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Research on Methods for Water System Management to Minimize Human and Ecological Health Risk

Protection of our water resources is compromised by shortcomings in our abilities to adequately determine and reduce the full range of risks posed by waterborne contaminants, including chemicals and microbial pathogens.

EPA researchers are developing and evaluating effective tools to measure waterborne contaminants. These tools are essential for determining the risks these pollutants pose to people and the environment. With these tools, the source and level of contaminants can be evaluated, the risk posed to exposed communities can be characterized, and approaches for improving affected water resources can be developed.


Evaluation and Application of Improved Microbial Methods

Legionella on petri dishA key responsibility of the EPA under the Safe Drinking Water Act and the Clean Water Act is to develop methods to detect and quantitate waterborne contaminants, including microbes, that affect water systems. Recent efforts in method development and application have focused on opportunistic pathogens, such as Legionella and Mycobatcteria, which are of particular concern for drinking water systems. This work has provided more detail on the frequency and level of contamination of these microbes in commercial and residential water systems. In addition, methods for detecting several enteric viruses were used in a large virus occurrence study, and a comparison of staining kits used for detecting the protozoan pathogen Giardia in source water was conducted.

Advancements are also being made toward the development of rapid, nucleic acid based methods to detect somatic coliphages, which are alternative indicators of fecal pollution and an attractive surrogate for viral pathogens. These newer methods have the potential to provide evidence of fecal contamination in a matter of hours instead of days.

Recent Research Publications:

Development and Application of Chemical Methods and Optimization of a Distribution Management Tool

PFAS Methods DevelopmentDeveloping and using methods and models to measure chemical contaminants is a critical responsibility of the Agency. One recent area of focus has been the development and use of occurrence methods to detect several different classes of contaminants of emerging concern (CECs), including per- and polyfluoroalkyl substances (PFAS) and algal toxins. Collectively this work has helped characterize the level of chemical contamination across the Nation.


PFAS Methods:

Cyanotoxin Methods:

Technical Brief:

Recent Research Publications:

Health Effects Methods/Tools

Bioassay-sample tray and pipetteTools that enable EPA to measure the impact of contaminants on human health and the environment are essential for determining the risk posed by pollutants. Recent efforts have focused on the use of novel bioassays, such as those based on Adverse Outcome Pathways (AOPs) or metabolomic techniques, to assess the risk posed by various chemical pollutants. In addition, large scale studies aimed at determining the public health or environmental significance of chemical contaminants were done. This work has significantly improved our understanding of the health risks posed by chemical contaminants.

Technical Brief:

Table of Existing Bioassays:

Assay Description References
T47D-KBluc Human breast cancer cell line that naturally expresses estrogen receptors and has been engineered to stably express an estrogen responsive reporter gene (luciferase). Estrogenic compounds in a sample will bind estrogen receptors, dimerize and then bind to DNA and activate expression of the reporter gene. The reporter gene catalyzes a reaction that is measured in light units. The more potent the estrogen, the more light produced.
MDA-kb2 Similar to above, a human breast cancer cell line that naturally expresses androgen and glucocorticoid receptors and has been engineered to stably express a luciferase reporter gene. Compounds that bind either androgen or glucocorticoid receptors can activate the reporter gene. The use of an androgen receptor specific inhibitor can differentiate between AR and GR activity.
CV-1 transient GR assay Monkey kidney cells are transfected (infected) with two different Adenoviruses. One has the GR or AR gene and the other a reporter gene. Both genes are expressed. The chemical (water) turns binds the GR or AR gene product, which in turn, activates the reporter, which can produce light which can be measured. The more light, the more chemical in the water.
Steriodogenesis Pimephales promelas Water samples are used to prepare tissue culture medium. Ovary tissue from control fathead minnows are incubated in the medium for 12 hours and concentrations of 17b-estradiol (E2) and testosterone (T) excreted into the medium are measured by radio-immunoassay. The assay provides an indication of whether contaminants in the water sample are capable of inhibiting key enzymes or reactions involved in steroid hormone biosynthesis.
Gene expression Pimephales promelas The gene expression work complements the steroidogenesis assay above. Specifically, if significant effects on either E2 or T production are observed, real-time PCR will be used to determine if in vitro exposure to the water samples resulted in altered expression of genes coding for key, rate limiting, enzymes involved in steroid biosynthesis.
Nuclear receptor and transcription factor activation Extracts of selected water samples from the WW2DW project will be analyzed using the Attagene battery of Toxcast assays. Attagene employs a HepG2 cell line transfected with libraries of cis- and trans-regulated transcription factor reporter constructs to simultaneously evaluate approximately 80 different transcription factor activities.
Metabolite profiling Danio rerio Endogenous metabolites in zebrafish (Danio rerio) liver cells will be extracted and analyzed by nuclear magnetic resonance spectroscopy and mass spectrometry to determine biochemical pathways impacted by exposure to collected surface waters. Measured impacts on biochemical pathways will be used to determine the primary toxicity of the water samples.
RNA-seq This method employs next generation sequencing to provide a global picture of the levels of expression within exposed organisms (larval FHM). We are addressing additional questions regarding the consistency of the expression profile over time and sites (upstream and effluent) as well as grab sample vs. deployment.  
Mutagenicity Ames assay with and without metabolic activation The Ames mutagenicity assay allows the water samples collected and extracted in this study to be compared to the existing literature on the mutagenicity of water. For complex mixtures of water contaminants, the Ames assay provides the richest database to date.
Microtox assay The Microtox assay is a rapid screening assay for water samples that uses bioluminescent bacteria to detect toxicants in water. The assay has undergone verification by the Envrironmental Technlology Program.

Disclaimer: This  table has been provided for informational purposes only. Any mention of or reference to commercial products, processes, or services by trade name, trademark, manufacturer, or otherwise does not imply an endorsement by EPA.  EPA does not endorse any commercial products, services, or enterprises.

Recent Research Publications: