The urinary metabolites of volatile organic compounds and asthma in young children: NHANES 2011-2018

Abstract

Background: Volatile organic compounds (VOCs) are synthetic chemicals that are broadly used in the production of numerous day-to-day products for residential and commercial-based applications. Evidence evaluating the prospective association between volatile organic compounds (VOCs) exposure and asthma in the U.S. children is limited. This study aimed to explore the associations between metabolites of VOCs (mVOCs) in urine, a representative of the internal exposure level of VOCs, and childhood asthma. Methods:We conducted the cross-sectional analysis in 1559 children aged 3-12 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2011-2018. In this study, we investigated the relationship between childhood asthma and urinary concentrations of five volatile organic compound metabolites, including N-Acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA), N-Acetyl-S-(3-hydroxypropyl)-L-cysteine (3HPMA), N-Acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine (HPMMA), N-Acetyl-S-(benzyl)-L-cysteine (SBMA) and 2-Methylhippuric acid (2MHA). These metabolites correspond to the parent compounds acrolein, crotonaldehyde, toluene and xylene, respectively. Adjusted logistic regression models were used to assess the relationship between mVOCs and childhood asthma, followed by a stratified analysis. Results: Urine measurements of mVOCs were weakly associated with an increased odds of childhood asthma, including 2MHA (OR:1.1; 95% CI:0.8, 1.6), SBMA (OR:1.2; 95% CI:0.8, 1.7), CEMA (OR:1.1; 95% CI:0.6, 1.7), 3HPMA (OR:1.1; 95% CI:0.7, 1.8), and HPMMA (OR:1.2; 95% CI:0.7, 2.0). Among female children, 2MHA in urine was significantly associated with the prevalence of asthma (OR: 1.8 95% CI: 1.1, 3.1)). Gender modified associations between urinary 2MHA, but not other urinary mVOCs concentrations, and odds of childhood asthma (gender x 2MHA interaction term p-value = 0.02). Age and race/ethnicity did not modify these associations. Conclusion: We observed some evidence that urinary mVOCs concentrations are associated with increased asthma prevalence in US children, especially urinary 2MHA is significantly associated with the prevalence of asthma in female children. Further studies are needed to fully understand the potential role of VOCs in childhood asthma