Citation:

Schroeder, A., G. Ankley, B. Blackwell, K. Houck, AND Dan Villeneuve. Characterizing the bioactivity of complex environmental samples using high throughput toxicology. SETAC, North America, Salt Lake City, UT, November 01 - 05, 2015.

Impact/Purpose:

not applicable

Description:

Bioassays can be employed to evaluate the integrated effects of complex mixtures of both known and unidentified contaminants present in environmental samples. However, such methods have typically focused on one or a few bioactivities despite the fact that the chemicals in a mixture may exhibit a wide range of activities. High throughput toxicology approaches that can rapidly screen samples for a broad diversity of biological activities offer a means to provide a more comprehensive characterization. To test this concept, twenty-four ambient water samples were collected, extracted, and screened for their ability to interact with or modulate over 80 different transcription factors using the Attagene subset of assays utilized by the US EPA’s ToxCast Program. Samples evaluated included water collected at five sites along a spatial gradient centered around a wastewater discharge into the Maumee River, Ohio, USA; 10 samples were collected in varying proximity to a wastewater discharge within the St. Louis River Area of Concern (AOC), MN; and eight samples were associated with a nation-wide US Geological Survey Mixture Study. Samples collected along the Maumee River showed a gradient response in the number of observed activities, ranging from three positive assay responses observed far upstream of discharge to seven positive responses in water from the mixing zone. TGFb signaling and the aryl hydrocarbon receptor (AhR) activation were the biological activities observed at the lowest sample concentration (greatest dilution). At the St. Louis River AOC, the greatest number of biological activities were observed at locations closest to wastewater discharge with as many as 13 endpoints responding. For the USGS mixture study sites, the number of positive responses ranged from 2 for a sample collected from the Iowa River, IA to 15 for a sample collected from the South Platte River, CO. Estrogen response elements and the AhR were activated at the lowest sample concentration. The biological activities identified for each site can now be mapped to established adverse outcome pathways to predict potential hazards to aquatic biota and/or selecting endpoints for subsequent site-specific effects monitoring.

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