A national survey of lead and other metal(loids) in residential drinking water in the United States

Background: Exposure to lead (Pb), arsenic (As) and copper (Cu) may cause significant health issues including harmful neurological effects, cancer or organ damage. Determination of human exposure-relevant concentrations of these metal(loids) in drinking water, therefore, is critical.

Objective: We sought to characterize exposure-relevant Pb, As, and Cu concentrations in drinking water collected from homes participating in the American Healthy Homes Survey II, a national survey that monitors the prevalence of Pb and related hazards in United States homes.

Methods: Drinking water samples were collected from a national survey of 678 U.S. homes where children may live using an exposure-based composite sampling protocol. Relationships between metal(loid) concentration, water source and house age were evaluated.

Results: 18 of 678 (2.6%) of samples analyzed exceeded 5 µg Pb L^-1 (Mean = 1.0 µg L^-1). 1.5% of samples exceeded 10 µg As L^-1 (Mean = 1.7 µg L^-1) and 1,300 µg Cu L^-1 (Mean = 125 µg L^-1). Private well samples were more likely to exceed metal(loid) concentration thresholds than public water samples. Pb concentrations were correlated with Cu and Zn, indicative of brass as a common Pb source is samples analyzed.

Significance: Results represent the largest national-scale effort to date to inform exposure risks to Pb, As, and Cu in drinking water in U.S. homes using an exposure-based composite sampling approach.

Impact statement: To date, there are no national-level estimates of Pb, As and Cu in US drinking water collected from household taps using an exposure-based sampling protocol. Therefore, assessing public health impacts from metal(loids) in drinking water remains challenging. Results presented in this study represent the largest effort to date to test for exposure-relevant concentrations of Pb, As and Cu in US household drinking water, providing a critical step toward improved understanding of metal(loid) exposure risk.