ASSESSING THE SCOPE OF LEAD CONTAMINATION IN PUBLIC SCHOOL DRINKING WATER IN INDIANA, USA

In 2017-2018, Indiana conducted voluntary statewide drinking water sampling in public schools to screen for lead (Pb) contamination. The program enrollment represented 60% of public-school children in Indiana. Children are especially vulnerable to lead poisoning, and ingestion of Pb in drinking water can contribute up to 20% of their exposure to lead. In total, all drinking-water fixtures in 915 K-12 schools (out of 1709 eligible schools) were sampled using standardized protocols designed to assess both fixtures and school plumbing infrastructure, totaling 58,000 water samples. Censored data methods were used to analyze the data by sample draw type (i.e., initial/stagnant draw versus flushed samples). Although regulatory measures are initiated at an action level of 15 ppb of Pb in drinking water for community water systems, there is no safe level of Pb in drinking water; so this study also evaluated the prevalence of contamination at lower concentrations. 62% of schools had at least one drinking-water fixture that exceeded a Pb concentration of 15 ppb, while 7% of schools had more than 10 fixtures with Pb concentrations >15 ppb. However, contamination is clearly even more widespread if evaluated at a level of 5 ppb, with 87% of schools having at least one contaminated fixture, and 28% having more than 10 fixtures with elevated Pb levels. For the entire population of fixtures sampled, the mean initial draw concentration was 7.8 ppb (median 0.9 ppb). Sampling protocols functioned as designed with the initial draw samples able to differentiate between different fixture types. The results reinforce findings from other studies in that fixtures not intended for drinking water (e.g., athletic facilities using spigots or hoses), seasonal, or infrequently used fixtures (including kitchen appliances) showed the highest Pb concentrations. In contrast, fixtures with filters or without storage tanks or clogged aerators had the lowest Pb concentrations. The study also includes additional inquiry into the spatial distribution of results and the potential role of source water (e.g., surface or groundwater) on water quality in Indiana public schools.