KMAX: News of the West

Study: Rainfall contains high levels of pesticides

By KIM BACA
Associated Press Writer

FRESNO, Calif. (AP) Pesticides sprayed during the agricultural off-season have been found in high levels in rainfall in the San Joaquin Valley, threatening aquatic life, according to a U. S. Geological Survey study released Monday.

The levels of diazinon and chlorpyrifos collected in Modesto and surrounding fields during January and February rainstorms in 2001 exceeded levels safe for aquatic life, according to the study.

``It wasn't like you had pure rain and it picked up chemicals as it drained off. Sixty-eight percent of it had existed in the rainfall itself,'' said Charlie Kratzers, a U.S. Geological Survey hydrologist, who assisted in the study.

Glenn Brank, Department of Pesticide Regulation spokesman, said the levels of toxicity found in the samples were not a threat to human health but to tiny organisms such as water fleas.

The department, which sponsored the study, also is devising regulations to limit the use of these pesticides, he said.

``The winter rainstorm runoff as a primary source or component of transportation pesticides always seem to be a factor to us. What we have now is solid evidence and data on this,'' Brank said. ``This will support regulations we plan to implement later this year on pesticides on dormant sprays.''

Diazinon is a popular chemical used to kill insects in orchards from November to January to control hole-boring insects. Chlorpyrifos is a popular pesticide used in homes to treat termites and lawns.

Both chemicals, which can also runoff into streams, are organophosphates, a class of chemicals that are highly toxic. Excessive exposure can cause neurological problems.

Kratzers said the pesticides can get into rain after they are shot into the trees by a machine and they linger in the air sometimes for weeks or months before getting washed out or deposited.

Diazinon and chlorpyrifos already pollute the San Joaquin Valley's waterways. During the same study, researchers took samples from the San Joaquin, Merced, Stanislaus and Tuolumne rivers, and Orestimba Creek and found that 60 out of 240 of these samples exceeded state guidelines for safe levels. The highest concentrations of diazinon were found in the San Joaquin River, where concentrations exceeded the state guidelines.

Since 1996, diazinon manufacturers have been working on a plan to reduce runoff. The plan has showed some reduction, but not enough to meet safe levels for aquatic life, Brank said.

In December, diazinon will be phased out for residential use following a decision by the U.S. Environmental Protection Agency.

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On the Net:

The study: http://water.usgs.gov/pubs/wri/wri034091

Department of Pesticide Regulation: www.cdpr.ca.gov

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