Parkinson's disease and exposure to agricultural work and pesticide chemicals

Karen M. Semchuk, PhD, Edgar J. Love, MD, PhD and Robert G. Lee, MD, FRCP(C)

Departments of Community Health Sciences (Drs. Semchuk and Love) and Clinical Neurosciences (Dr. Lee), Faculty of Medicine, The University of Calgary, Calgary, AB, Canada; and the Centre for Agricultural Medicine, Department of Medicine (Dr. Semchnk), College of Medicine and the College of Nursing (Dr. Semchuk), University of Saskatchewan, Saskatoon, SK, Canada.

This population-based case-control study of 130 Calgary residents with neurologist-confirmed idiopathic Parkinson's disease (PD) and 260 randomly selected age- and sex-matched community controls attempted to determine whether agricultural work or the occupational use of pesticide chemicals is associated with an increased risk for PD. We obtained by personal interviews lifetime occupational histories, including chemical exposure data, and analyzed the data using conditional logistic regression for matched sets. In the univariate analysis, a history of field crop farming, grain farming, herbicide use, or insecticide use resulted in a significantly increased crude estimate of the PD risk, and the data suggested a dose-response relation between the PD risk and the cumulative lifetime exposure to field crop farming and to grain farming. However, in the multivariate analysis, which controlled for potential confounding or interaction between the exposure variables, previous occupational herbicide use was consistently the only significant predictor of PD risk. These results support the hypothesis that the occupational use of herbicides is associated with an increased risk for PD.

Address correspondence and reprint requests to Dr. Karen M. Semchuk, Centre for Agricultural Medicine, University of Saskatchewan. Royal University Hospital, Saskatoon, SK S7N 0X0, Canada.

Supported in part by the National Health Research and Development Program, Health and Welfare Canada, through a grant (no. 6609–1473–53) and through a National Health PhD Fellowship to Dr. Semchuk.

Received July 11, 1991. Accepted for publication in final form December 5, 1991.