Disinfection Byproducts and Inorganic Contaminants in the U.S. Correctional Facility Public Water Systems

Few studies have evaluated drinking water contaminants for people incarcerated in the United States. We predicted that community water systems (CWSs) that exclusively serve correctional facilities would report elevated contaminant concentrations compared to all other CWSs.

Concentrations of inorganic contaminants (arsenic, chromium, fluoride, nitrate, uranium) and disinfection byproducts (total trihalomethanes and haloacetic acids) were derived from routine compliance monitoring records in the U.S. Environmental Protection Agency's (EPA) Six-Year Review database. We evaluated adjusted geometric means and 90th percentile differences of 2017-2019 average concentrations of inorganic contaminants and disinfection byproducts for 194 correctional facility CWSs (serving 437,394 people) and 42,434 other CWSs. We calculated the population served by correctional facility CWSs equal to or exceeding the U.S. EPA's maximum contaminant level nationwide, by region, and by seasonal monitoring periods.

In the Southwest, correctional facility CWSs reported higher arsenic concentrations (adjusted geometric mean 2.75 μg/L, 95% CI 1.46, 5.19) compared to all other CWSs (1.06 μg/L, 95% CI 1.03, 1.09; p value < 0.001) and higher adjusted 90th percentile arsenic concentrations. In fall, nationwide adjusted 90th percentile concentrations were higher for total trihalomethanes (difference 15.2 μg/L, 95% CI 11.3, 19.2) and haloacetic acids (12.3 μg/L, 95% CI 10.6, 13.9) in correctional facility CWSs compared with all other CWSs.

We identified regional and seasonal inequities in regulated drinking water contaminants impacting people incarcerated in the United States. Comparing our findings to those previously published, inequities in arsenic exposure for people incarcerated in the Southwest have improved since 2006, supporting that regulatory, enforcement, and legal actions have reduced exposures.