Is dietary pesticide exposure related to semen quality? Positive evidence from men attending a fertility clinic.

Chiu and her colleagues from Harvard School of Public Health and Massachusetts General Hospital present important new data on semen quality in relation to dietary pesticide exposure via fruit and vegetable intake (Chiu et al., 2015). To examine this relationship the authors utilized a novel approach that classifies fruits and vegetables into high versus low-to-moderate pesticide residue groups based on data from the United States Department of Agriculture (USDA) Pesticide Data Program (PDP). Data obtained from a validated food frequency questionnaire (FFQ) combined with USDA PDP yielded individual measures of intake of fruits and vegetables with higher pesticide residues. The authors found that semen quality was reduced among men in the highest quartile of exposure, a finding which could have clinical and public health implications. Pesticides are designed to be biocides and an extensive literature demonstrates that many of these chemicals adversely impact human reproductive function. It has long been known that occupational exposure to certain pesticides have a devastating effect on semen quality and male fertility. For example plantation workers exposed to the nematocide 1,2-dibromo-3-chloropropne (DBCP)were rendered azoospermic (Whorton et al., 1977). However, studying the subtler effects of non-occupational pesticide exposure on semen quality remains a challenge that is addressed by Chiu and colleagues using a novel method of exposure assessment. Their compelling results justify a discussion of methodological issues and public health implications.