The study, to be published Thursday, March 2, in the journal Pharmacogenetics and Genomics, reveals far greater variability in susceptibility to pesticides than previously predicted. Current U.S. Environmental Protection Agency (EPA) standards require an extra tenfold safety factor to protect children compared with adults if there are gaps in information about the children's susceptibility. The EPA may select a lower safety factor if it determines that enough information is available, and based on an EPA review, many other pesticides have lower or no additional safety factors.

But the new study "raises the question of whether current standards for safe levels of pesticide exposure are sufficiently protective of a vulnerable population," said Nina Holland, UC Berkeley adjunct professor of environmental health sciences and co-lead author of the paper. "Based on our study, I feel that more research is urgently needed to establish whether the standards need to be re-evaluated."

Since 2001, home use of organophosphate pesticides - diazinon and chlorpyrifos, in particular - has been restricted by the EPA, mainly because of risk to children. However, the researchers said there may still be residual exposure to diazinon and chlorpyrifos from household use before they were banned. Some structural uses for the pesticides are still approved, including treatment of house foundations with chlorpyrifos.

While household use of diazinon and chlorpyrifos is now restricted, these and other organophosphate pesticides are still widely used in agriculture. According to state figures, approximately 143,000 pounds of diazinon and 52,000 pounds of chlorpyr
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Contact: Liese Greensfelder
lieseg@berkeley.edu
510-643-7741
University of California - Berkeley
2-Mar-2006