Agricultural workers use pesticides to protect crops from insects, weeds, and other pests. However, these chemicals can cause serious health problems, especially if handled, applied, or disposed of improperly. Each year, physicians diagnose 10,000–20,000 pesticide poisonings among the estimated 2 million U.S. agricultural workers. When workers mix, load, apply, or dispose of pesticides, these harmful chemicals can enter the body through direct contact with skin, eyes, and clothes; eating or drinking pesticide-contaminated food or water; and breathing pesticide-containing mist, dust, fumes, or smoke. Exposure to some pesticides inhibits cholinesterase (ChE) – an enzyme necessary for communication between nerves and muscles. The brain and nerves are unable to control the movement of muscles. A low level of ChE can cause slowing of the heart, muscle paralysis, shivers, headache, convulsions, and coma. Pesticide poisoning is also associated with brain disorders such as Alzheimer’s disease.

The Western Center for Agricultural Health and Safety (WCAHS) at the University of California Davis – funded by the National Institute for Occupational Safety and Health (NIOSH) – conducted research focused on accurately measuring blood levels of ChE in agricultural workers. ChE test results are used to determine if a worker is properly protected from pesticides (e.g., trained on pesticide safety, used required personal protective equipment, applied pesticide according to the label). A worker’s test results are compared to his or her baseline level of ChE, which is measured when the worker is not regularly handling pesticides. WCAHS found that the accuracy of ChE test results depended on the commercial clinical test kit used. Unreliable test methods can make it difficult to compare changes in ChE levels and identify workers with pesticide poisoning. Under the leadership of Dr. Barry Wilson, a researcher from the University of California Davis, WCAHS developed a standardized method for measuring ChE to reliably test for pesticide poisoning.

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