Association between urinary 3-phenoxybenzoic acid and body mass index in Korean adults: 1st Korean National Environmental Health Survey

Background: According to US-EPA report, the use of pyrethrins and pyrethroids has increased during the past decade, and their area of use included not only in agricultural settings, but in commerce, and individual household. It is known that urinary 3-PBA, major metabolite of pyrethroid, have some associations with health effect in nervous and endocrine system, however, there's no known evidence that urinary 3-PBA have associations with obesity. Method: We used data of 3671 participants aged above 19 from the Korean National Environmental Health Survey in 2009-2011. In our analysis, multivariate piece-wise regression and logistic regression analysis were used to investigate the association between urinary 3-PBA (3-Phenoxybenzoic Acid) and BMI. Result: Log-transformed level of urinary 3-PBA had significantly positive association with BMI at the low-level range of exposure (p < 0.0001), and opposite associations were observed at the high level exposure (p = 0.04) after adjusting covariates. In piece-wise regression analysis, the flexion point that changes direction of the associations was at around 4 ug/g creatinine of urinary 3-PBA. As quintiles based on concentration of urinary 3-PBA increased to Q4, the ORs for prevalence of overweight (BMI >= 23 kg/m(2)) were increased, and the OR of Q5 was lower than that of Q4 (OR = 1.810 for Q4; OR = 1.483 for Q5). In the analysis using obesity (BMI >= 25 kg/m(2)) as outcome variable, significant associations were observed between obesity and quintiles of 3-PBA, however, there were no differences between the OR of Q5 and that of Q4 (OR = 1.659 for Q4; OR = 1.666 for Q5). Conclusion: Our analysis suggested that low-level of pyrethroid exposure has positive association with BMI, however, there is an inverse relationship above the urinary 3-PBA level at 4 ug/g creatinine.