Shows Greater Human Vulnerability to Pesticides than Predicted
(Beyond Pesticides, March 7, 2006) A new study by researchers at University of California and University of Washington show much broader variability in sensitivity to organophosphate exposure than previously predicted.
The cohort study tracking 130 Pregnant Latino women and their newborns in Salinas County, California showes that newborns can be 65-164 times more sensitive than adults to two commonly used agricultural pesticides, chlorpyrifos and diazinon. One factor contributing to the increased sensitivity is a 26-fold variability among newborns in the levels of a key organophosphate detoxifying enzyme, PON1. It can take babies six months to two years to develop mature levels of this protective enzyme. Among the mothers, the variability of the detoxifying agent was 14-fold. EPA allows a safety margin of 10-fold to protect children.
The findings, published in Pharmacogenetics and Genomics, indicate that those individuals with less of the detoxifying agent are more suceptible to the adverse effects of specific organophosphate pesticides, such as impacts to the central nervous system and neurodevelopment.
While residential use of chlorpyrifos and diazinon has been restricted, agricultural use is still widespread and non-residential applications such as golf courses and road medians are still allowed. Science Daily reported that 143,000 pounds of diazinon and 52,000 pounds of chlorpyrifos are used annually in the Salinis Valley agricultural community on crops. Diazinon is used on lettuce, peaches, almonds, prunes and spinach while chlorpyrifos is used on cotton, alfalfa, almonds and walnuts in California.
As far back as 1993 the National Academy of Sciences (NAS) warned, “Little is known about children's sensitivity to pesticides. But data on other toxic chemicals suggest that children may be more sensitive than adults to some pesticides, while being less or equally sensitive to others.” NAS thought the variability in sensitivity was ”fairly small -usually less than tenfold,” and called for EPA to correct major deficiencies in its regulatory mechanisms to protect children. (see Pesticides in the Diets of Infants and Children (1993))
The Natural Resources Defense Council (NRDC) and the Northwest Coalition for Alternatives to Pesticides filed a lawsuit last August accusing EPA of failing to protect children's health as required by law, and as demonstrated by science. The NRDC reports that the litigation follows EPA decisions establishing new tolerances for several pesticides in dozens of different foods, including fruits, vegetables, milk, eggs, meat, cereal grains and vegetable oils. In each case, the agency had failed to apply a child-protection factor as required by the 1996 Food Quality Protection Act. The case is being heard by the 9th U.S. Circuit Court of Appeals in San Francisco.(see http://www.nrdc.org/media/pressreleases/030915a.asp)
Not only does this raise important concerns about the validity of EPA safety factors for children when they are applied, but with the announcement from the U.S. Geologic Survey just last week about the widespread contamination of our ground and surface waters with low level pesticides and degradates, standards used to set safe contamination levels for drinking water standards should be called into question. (Widespread Pesticide Poisoning of Water Focus of Landmark Government Study (Beyond Pesticides, March 3, 2006)
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Low-Dose Exposures to Pesticides May Threaten Developing Embryos