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Expanded Target-Chemical Analysis Reveals Extensive Mixed-Organic-Contaminant Exposure in U.S. Streams
Citation:
Bradley, P., C. Journey, K. Romanok, L. Barber, H. Buxton, W. Foreman, E. Furlong, S. Glassmeyer, M. Hladik, L. Iwanowicz, D. Jones, D. Kolpin, K. Kuivila, K. Loftin, M. Mills, M. Meyer, J. Orlando, T. Reilly, K. Smalling, AND Dan Villeneuve. Expanded Target-Chemical Analysis Reveals Extensive Mixed-Organic-Contaminant Exposure in U.S. Streams. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 51(9):4792–4802, (2017).
Impact/Purpose:
Assessment and management of risks associated with exposure to complex mixtures of contaminants in surface waters is a priority for environmental health organizations around the world. However, information on the composition and variability of mixtures detected in surface water and their potential effects on aquatic ecosystems and/or humans relying on ecosystem services is limited. To address this, the US Geological Survey (USGS) and US EPA undertook a collaborative study to survey surface waters from 38 streams nationwide for chemical contaminants and biological activity. The present paper reports on analytical characterization of those samples by USGS. The paper examined the occurrence and concentrations of over 700 target analytes in surface waters from a broad range of streams representing a gradient of urban, agriculture, and un-developed land use, a broad range of geologies and ecoregions, and multiple EPA regions. The most common analytes detected, variation in composition with regard to land-use, and association with major sources is reported. These data will be directly compared with bio-effects data generated by EPA authors (to be reported in separate publications) in order to associate chemicals present in these complex surface water mixtures with specific biological activities and potential effects. These results contribute to on-going efforts to understand the potential hazards and risks associated with contaminants of emerging concern in surface waters, which is of direct interest to the Office of Water, EPA Regional Offices, the Great Lakes National Program offices, States and Tribes and other entities. Additionally, the work supports the goals of the Chemical Safety for Sustainability program, to effectively utilize pathway-based biological effects data to aid environmental risk assessment.
Description:
Surface-water from 38 streams nation-wide was assessed using 14 target-organic methods (719 compounds). Designedbioactive anthropogenic contaminants (biocides, pharmaceuticals) comprised 57% of 406 organics detected at least once. The 10 most-frequently detected anthropogenic-organics included 8 pesticides (desulfinylfipronil, AMPA, chlorpyrifos, dieldrin, metolachlor, atrazine, CIAT, glyphosate) and 2 pharmaceuticals (caffeine, metformin) with detection frequencies ranging 66-84% of all sites. Detected contaminant concentrations varied from less than 1 ng L-1 to greater than 10 µg L-1, with 77 and 278 having median detected concentrations greater than 100 ng L-1 and 10 ng L-1, respectively. Cumulative detections and concentrations ranged 4-162 compounds (median 70) and 8.5-102,847 ngL-1, respectively, and correlated significantly with wastewater discharge, watershed development, and Toxic Release Inventory metrics. Log10 concentrations of widely-monitored HHCB, triclosan, and carbamazepine explained 71%-82% of the variability in the total number of compounds detected (linear regression; p-values: <0.001-0.012), providing a statistical inference tool for unmonitored contaminants. Due to multiple modes of action, high bioactivity, biorecalcitrance, and direct environment application (pesticides), designed-bioactive organics (median 41 per site at µg L-1 cumulative concentrations) in developed watersheds are aquatic health concerns, given their acknowledged potential for sub-lethal effects to sensitive species and lifecycle stages at low ng L-1.
