UC Davis Study Investigates Health Effects Of Paraquat, A Herbicide Commonly Used Throughout The World

Paraquat is one of the top three herbicides in use in the world. Valued for its effectiveness, rapid decomposition in soil, and lack of a toxic residue, it is commonly used in California. It is also heavily used in Latin America, where the tropical climate intensifies the need for a quick-acting herbicide. In Costa Rica, its use is unrestricted, and individuals can purchase paraquat for use in their own gardens. Its use in the United States is restricted to only certified applicators, and several countries, including Finland, Sweden and Austria, ban its use completely.

While case reports of accidental poisonings and suicide attempts have clearly defined the toxic effects of acute exposure to paraquat, the health effects of chronic low-level exposure is not well understood.

"At high doses and without immediate medical treatment, paraquat causes severe oxidative damage in the lung which is often fatal," said Marc Schenker, professor and chair of the Department of Epidemiology and Preventive Medicine. "We are investigating the long-term health effects of low-level pesticide exposure in Costa Rican farm workers to determine whether these workers are at increased risk for lung injury and related disease."

A leading authority on occupational and environmental diseases and respiratory illness, Schenker aims to recruit 500 workers from coffee, banana and palm oil farms throughout Costa Rica. Workers will be asked to complete an extensive work history questionnaire and undergo pulmonary function and exercise testing.

"This study is one of the largest and most intensive to be conducted in this population," said Schenker, a physician who is internationally regarded for his work on improving the working conditions of agricultural laborers. "We hope these studies provide a more definitive answer to the question about the safety of chronic low-level paraquat exposure."

The investigators plan to begin data collection in Costa Rica in May 2001 and hope to have preliminary results in 2002. Co-investigators of the paraquat study include exposure assessment specialist Kiyoung Lee and biostatistician Laurel Beckett, both from the Department of Epidemiology and Preventive Medicine, and toxicologist Bruce Hammock from College of Agriculture and Science's Department of Entomology. The two-year, $677,000 study is funded by Syngenta.

For more details about this study visit: http://wwwepm.ucdavis.edu/www/Projects/salud/Intro.htm