Environmental and occupational pesticide exposure and human sperm parameters: An updated review

Abstract

Background: In recent decades, global sperm counts have declined, and this has coincided with a proliferation of chemicals with endocrine-disrupting properties to which humans are frequently exposed. Previous reviews of studies published between 1991 through 2013 have reported several associations between environmental and occupational pesticide exposure and reduced human sperm quality, specifically adverse relationships between exposure and sperm concentration. Objectives: This review critically evaluated the current body of evidence associating sperm quality with contemporary pesticide exposure in epidemiological studies. Methods: We conducted a systematic literature review using the Navigation Guide systematic review framework. PubMed, Scopus, and Web of Science databases were searched for all English-language articles published since September 2012. Only original observational studies that assessed human sperm quality parameters and individual-level pesticide exposure data were included. Discussion: Eleven studies assessing environmental or occupational pesticide exposure and sperm parameters were included. Nine (82%) of these studies found at least one significant association with reduced sperm quality, specifically sperm concentration, motility, morphology, and DNA integrity. The quality of evidence was determined to be “moderate” following Navigation Guide protocol, but consistent negative effect estimates and alignment with the results of previous reviews led to the determination that there is sufficient evidence that pesticide exposure adversely affects sperm quality. Conclusion: Taken together with the results of previous reviews, which found significant negative associations between pesticide exposure and sperm quality in 13 of 20 studies published between 1991 and 2008, and in 14 of 17 studies published between 2008 and 2012, this review provides strong evidence associating pesticide exposure with reduced sperm quality. Actions should be taken to reduce global pesticide exposure.