Pesticides Used Long Ago Resurface

The Main Contaminant, DBCP, Is Known to Cause Sterility and Is a Suspected Carcinogen

by Patricia McBroom

The first statewide evaluation of health risks from pesticides in drinking water has revealed a serious problem of contamination in some 50 towns and cities, mostly in the Central Valley and Riverside County, according to a Berkeley study.

The main contaminant, dibromo-chloropropane, is known to cause sterility in humans and is a suspected carcinogen.

Banned 15 years ago, DBCP was used for two decades as a subsurface weapon against root-eating worms. The pesticide filtered into ground water and now exceeds federal standards for safe exposure in about 1,700 wells throughout the state, affecting over 200,000 people, according to the analysis by an environmental health policy team at the School of Public Health.

"Pesticide contamination of drinking water poses a significant health risk in agricultural areas of the state," said William Pease, a toxicologist at the School of Public Health and lead author on the report. His co-authors were David Albright, Claire DeRoos, Laura Gottsman, Amy D. Kyle and Rachel Morello-Frosch.

The team worked under the direction of James Robinson, associate professor of public health.

In May, the city of Fresno won more than $100 million in an out-of-court settlement with the manufacturers of DBCP. At least half of the wells supplying that city's water are contaminated. Some $30 million has already been paid by the manufacturers to towns in affected areas, mostly along Highway 99.

The problem is primarily restricted to agricultural areas and does not affect most urban water systems, the analysis found.

But cities and towns in the Central Valley and several Southern California counties, as well as people using private wells in those areas, are "getting a cocktail of chemicals in their drinking water, and no one can say whether or not it is safe," said Pease.

He said that millions of pounds of DBCP were injected directly into the ground before the pesticide was banned in 1977 when campus health experts discovered that it made workers in a manufacturing plant in Lathrop, Calif., sterile.

The analysis, titled "Pesticide Contamination of Groundwater in California," was published by the California Policy Seminar.


Copyright 1995, The Regents of the University of California.
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