Pyrethroid insecticide metabolites are associated with serum hormone levels in adult men.

Experimental studies have reported that pyrethroid insecticides affect male endocrine and reproductive function, but human data are limited. We recruited 161 men from an infertility clinic between years 2000-2003 and measured serum reproductive and thyroid hormone levels, as well as the pyrethroid metabolites 3-phenoxybenzoic acid (3PBA) and cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA and trans-DCCA) in spot urine samples. When adjusting for potential confounders, categories for all three metabolites, as well as their summed values, were positively associated with FSH (all p-values for trend <0.05). Statistically significant or suggestive positive relationships with LH were also found. In addition, cis-DCCA and trans-DCCA were inversely associated with inhibin B (p for trend=0.03 and 0.02, respectively). Finally, there was evidence that trans-DCCA was inversely associated with testosterone and free androgen index (the ratio of testosterone to sex hormone binding globulin; p for trend=0.09 and 0.05, respectively). The observed relationships were consistent with previous findings, but further research is needed for a better understanding of the potential association between pyrethroid insecticides and male reproduction.