Organophosphorus insecticides exposure and sex hormones in general U.S. population: A cross-sectional study

Evidence showed organophosphorus (OPs) insecticide exposure is common in general population with endocrine-disrupting effects. However, the association between OPs metabolites and sex hormones remains unclear. To investigate the association between OPs metabolites and sex hormones. Data of 1438 participants from NHANES 2015–2016 was applied. Urinary OPs metabolites, dialkyl phosphates (DAPs), and serum sex hormones (total testosterone (TT), estradiol (E2), and sex hormone-binding globulin (SHBG)) were measured. Free androgen index (FAI) and TT/E2 ratio were also calculated. The generalized linear regression model and restricted cubic spline (RCS) model were employed to evaluate the association and exposure-response curve of DAPs and sex hormones in males and females. The modulation effect of age on their associations in female participants was also explored. After adjusting for confounding factors, DETP was negatively associated with E2 (β = −0.03; 95% CI: −0.05, −0.01) and FAI (β = −0.03; 95% CI: −0.06, −0.001) in males. In females, all the four DAP metabolites (DMP, DEP, DMTP, and DETP) were negatively associated with FAI (DMP: β = −0.06, 95% CI: −0.11, −0.01; DEP: β = −0.06, 95% CI: −0.12, −0.01; DMTP: −0.05, 95% CI: −0.09, −0.02; DETP: −0.09, 95% CI: −0.14, −0.04). DETP was also found negatively associated with TT and TT/E2 ratio in females. The associations between DETP and TT, FAI, and TT/E2 ratio were modified by gender (Pinteraction<0.05). RCS analysis found these associations were in linear decreased exposure-response curves. For females of different age groups, the inverse associations of DETP with TT and FAI remained stable. Decreased FAI with DMP and DMTP was also found in females ≤50 years old. Our study indicates OPs metabolites had negative associations with androgen indicators, which was characterized as decreased FAI and E2 in males and decreased TT, FAI, and TT/E2 ratio in females, particularly among females ≤50 years old. Further studies are warranted in larger-scale populations.