Organochlorine pesticides and prostate cancer, Is there an association? A meta-analysis of epidemiological evidence

The results of epidemiological studies about exposure to organochlorine pesticides (OCPs) and risk of prostate cancer (PC) are inconclusive. We conducted a meta-analysis to evaluate the association between exposure to specific OCPs and PC. We searched PubMed, Scopus, and Web of science databases for case-control and cohort studies published till March 2015 that provided data about exposure to OCPs and PC. We also contacted authors and hand-searched references of the included articles. We calculated pooled estimates using random effects model and explored heterogeneity between studies. We systematically reviewed 15 articles and based our meta-analysis on 10 articles covering nine case-control studies and a large prospective cohort study. Pooled estimates of PC for highest versus lowest exposed category to p,p'-DDE was 1.02 (0.69-1.35), I (2) = 12.7 %, p = 0.333, trans-nonachlor, 0.88 (0.45-1.31), I (2) = 0.00 %, p = 0.892, oxychlordane, 0.91 (0.46-1.35), hexachlorobenzene, 0.88 (0.18-1.57), I (2) = 36.0 %, p = 0.210 from combining results of studies that applied serum OCPs measurements among the general population. For DDT, stratifying studies by exposed population revealed homogeneity, pooled estimate for serum level measurement for the highest exposed versus the lowest exposed of the general population was 0.81 (0.95-1.26), I (2) = 0.00 %, p = 0.400, and for occupational exposure 1.30 (0.94-1.67), I (2) = 13.4 %, p = 0.315. A positive but also insignificant association was obtained for pooling results for high exposure to lindane among farmers and pesticide applicators, 1.56 (0.82-2.29), I (2) = 41.7 %, p = 0.180. The existing epidemiological data do not support the hypothesis that exposure to specific OCPs is associated with an increased incidence of PC in the general population.