People in the United States and around the world are widely exposed to
pyrethroid pesticides. However, little is known about the effect of
pyrethroids exposure on
obesity in adults. This study examined the association between
pyrethroids exposure and
obesity in males and females and the role of
obesity in the association of
pyrethroids exposure with diabetes and
cardiovascular disease (CVD). We used data from the National Health and Nutrition Examination Survey 1999-2002 and 2007-2014. Multivariate linear regression and logistic regression models were fitted to assess the association between urinary
3-Phenoxybenzoic Acid (3-PBA, a validated
biomarker for
pyrethroids exposure used in the primary analysis) and
obesity. Mediation analyses were performed to investigate the mediation role of
obesity on the associations of
3-PBA with diabetes and CVD. In this analysis, 7896 participants aged 20 years and above were included, of which 1235 (32.2%) males and 1623 (39.9%) females were diagnosed as obese. There was a significant interaction between sex and
3-PBA (Pinteraction = 0.004) for the risk of
obesity. Among females, participants in the highest tertile of urinary
3-PBA had higher odds of
obesity (OR = 1.22, 95% CI: 1.00, 1.48) compared to those in the lowest tertile after adjusting for covariates. Among males, the association was not statistically significant. Similar trends were found in the associations of log-transformed urinary
3-PBA level with body mass index in males and females. Further, we found that, in males and females,
obesity explained the effect of
3-PBA exposure on diabetes by 1.1% (P = 0.850) and 13.6% (P = 0.004), as well as
cardiovascular diseases by 5.9% (P = 0.785) and 25.0% (P = 0.016), respectively. In conclusion,
3-PBA was significantly associated with a higher risk of
obesity, especially in females. In addition,
obesity partially mediated the associations of
3-PBA exposure with diabetes and CVD.