Toxic trespass

New analysis of pesticide drift indicates that hundreds of thousands of Californians are routinely exposed to concentrations of pesticides in excess of levels considered safe. These new findings challenge the inaction of regulatory authorities who are failing to protect public health.

California is one of the main agricultural areas of the US and applies more pesticide than any other state in the union. In 2000 alone 143 million kg of active ingredient were sold in California, over 90% of which were products prone to drifting.
    Pesticide drift is most noticeable when dusts or spray droplets are carried by air currents from the site of application. However, pesticides may also be carried on soil dust, and volatile pesticides may evaporate from the ground contaminating air for days, weeks, or months after the time of application.
    Air quality in California is monitored by both the Californian Department of Pesticide Registration (DPR) and the California Air Resources Board (ARB). In this new study monitoring data for six pesticides were analysed: for agricultural uses of the fumigants methyl bromide, metam sodium/methyl isothiocyanate (MITC), and 1,3-dichloropropene (Telone); the insecticides diazinon and chlorpyrifos; and the herbicide molinate. The levels detected were compared with Reference Exposure Levels (RELs) set by the United States Environmental Protection Agency for acute (short-term), sub-chronic (intermediate), and chronic (long-term) exposures. RELs are established for adults and children and are deemed unlikely to cause ill-effect.
    Near application sites (within nine to 154 metres), pesticide air concentrations exceeded acute RELs for MITC, chlorpyrifos, and diazinon for both adults and children, and molinate for children. Air concentrations in areas of high use (but not next to application sites) exceeded sub-chronic RELs for methyl bromide and MITC for adults and children; and chlorpyrifos, diazinon and molinate for children. Pesticide usage data indicated that chronic exposures to Telone projected from current use levels would substantially exceed the ‘acceptable’ cancer risk of one in a million.
    Pesticide drift is a much more significant cause of illness than generally recognised. Between 1997 and 2000 drift was responsible for half of all reported agricultural pesticide poisonings in California. Both methyl bromide and MITC/metam sodium present acute toxicity risks and several recent large-scale poisoning incidents caused by the latter have been recorded in California’s Central Valley.
    Chronic exposure to lower levels of pesticides have been associated with an array of conditions including birth defects, cancer, and sterility. Telone is associated with an increased risk of cancer. The insecticides chlorpyrifos and diazinon have been shown to reduce development of neural connections and are thought to be particularly hazardous to children. Molinate has been identified as a reproductive toxicant, neurotoxicant and possible carcinogen. (RM)

Kegley S, Katten A, Moses M, Secondhand Pesticides: Airborne Pesticide Drift in California , Californians for Pesticide Reform, 2003, www.panna.org/resources/documents/SecondhandPs.pdf

[This article first appeared in Pesticides News No. 60, June 2003, page 13]