Metals in tap water across child care and home environments: association between lead and early childhood executive function

BACKGROUND: Metals, including lead, are frequently detected in tap water. Biomarker-based studies link elevated levels of lead with poorer child cognitive outcomes, including executive function (EF) skills. Nevertheless, few studies have characterized metal exposures in child care center and home water samples or examined whether tap water concentrations of lead alone are associated with child EFs. OBJECTIVE: We aimed to (1) characterize metal concentrations in tap water from child care kitchens, classrooms, and homes, (2) identify sociodemographic and environmental predictors of waterborne lead, and (3) test associations between lead and child EF skills. METHODS: Tap water from 51 North Carolina (NC) child care kitchens, 120 classrooms, and 138 homes of 297 children (2-6 years old) were collected and analyzed for 15 metals via EPA Method 200.8. Child EF skills were assessed through a performance-based assessment and a parent questionnaire. Regression models related waterborne lead to sociodemographic characteristics and water source. Path models evaluated associations between lead from samples in each setting and EF skills. RESULTS: Lead was detected in 67% of child care kitchen, 34% of classroom, and 57% of home kitchen drinking water samples. While 8% of child care kitchen, 3% of classroom, and 7% of home kitchen water samples exceeded the American Academy of Pediatrics reference level of 1 part per billion (ppb) for lead, none exceeded the NC state action level and U.S. Environmental Protection Agency standard of 10 ppb. Lead concentration in child care kitchen water was negatively associated with inhibitory control. SIGNIFICANCE: Metals were frequently detected in child care center and home water samples. Although waterborne lead concentrations were below the state action level, child care kitchen lead was negatively associated with child EF skills. IMPACT STATEMENT: Key metals, including lead, were frequently detected in water samples collected from child care kitchens (N = 51), classrooms (N = 120), and homes (N = 138) of children ages 2-6 years old. Though lead levels were below state and federal guidelines, the waterborne lead in the child care center was negatively associated with children's executive function skills (N = 297). The absence of a link between home water lead and children's executive function skills may stem from selection bias, as families at higher risk for lead were underrepresented in home sample collection. The results underscore the frequency of exposure to, and potential impact of, neurotoxic contaminants in children's daily environments.