Bioanalytical cell screening assays are a commercial technology initially used by the pharmaceutical and food-safety industry that is being adapted to screen for biologically active contaminants in aquatic systems. Many of the bioactive contaminants that can be screened with cell assays are not being routinely monitored in aquatic systems, despite strong evidence of their ubiquity and potential to trigger adverse biological impacts in fish and other animals, including interfering with metabolic functions, reproduction and tissue integrity.
SCCWRP is part of an international group of researchers working to adapt commercially available cell assays to serve as a cost-effective, reliable method for rapidly screening water bodies and inferring potential toxicity. A key focus of this research is characterizing the relationship, or linkage, between how a cell assay responds to a given level of contamination, and how fish and other animals would respond in the environment to this same level of contamination. SCCWRP’s long-term goal is to use cell assays to identify and prioritize water bodies for more extensive chemical and/or toxicity monitoring.
Next-generation monitoring strategy
Aquatic systems contain tens of thousands of emerging contaminants, from personal care products to pharmaceutical compounds to disinfection byproducts. The vast majority of these chemicals go undetected through traditional monitoring methods, and their health risks are poorly understood. Bioanalytical cell screening assays are at the center of a proposed next-generation management strategy to significantly expand the universe of bioactive chemicals that can be routinely monitored.
Cell assays consist of high-throughput cell lines that react in predictable ways to chemical exposure, enabling researchers to gain insights into the biological modes of action by which emerging contaminants can impact animal and human health. California’s water-quality management community has begun using cell assay technology to rapidly zero in on which types of chemicals pose a potential threat. Under a risk-based monitoring framework that has been proposed by SCCWRP and its partners, water-quality managers would complete rapid, cost-effective water body screenings first, then deploy more labor-intensive, tailored technologies to follow up on the screening’s findings.
Interpreting cell assay results
SCCWRP and its partners have spent more than a decade studying the potential of cell assay technology to monitor emerging contaminants in aquatic systems. This work involves developing and standardizing laboratory protocols for a suite of cell assays responsive to particular classes of bioactive chemicals, such as estrogen and aryl hydrocarbon receptors. SCCWRP and its partners also are working to characterize the linkage between cell assay responses in a laboratory and biological impacts to aquatic organisms in the field. Researchers’ goal is to show that cell assays can reliably detect cellular-level responses that would ultimately manifest as tissue damage and other impacts in living organisms; these impacts occur through a predictable sequence of biological events known as an adverse outcome pathway.
The linkage studies will pave the way for developing quantitative bioscreening thresholds that define when a water body should undergo additional testing. These additional tests, including whole-organism toxicity testing and targeted chemical analysis, are part of a multi-tiered emerging contaminants monitoring framework proposed by SCCWRP to more comprehensively monitor bioactive contaminants in aquatic systems.