Reconnaissance of Mixed Organic and Inorganic Chemicals in Private and Public Supply Tapwaters at Selected Residential and Workplace Sites in the United States

Safe
drinking water at the point-of-use (tapwater, TW) is a United
States public health priority. Multiple lines of evidence were used
to evaluate potential human health concerns of 482 organics and 19
inorganics in TW from 13 (7 public supply, 6 private well self-supply)
home and 12 (public supply) workplace locations in 11 states. Only
uranium (61.9 μg L–1, private well) exceeded
a National Primary Drinking Water Regulation maximum contaminant level
(MCL: 30 μg L–1). Lead was detected in 23
samples (MCL goal: zero). Seventy-five organics were detected at least
once, with median detections of 5 and 17 compounds in self-supply
and public supply samples, respectively (corresponding maxima: 12
and 29). Disinfection byproducts predominated in public supply samples,
comprising 21% of all detected and 6 of the 10 most frequently detected.
Chemicals designed to be bioactive (26 pesticides, 10 pharmaceuticals)
comprised 48% of detected organics. Site-specific cumulative exposure–activity
ratios (∑EAR) were calculated for the 36 detected
organics with ToxCast data. Because these detections are fractional
indicators of a largely uncharacterized contaminant space, ∑EAR in excess of 0.001 and 0.01 in 74 and 26% of public supply
samples, respectively, provide an argument for prioritized assessment
of cumulative effects to vulnerable populations from trace-level TW
exposures.