Drinking water lead and socioeconomic factors as predictors of blood lead levels in New Jersey's children between two time periods.

As blood lead levels have decreased over time, the relative contributions of alternative lead sources warrant further examination. Much attention has been paid to the relative contribution of lead in drinking water, particularly after the discovery of contaminated drinking water in Flint, Michigan which has also renewed interest in the persistent socioeconomic and racial disparities in children's exposure to lead. As the environmental sources of lead exposure are shifting in importance over time, we decided to examine how demographic, socioeconomic, and environmental factors may confound or interact with each other, and whether these relationships have changed over time. The study population included all New Jersey resident children aged 6-26 months with at least one blood lead specimen collected between 2000 and 2004 (n = 288,758) or 2010 and 2014 (n = 326,530). Reported 90th percentile water lead data (in parts per billion) was summarized annually for each water system statewide. Children's blood lead levels have decreased over time from a statewide geometric mean of 2.47 µg/dL (95% CI 2.46, 2.48) between 2000 and 2004 to 1.57 µg/dL (95% CI 1.57, 1.57) between 2010 and 2014. Individual-level factors of child's age and season of blood draw and area-based measures of race, older housing, and poverty were predictors of children's blood lead levels. Conclusions regarding area-based measure of Hispanic ethnicity are limited and require further research. The narrow range and low levels of area-based lead concentrations in drinking water limits the ability to detect associations with blood lead levels. Racial disparities in blood lead continue to persist but economic disparities may be narrowing as blood lead concentrations continue to decline.