Introduction Organophosphate (OP) pesticides exposure has been linked to various health effects but the association between exposure and semen quality is unclear. This systematic review aimed to investigate the association between OP exposure and semen quality.

Methods Electronic databases including Ovid-Medline, PubMed and Website of Science were searched for studies on OP and semen quality published between 2000 and 2016. Terms representing population, exposure and outcome were used in combination. Relevant articles were extracted and critically appraised using the Newcastle Ottawa Scale.

Results 12 epidemiological studies were identified of which 10 were cross- sectional and two case-control studies. Eight studies were of occupationally exposed workers with exposure assessed by self-report in four studies or inferred in three studies or by the use of urinary dialkylphosphates in five studies. Sperm concentration or motility or morphology was altered in eight studies. Concentration was reduced in one study of which assessed exposure by self-report, one by inference and three by biomarkers. Motility was reduced in four studies of which assessed exposure by self-report, one by inference and two by biomarkers. Morphology was reduced in three studies of which assessed exposure by self-report and one by inference. More fundamentally only one study examined the relationship between time of exposure and outcome assessment.

Conclusion There was a lack of consistency in the reported associations and hence there is limited evidence to support a causal association between OP exposure and semen quality. This could be due to heterogeneity in study populations and different in exposure assessment