Occupational pesticide exposure and risk of Parkinson’s disease: protocol for a systematic review and meta-analysis

Introduction Parkinson’s disease is a rapidly increasing neurological disorder in terms of global prevalence and is associated with disability and reduced quality of life. Occupational exposure to pesticides has long been considered a potential risk factor, but there is a lack of a systematic review attempting to derive the exposure–response relationship. This protocol outlines the planned methodology for a systematic review and where feasible, meta-analysis to evaluate the relationship between occupational pesticide exposure and Parkinson’s disease. Methods and analysis We will include epidemiological studies (cohort, case–control and cross-sectional studies) examining the relationship between occupational pesticide exposure and Parkinson’s disease in adults of working age or older. Exposure may be assessed via self-report, expert assessment, job exposure matrices, direct observation or technical measurements. Eligible outcomes are clinically confirmed Parkinson’s disease. The literature search will be conducted in PubMed, Embase, Web of Science, NIOSHTIC-2 and ArbLINE, supplemented by grey literature. Two reviewers will independently screen studies, extract data and assess risk of bias. Where feasible, effect estimates will be pooled using random-effects meta-analysis and explored through sensitivity analyses. We will evaluate the certainty of evidence using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach. Ethics and dissemination As this review is based solely on published data, ethical approval is not necessary. Results will be disseminated through a peer-reviewed publication and relevant scientific meetings. PROSPERO registration number CRD1089055.