UCLA Logo Some two years ago, UCLA scientists linked pesticide exposure to the development of Parkinson’s disease. And now a follow-up study suggests that people exposed to pesticides near workplace have higher chances of being diagnosed with Parkinson’s disease. It was detected that combined exposure to ziram, maneb and paraquat near any workplace increases risk of Parkinson’s disease by threefold.

Exposure to ziram and paraquat alone was supposedly associated with an 80 percent elevation in risk. Scientists also found that these pesticides affect different mechanisms leading to cell death. Pesticides affecting different cellular mechanisms that contribute to dopaminergic neuron death probably act together for elevating the risk of PD. A few years ago, investigators developed a geographic information system–based tool.

This tool presumably estimates human exposure to pesticides applied to agricultural crops, in accordance to the distance from fields on which pesticides are sprayed. This GIS tool apparently combines land-use maps and pesticide-use reporting data from the state of California. Each pesticide-use record may comprise the name of the pesticide’s active ingredient, the amount applied, the crop, the acreage of the field, the application method and the date of application.

“Our estimates of risk for ambient exposure in the workplaces were actually greater than for exposure at residences. And, of course, people who both live and work near these fields experience the greatest PD risk. These workplace results give us independent confirmation of our earlier work that focused only on residences, and of the damage these chemicals are doing,” quoted Dr. Beate Ritz, senior author and a professor of epidemiology at the UCLA School of Public Health.

From 1998 to 2007, a total of 362 Parkinson’s disease patients and 341 controls living in the Central Valley were inspected. Historical occupational and residential addresses were gathered from all the volunteers and a geographic information system model was put to use. Scientists then estimated ambient exposures to the pesticides ziram, maneb and paraquat, both at work and home, from 1974 to 1999. The critical window of exposure to toxicants possibly took place years before the onset of motor symptoms, when a diagnosis of Parkinson’s is made.

The research is published in the current online edition of the European Journal of Epidemiology.