In vitro bioactivity results analyzed in private, public, and bottled drinking-water samples, 2016-20

Beginning in 2016, the U.S. Geological Survey, Environmental Health Program, Drinking Water and Wastewater Infrastructure Integrated Science Team, in collaboration with other federal, non-governmental and Tribal partners, began collecting and analyzing tapwater samples from across the Nation for a large suite of inorganic, organic, and biological contaminants (Bradley and others, 2025). Results from these analyses demonstrated that, in many instances, drinking water is an exposure pathway for multiple contaminants of concern (exposures greater than the federal and state drinking water health-based guidelines) in private, public, and bottled water sources. In addition to targeted chemical analyses, in vitro bioactivity analyses were performed to help characterize the potential biological effects from multiple contaminants. From 2016-2020, 265 water-quality samples, including 21 quality-assurance field blanks, which had previously been extracted from 1-liter samples were sent to Attagene, Inc., Morrisville, North Carolina for in vitro bioactivity screening. These extracts were analyzed for 48 biological endpoints using the cis-factorial assay described in Romanov and others (2008). Detailed method information and further analysis can be found in the associated report Bradley and others (2026). References-- Bradley, P.M., Romanok, K.M., Smalling, K.L., Gordon, S.E., Huffman, B.J., Friedman, K.P., Villeneuve, D.L., Blackwell, B.R., Fitzpatrick, S.C., Focazio, M.J., Medlock-Kakaley, E., Meppelink, S.M., Navas-Acien, A., Nigra, A.E., and Schreiner, M.L., 2025, Private, public, and bottled drinking water: Shared contaminant-mixture exposures and effects challenge: Environmental International, v. 195, 18 p., accessed on April 29, 2020 2026, at https://doi.org/10.1016/j.envint.2024.109220. Romanov, S., Medvedev, A., Gambarian, M., Poltoratskaya, N., Moeser, M., Medvedeva, L., Gambarian, M., Diatchenko, L., and Makarov, S., 2008, Homogeneous reporter system enables quantitative functional assessment of multiple transcription factors: Nature Methods, v. 5, p. 253-60, accessed on April 28, 2026 at https://doi.org/10.1038/nmeth.1186.