Multi-region assessment of pharmaceutical exposures and predicted effects in USA wadeable urban-gradient streams

Abstract

Human-use pharmaceuticals in urban streams link aquatic-ecosystem health to human health. Pharmaceutical mixtures have been widely reported in larger streams due to historical emphasis on wastewater-treatment plant (WWTP) sources, with limited investigation of pharmaceutical exposures and potential effects in smaller headwater streams. In 2014-2017, the United States Geological Survey measured 111 pharmaceutical compounds in 308 headwater streams (261 urban-gradient sites sampled 3-5 times, 47 putative lowimpact sites sampled once) in 4 regions across the US. Simultaneous exposures to multiple pharmaceutical compounds (pharmaceutical mixtures) were observed in 91% of streams (248 urban-gradient, 32 low-impact), with 88 analytes detected across all sites and cumulative maximum concentrations up to 36,142 ng/L per site. Cumulative detections and concentrations correlated to urban land use and presence/absence of permitted WWTP discharges, but pharmaceutical mixtures also were common in the 75% of sampled streams without WWTP. Cumulative exposure-activity ratios (EAR) indicated widespread transient exposures with high probability of molecular effects to vertebrates. Considering the potential individual and interactive effects of the detected pharmaceuticals and the recognized analytical underestimation of the pharmaceutical-contaminant (unassessed parent compounds, metabolites, degradates) space, these results demonstrate a nationwide environmental concern and the need for watershed-scale mitigation of in-stream pharmaceutical contamination.

Filling in the Gaps in Metformin Biodegradation: a New Enzyme and a Metabolic Pathway for Guanylurea

“…There is increasing focus on the occurrence of human pharmaceuticals in surface and wastewaters, and metformin is often at or near the top of the list with respect to the number of source detections and levels ( 40 ). Metformin has a moderate half-life of 5 to 10 days in river simulation studies, with variation related to microbial diversity ( 41 ).…”

Inclusion of Pesticide Transformation Products Is Key to Estimating Pesticide Exposures and Effects in Small U.S. Streams

“…Sublethal effects were explored using exposure-activity ratios (EAR) , based on the ToxCast database, which provides vertebrate-centric exposure-response metrics for more than 9000 organic chemicals to as many as 1100 molecular bioassay endpoints that include such groups as DNA binding and oxidoreductase . The approach is analogous to the comparison to screening-level benchmarks.…”

“…Detected concentrations were divided by the acute invertebrate or nonvascular plant benchmark to obtain a toxicity quotient (TQ) for that pesticide compound in that sample toward invertebrates or nonvascular plants. Sitespecific cumulative risk for pesticide mixtures under a maximum-exposure scenario was estimated as the sum of the maximum TQ measured for each compound at a site 63 using the toxEval version 1.1.1 package of the open source statistical software R. 63−65 Sublethal effects were explored using exposure-activity ratios (EAR) 66,67 based on the ToxCast database, which provides vertebrate-centric exposure-response metrics for more than 9000 organic chemicals to as many as 1100 molecular bioassay endpoints that include such groups as DNA binding and oxidoreductase. 66 The approach is analogous to the comparison to screening-level benchmarks.…”

Storm Event–Driven Occurrence and Transport of Dissolved and Sorbed Organic Micropollutants and Associated Effects in the Ammer River, Southwestern Germany

“…More and more anthropogenic organic compounds are being used in a broad range of applications and have become indispensable to our modern society. Because of high usage and consumption, they are regularly found in the aquatic environment (Casado et al 2019;Bradley et al 2020). Due to their use-specific properties, such as high persistence of flame retardants or effects of pesticides and pharmaceuticals on biological organisms (Daughton and Ternes 1999), they may pose a hazard to ecosystems and drinking water quality (Alpizar et al 2019; European Environment Agency 2019).…”