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Untargeted MS-based Monitoring of Glucuronides in Fish: Screening Complex Contaminant Mixtures for Biological Relevance (2020 MANA Conference)
Citation:
Mosley, J., M. Evich, I. Ntai, J. Cavallin, Dan Villeneuve, G. Ankley, AND Tim Collette. Untargeted MS-based Monitoring of Glucuronides in Fish: Screening Complex Contaminant Mixtures for Biological Relevance (2020 MANA Conference). 2nd Annual Metabolomics Association of North America (MANA) Conference, Virtual, September 14 - 16, 2020.
Impact/Purpose:
Environmental authorities increasingly detect contaminants of emerging concern (CEC) in surface waters. However, the toxicological data required to inform decision making can be lacking, particularly for complex mixtures of contaminants. This makes it difficult for managers to assess which CECs pose risks, the types of effects to expect, and how to prioritize, monitor, and manage relevant risks. High throughput effects-based monitoring approaches, such as metabolomics, show considerable potential for informing ecological risk assessments, in part, by identifying biological activity present at environmental sites which contain complex mixtures of contaminants. Thus, it is logical that an initial screen to prioritize contaminants in complex mixtures be based on bioavailability. To this end, we pursued an untargeted metabolomics-based approach to prioritize CECs in WLSSD treated wastewater effluent, which discharges into the St. Louis River, Duluth, MN, which is an Area of Concern within the Great Lakes Restoration Initiative. This biologically based approach first focused on glucuronidation, which is a major metabolic pathway of detoxification, and thus an important indicator of bioavailability. We analyzed xenobiotic glucuronides present in gallbladders of fish exposed to WLSSD effluent to identify bioavailable contaminants from environmental mixtures, resulting in the tentative identification of over 100 glucuronides, corresponding to more than 60 chemical contaminants. Importantly, the majority of these chemical contaminants are not currently targets of routine chemical monitoring. These results can be used both to prioritize current chemical contaminant lists and to identify novel chemical contaminants that may be responsible for adverse outcomes identified via effects-based monitoring. These findings can be of particular interest to chemical monitoring entities, waste-water treatment managers and the general public.
Description:
The increasing complexity of contaminant mixtures in surface waters has made traditional assessments of risk to human health and the environment progressively more difficult, requiring new and advanced, novel analytical approaches. For example, methods are needed to identify contaminants for which routine chemical analyses are not performed, in addition to prioritizing both detected and undetected chemicals by both biological and toxicological relevance. Tracking biotransformation products of chemical contaminants in an untargeted fashion facilitates the identification of xenobiotics taken up by the resident environmental species (e.g., fish), and can inform risk based on known detoxification pathways. As a first step, we investigated xenobiotic glucuronidation, which is generally accepted as the most biologically relevant phase II metabolic pathway for pharmaceuticals, pesticides, and other environmental contaminants frequently encountered by organisms in the environment. Glucuronidation consists of the attachment of a glucuronic acid moiety to the xenobiotic (or to its phase I metabolite(s)) to aid excretion and thus, we developed a novel untargeted mass spectrometry-based method for identifying these glucuronides in tissues and biofluids in aquatic species. The application of this method to gallbladders from fish exposed to wastewater treatment plant effluent revealed the presence of over 70 biologically relevant xenobiotic-glucuronides, the majority of which were not targets of conventional contaminant monitoring. These results highlight the need for developing novel, biologically based untargeted screening methods for evaluating chemical contaminants in complex environmental mixtures to aid in both human and ecological risk assessment.
