Review Occupational exposure to pesticides and Parkinson's disease: A systematic review and meta-analysis of cohort studies Geneviève Van Maele-Fabry ⁎, Perrine Hoet, Fabienne Vilain, Dominique Lison Université catholique de Louvain, SSS/IREC/LTAP, Louvain Center for Toxicology and Applied Pharmacology, Avenue E. Mounier 52, bte B1.52.12, B-1200 Brussels, Belgium abstract article info Article history: Received 20 February 2012 Accepted 17 May 2012 Available online 13 June 2012 Keywords: Parkinson Occupational exposure Pesticides Systematic review Meta-analysis Cohort studies Objectives: To systematically review available cohort studies and estimate quantitatively the association be- tween occupational exposure to pesticides and Parkinson's disease (PD). Methods: Studies were identified from a MEDLINE search through 30 November 2011 and from the reference lists of identified publications. Relative risk (RR) estimates were extracted from 12 studies published be- tween 1985 and 2011. Meta-rate ratio estimates (mRR) were calculated according to fixed and random- effect meta-analysis models. Meta-analyses were performed on the whole set of data and separate analyses were conducted after stratification for gender, exposure characterisation, PD cases identification, geographic location, reported risk estimator and cohort study design. Results: A statistically significant increased risk of PD was observed when all studies were combined (mRR = 1.28; 95% confidence interval [CI]: 1.03–1.59) but there was a high heterogeneity and inconsistency among studies. The highest increased risks were observed for studies with the best design, i.e. reporting PD diagnosis confirmed by a neurologist (mRR = 2.56; CI: 1.46–4.48; n = 4), for cohort studies reporting inci- dence of PD (mRR = 1.95; CI: 1.29–2.97; n = 3) as well as for prospective cohorts (mRR = 1.39; CI: 1.09– 1.78; n = 6). A significant increased risk was also seen for banana, sugarcane and pineapple plantation workers (mRR = 2.05; CI: 1.23–3.42; n = 2). Conclusions: The present study provides some support for the hypothesis that occupational exposure to pes- ticides increases the risk of PD. © 2012 Elsevier Ltd. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2. Materials and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.1. Study identification and selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.1.1. Study identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.1.2. Study selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.2. Data extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3. Data analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3.1. Evaluation of homogeneity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3.2. Statistical pooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3.3. Publication bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3.4. Sensitivity analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.1. Literature selection and study characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.2. Data synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.2.1. Meta-analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.2.2. Sensitivity analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.2.3. Funnel plot and asymmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Environment International 46 (2012) 30–43 Abbreviations: 95% CI, 95% confidence interval; HR, hazard ratio; HWE, healthy worker effect; mRR, meta-rate ratio estimate; PD, Parkinson's disease; PMR, proportional mor- tality ratio; PR, prevalence ratio; RR, relative risk; SHR, standardized hospitalization (for PD) ratio; SMR, standardized mortality ratio; 95% UI, 95% uncertainty interval. ⁎ Corresponding author. Tel.: +32 2 764 53 40; fax: +32 2 764 53 38. E-mail address: genevieve.vanmaele@uclouvain.be (G. Van Maele-Fabry). 0160-4120/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.envint.2012.05.004 Contents lists available at SciVerse ScienceDirect Environment International journal homepage: www.elsevier.com/locate/envint