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Microbiological and Chemical Exposure Assessment

Research In Action

Development and evaluation of large volume sample preparation techniques for microbial detection

Issue

Methods for detecting low concentrations of microorganisms in the environment are needed to understand the risk posed by waterborne pathogens. Therefore, effective, low cost techniques to concentrate and purify microbes from large volumes of water are critical. For example, viruses and parasites must often be isolated from 10-1600 liters of source water to be detected. Current sample collection techniques often require expensive filters, such as the Virosorb 1MDS filter, which have only been evaluated with a limited range of microbes.

Action

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. For instance, hollow-fiber ultrafiltration, which concentrates microbes by size, is being evaluated for both viruses and parasites, while the low-cost NanoCeram filter, which is based on charge interactions, is being evaluated for viruses. Scientists are also investigating an EPA developed technique that uses celite (diatomaceous earth) as a way to further concentrate and purify viruses from smaller volumes (30 milliliters -1 liter) of source water.

Result and Impact

This work has resulted in the identification of low cost alternative sample concentration techniques. In the long term, techniques such as hollow-fiber ultrafiltration are expected to be used in conjunction with multipathogen detection devices, opening the door to a multipathogen occurrence method. Such a method would be valuable for many applications, including large scale occurrence studies such as the one supporting the Unregulated Contaminant Monitoring Rule.

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