Objectives: The evidence interpreting the association between environmental pyrethroid exposure and asthma is limited. The objective of this study was to examine the association between pyrethroid exposure and asthma among U.S. children and adults.
Methods: Participants were collected from the National Health and Nutrition Examination Survey (NHANES, 2007-2014), including children and adults. 3-phenoxybenzoic acid (3-PBA) was used as a biomarker for pyrethroid metabolites. Multiple logistic regression models were constructed to estimate the association of urinary 3-PBA with asthma among children and adults and to calculate odds ratios (ORs) and corresponding 95% confidence intervals (CIs). Additionally, a restricted cubic spline plot with three knots was applied to assess the potential nonlinear relationship between pyrethroid exposure and asthma.
Results: Collectively, 7,776 participants were enrolled, including 2,236 children and 5,540 adults. The weighted prevalence of asthma in children and adults was 12.23% and 8.66% respectively. After adjusting for age, sex, race/ethnicity, poverty income ratio (PIR), body mass index (BMI), serum cotinine, urinary creatinine and family history of asthma, our results indicated that higher levels of 3-PBA was positively related to the risk of asthma among children (OR: 1.395; 95%CI: 0.880, 2.210) and adults (OR: 1.177; 95%CI: 0.778, 1.781). This positive association seemed to be more pronounced among 12-19-years old children and girls. Furthermore, the restricted cubic spline plot showed a linear relationship between levels of 3-PBA and asthma among children and adults (p for nonlinearity was 0.693 and 0.691 respectively).
Conclusions: Our study observed a positive association between 3-PBA and asthma among children and adults while this positive association was more pronounced among children. However, we can not role out the possibility that the possible role of other co-occurring pesticides and other chemicals in the observed trends in asthma incidence. Therefore, further studies are needed to evaluate the possible pathogenic role of pyrethroid insecticides in asthma.