthesis in gliotypic cells, but was less effective than chlorpyrifos. A non-organophosphate cholinesterase-inhibitor, physostigmine, was less effective than chlorpyrifos or diazinon, but the study found that it still caused significant inhibition of DNA synthesis of the gliotypic cells.
The authors state that the addition of sera protected the cells from the adverse effects of chlorpyrifos and that the effect could be reproduced by addition of albumin. The study goes on to discuss that in light of the protective affect of serum proteins, the fact that the fetus and newborn possess lower concentrations of these proteins suggest that greater neurotoxic effects may occur at blood levels of chlorpyrifos that are nontoxic to adults.
Under an agreement with the manufacturer, the EPA is requiring retailers to remove products containing chlorpyrifos, the most widely used household pesticide in the U.S., from store shelves by December 31, 2001. By this date, the pesticide may not be sold for use on school grounds or day care centers. EPA reached an agreement with manufacturers of diazinon, with a phase-out period that allows the pesticide to stay on store shelves into 2003. Environmentalists believe that both phase-outs are too long, and that EPA should have taken a stronger stance against the continued sale of the two pesticides. For more information on chlorpyrifos and diazinon, contact Beyond Pesticides.
Source: Qiao, Dan,
et al. "Developmental neurotoxicity of chlorpyrifos modeled in vitro:
Comparative effects of metabolites and other cholinesterase inhibitors
on DNA synthesis in PC12 and C6 cells. Environmental Health Perspectives
109(9):909-913.