Association of pyrethroids exposure with asthma in US children and adolescents: a nationally representative cross-sectional study

Pyrethroids (PYR) are among the most widely used insecticides in households, leading to substantial exposure. Children and adolescents, especially during growth spurts, have a reduced capacity to effectively metabolize these insecticides. The relationship between PYR exposure and asthma in these age groups remains poorly understood, highlighting the need for further research. We used data from the 2007-2014 National Health and Nutrition Examination Survey, which included 1181 children aged 6-11 years and 1258 adolescents aged 12-19 years. The concentration of the PYR metabolite 3-phenoxybenzoic acid (3-PBA) in urine was quantified using solid-phase extraction-high-performance liquid chromatography-heated electrospray ionization tandem mass spectrometry. Asthma was defined based on self-reported doctor diagnoses from the questionnaire. PYR exposure was measured using urine samples collected simultaneously with the questionnaire. We explored the association between PYR exposure and asthma using multiple logistic regression analyses, adjusting for potential confounders. Multiple logistic regression analyses revealed no significant association between PYR exposure and asthma in children and adolescent boys (all P > 0.05). In contrast, PYR exposure was significantly associated with asthma in adolescent girls aged 12-19 years. Specifically, for "ever asthma," the odds ratios (ORs) were 2.49 (95% CI = 1.03-5.97) in the second quartile of PYR exposure and 2.48 (95% CI = 1.04-5.91) in the third quartile, each in comparison to the first quartile. For "current asthma," in comparison to the first quartile, the ORs were 3.99 (95% CI = 1.55-10.26) in the second quartile of PYR exposure, 3.39 (95% CI = 1.32-8.70) in the third quartile, and 2.93 (95% CI = 1.24-6.90) in the fourth quartile. Conclusions: Our study found a significant association between PYR exposure and asthma in adolescent girls, whereas no significant association was observed in children and adolescent boys. These findings suggest potential sex and age differences in susceptibility to PYR exposure. Further research is warranted to confirm these results and elucidate the underlying mechanisms.