Urinary 3-Phenoxybenzoic Acid in U.S. Children and Adolescents: Temporal and Demographic Patterns in NHANES, 1999–2002 and 2007–2018

Background: Pyrethroid pesticides are widely used, and children may experience exposure through multiple nonoccupational pathways. Urinary 3-phenoxybenzoic acid (3-PBA) is a commonly used biomarker of recent pyrethroid exposure. Methods: In this repeated cross-sectional analysis, we analyzed U.S. National Health and Nutrition Examination Survey (NHANES) data for participants aged 3–19 years from 1999–2002 and 2007–2018. Urinary 3-PBA data were unavailable for 2003–2006. Descriptive statistics for urinary 3-PBA concentrations were creatinine-corrected and estimated by age group and survey cycle. For regression analyses, urinary 3-PBA concentrations were not creatinine-corrected; instead, log-transformed urinary 3-PBA was modeled with urinary creatinine included as a covariate, along with survey cycle, age group, sex, race/ethnicity, and poverty–income ratio (PIR). Analyses incorporated subsample weights with SUDAAN software. Results: Among 7415 U.S. children and adolescents, the overall creatinine-corrected geometric mean urinary 3-PBA concentrations were 0.31 [95% CI: 0.25, 0.39] and 0.93 [0.80, 1.08] µg/g creatinine for survey cycles 1999–2000 and 2017–2018, respectively. Concentrations were higher in younger children than in older children. Urinary 3-PBA concentrations were generally higher in later survey cycles. Adjusted models showed that urinary 3-PBA concentrations were higher among younger children and children from lower-income households and were lower among non-Hispanic Black, Mexican American, and Other race/ethnicity groups compared with non-Hispanic White children. Survey cycle was positively associated with urinary 3-PBA in the 1999–2002 and 2007–2014 model but was not statistically significant in the 2015–2018 model. Sex was not consistently associated with urinary 3-PBA across the two analytic periods. Conclusions: Recent pyrethroid exposure, as reflected by urinary 3-PBA, was widespread and socially patterned among U.S. children and adolescents. Urinary 3-PBA varied by age group, survey cycle, race/ethnicity, and poverty–income ratio. These findings should be interpreted as exposure surveillance data rather than evidence of specific health effects. Ongoing biomonitoring, source-focused research, and studies with repeated exposure assessments would help to better understand the factors influencing pyrethroid exposure and its public health significance in children.