SusChEM: GOALI: Drinking Water Safety and Sustainability: Identifying Key Chemical Drivers of Toxicity for Long-Term Solutions in the United States

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Collaborative ProposalPIs: Susan D. Richardson/Michael PlewaProposal Number: 1705206/1706862The majority of citizens in the US consume disinfected water. Chemical disinfectants inactivate pathogens in drinking water; however, an unintended consequence is their reaction with natural organic matter (NOM), anthropogenic contaminants, and bromide/iodide to form disinfection by-products (DBPs). For our drinking water supplies, a wide range of pristine and impacted waters are used, where high levels of certain emerging DBPs of concern have been reported. As a result, DBPs represent a ubiquitous chronic chemical exposure, yet the forcing agents for toxicity remain unknown. This research will address this knowledge gap, serve as the basis for a future wider International DBP study, and create a new paradigm for drinking water regulation to enhance drinking water safety and sustainability. The PIs will employ the on-going academic programs at their universities to provide research experiences for undergraduate and high school students, in particular students from underrepresented groups. An international group of leading scientists participating at the 2015 Gordon Research Conference on Drinking Water Disinfection By-Products met to address these issues and recommended an International DBP study to (1) evaluate DBP levels globally, focusing on key emerging DBPs and surrogate parameters: total organic chlorine (TOCl), total organic bromine (TOBr), total organic iodine (TOI), and (2) determine which subsets of DBPs are the forcing agents of toxicity. The PIs seek to accomplish these goals in an initial assessment in the US. Results from this research will generate data to better understand DBP risks, determine the forcing agents of toxicity, and enable long-term engineering solutions to enhance drinking water safety and sustainability. This research will identify the drivers of in vitro toxicity as a metric of potential human health risk for DBPs in drinking water from the United States and will serve as the basis for a future International DBP study that will globally assess DBP risks. While it is widely recognized that individual bromine- and iodine-containing DBPs are more toxic than their chlorine-containing analogues, the correlation of TOCl, TOBr, and TOI with a wide range of individual DBPs has not been evaluated. These chemical surrogates are recognized as holding great potential (especially TOBr and TOI) for accounting for risk, both from known DBPs (including the 65 priority DBPs to be quantified in this study) and the unknown DBPs, where 50% of the total organic halogen (TOX) content has yet to be identified. The Environmental Protection Agency (EPA) has expressed interest in the potential to use these kinds of surrogates for regulation if they adequately represent the adverse health risk from halogenated DBPs. Thus, this research also has the potential to modify regulations as we know them today and better protect human health and enable global, safe, and sustainable drinking water.