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Microbiological and Chemical Exposure Assessment


Exposure to certain kinds of bacteria, molds, viruses, and single-celled organisms can lead to health risks for human beings. EPA microbiologists study how these organisms and pathogens spread in areas where people live, work, and play—and how we can limit our exposures to the types that can be hazardous to our health. EPA scientists have developed methods for detecting, characterizing and measuring bacteria, viruses and protozoa in drinking water, ground water and recreational water. DNA and immuno-based methods, as well traditional cultural methods, are used to measure hazardous bacteria, viruses, fungi and protozoa. Analytical quantitative methods are developed to measure human risk factors associated with inhalation, ingestion and dermal pathways.

Research Projects

Using mussels to detect microbial contamination of ambient water
Mussels and other bivalves are very efficient natural filtration devices that can filter up to 5 liters of water per hour to feed on microscopic plants and nutrients in water. EPA scientists are taking advantage of this ability by developing a low cost and effective concentration method using native and invasive species, like Blue mussels and Asian clams to collect an array of microbial pathogens from water.

Using propidium monoazide for detecting viable microorganisms
Molecular methods that detect nucleic acids are increasingly being used to identify microbial contaminants in the environment. EPA scientists are conducting several projects designed to test the efficacy of propidium monoazide (PMA)  a nucleic acid intercalating dye that does not penetrate the membranes of live cells or the capsids of intact viruses.

Sample preparation techniques for concentrating microbes from water
Methods for detecting low concentrations of microorganisms in the environment are needed to understand the risk posed by waterborne pathogens. EPA scientists are investigating several alternative approaches for concentrating microbes from water more effectively and increasing the range of microbes that can be isolated simultaneously. This work has resulted in the identification of low cost alternative sample concentration techniques.

Developing methods to detect viruses in water
Viruses, such as enteroviruses and noroviruses, can spread in groundwater systems but are difficult to detect. EPA scientists have developed a way to quickly screen water for these contaminants.

Saliva-based measurement method for detecting exposure to waterborne pathogens
Exposure scientists at EPA have developed a quick, inexpensive method to sample swimmers’ saliva to understand links between exposure to pathogens in water and human health. Using swabs of saliva, which can be collected quickly and non-invasively, scientists can look for specific antibodies created by the immune system in response to exposure to certain microbes.

Developing and validating same-day method for monitoring recreational waters
Traditional methods of recreational water testing require at least 24 hours for results, which means beach managers may not know to issue swimming advisories until after a bacterial outbreak. A new method developed by EPA scientists cuts the laboratory testing time down to just four hours.

Understanding risks from pathogens in piped water systems
Legionella bacteria can grow in piped water systems and lead to respiratory infections in humans. EPA scientists are studying how these bacteria spread in plumbing systems, and how to reduce human exposure to them.

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