Chemical and microbial contaminant grouping for evaluating ecological and human health
This task will investigate the occurrence of multiple analytes (both chemical and microbial) in water matrices (potentially wastewater, surface water, ground water, and drinking water) and determine the ecological and human health effects that result from exposure to these contaminants.
Rationale and Research Approach:
To date, water quality research and regulatory actions generally have been compartmentalized with respect to stressors (specific chemicals, chemical groups, micro-organisms), receptor organisms (humans, aquatic life, wildlife), media (surface water, ground water, drinking water, waste water), and/or regulatory components (risk characterization, risk management, risk reduction). In most cases, this has been justified because regulatory actions did not require, or were little affected by, consideration of interactions between these elements, or because research was needed only for key uncertainties of regulatory frameworks. However, such compartmentalization can limit consideration of where and when interactions among different elements would be important to water quality management. As demand for water resources increases, wastewater and drinking water sources will become even more closely linked and the natural processes that reduce contaminant levels more burdened, requiring a better understanding of implications of these interactions to human and aquatic ecosystem health.
This task will seek to advance approaches to better integrate elements of water quality assessment and management, while continuing to address needs focused on specific stressors, receptors, and media. For clarity, this work is divided into five subtasks, with associated products. The first four subtasks involve focused research on products requested by the Office of Water (OW). These products will contribute to integrated assessments, but their priorities and boundaries are driven by immediate needs. The fifth subtask will utilize the unique mix of personnel and infrastructure present in ORD to integrate assessment tools across the water cycle and facilitate robust assessment and management of waterborne contaminants. Based on discussions across disciplines, this task will identify areas where more integrated and holistic research is needed and feasible, and will initiate such efforts.
In previous work, ORD scientists developed statistical methods for estimating the uncertainty associated with predicting aquatic life criteria (ALC) values from limited sets of toxicity data, and these methods were then incorporated into a method for deriving criteria-like guidance values. While useful, this approach frequently created substantial conservatism because of the uncertainties arising from having only limited data, and from having an approach that did not consider information beyond broad empirical relationships. At MED, as part of sub-task 4, new analyses will be undertaken to consider how other types of toxicological information, such as knowledge of chemical-specific toxicity pathways and computational, “omic,” or in vitro toxicological data could be used to better inform the extrapolation methods used to estimate benchmarks from limited data, and to streamline the development of interim regulatory guidance for chemicals without existing ALC. Research in this effort will be in collaboration with toxicologists in the CSS plan developing in-silico/in-vitro screening and prioritization tools to maximize their utility for eventual use in organism level regulatory development of “benchmarks” for various EPA program offices.
An important step in an AOP is route of exposure. Understanding the pertinent toxicological route of exposure will help define the anatomical location of the critical initiating events. Existing guidelines for ALC derivation focus solely on waterborne exposure, without consideration for simultaneous exposure through the diet and/or sediment. However, for many chemicals, substantial exposures occur through these other routes and are, in some cases, the primary determinant of toxic effects. ORD research in the past has centered on the effects of dietary metals on fish. While substantial progress has been made with regard to fish, studies in other laboratories have continued to suggest that adverse effects on aquatic invertebrates can occur because of dietary exposure to metals at waterborne concentrations well below existing criteria. While clearly of concern to criteria, understanding of this mechanism is far from sufficient to incorporate this pathway into the ALC derivation process. Research in this portion of the subtask will be focused on understanding the mechanisms underlying these effects on sensitive invertebrates, with the goal of determining how this pathway can be incorporated into ALC in a way that accurately reflects the combined risk of simultaneous exposure from multiple pathways.
Finally, for these concepts to be useful, they will need to be put into practice within the Program Offices. Namely, the Office of Water and the Office of Pesticides seek assistance on the use of the tools for harmonization of the program's separate assessment techniques and endangered species assessments.
Janz, D.M., D.K. DeForest, M.L. Brooks, P.M. Chapman, G. Gilron, D.J. Hoff, W.A. Hopkins, D.O. McIntyre, C.A. Mebane, V.P. Palace, J.P. Skorupa, and M. Wayland. 2010. Chapter 6: Selenium toxicity to aquatic organisms. Ecological Assessment of Selenium in the Aquatic Environment, SETAC Pellston Workshop, February 22–28, 2009, Pensacola, FL; P.M. Chapman, W.J. Adams, M.L. Brooks, et al., Eds.; CRC Press, Taylor and Francis, Boca Raton, FL, pp. 141-231.
|September 30, 2016||2.2.A.11 Develop methods to integrate exposure from multiple pathways in the context of aquatic life criteria and related assessments||Russell Erickson|
|September 30, 2015||2.2.A.9 Expanded approaches for developing aquatic benchmarks for chemicals with limited ecotoxicity data, to include bifenthrin/pyrethroids and selected pharmaceutical chemicals.||Russell Erickson|