Pesticide exposure and risk of Parkinson’s disease – a population-based case-control study evaluating the potential for recall bias

This study assessed whether pesticide exposure was associated with Parkinson’s disease in a population-based, case control study in British Columbia, Canada. Patients reimbursed for anti-parkinsonian agents were identified and screened for eligibility as cases. Controls were selected from a universal health insurance database, frequency-matched to the case sample by birth year, gender, and geographical region. A total of 403 cases and 405 controls were interviewed concerning their job, medical and personal habits histories, and beliefs about disease risk factors. Among those reporting pesticide exposure, an occupational hygiene review selected participants exposed beyond background, i.e., above the level expected in the general population. Unconditional logistic regression estimated associations for different pesticide categories. Of the cases, 74 (18%) self-reported pesticide exposure; 37 (9%) were judged to be exposed beyond background. Self-reported exposure was associated with increased risk (odds ratio [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][OR] 1.76; 95% confidence interval [CI], 1.15-2.70); however, estimated risk was reduced following the hygiene review when restricted to those considered exposed (OR 1.51; 95% CI, 0.85-2.69). When agricultural work was added to the model, the risk for hygiene reviewed pesticide exposure was not elevated (OR 0.83; 95% CI, 0.43-1.61), but agricultural work was (OR 2.47; 95% CI, 1.18-5.15). More than twice as many cases as controls thought chemicals cause Parkinson’s disease. The authors concluded that based on the findings from the present study, there is little support for pesticide exposure as a cause of Parkinson’s disease. The observed pattern of step-wise decreases in risk estimates might indicate differential recall by case status. The relationship to agricultural jobs suggested farming exposures (other than pesticides) should be considered as risk factors for Parkinson’s disease.

Authors: Rugbjerg, Kathrine; Harris, M. Anne; Shen, Hui; Marion, Stephen A.; Tsui, Joseph K. C.; Teschke, Kay ;Full Source: Scandinavian Journal of Work, Environment & Health 2011, 37(5), 427-436 (Eng) ;