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Selection of a Battery of Rapid Toxicity Sensors for Drinking Water Evaluation
ARMY CENTER FOR ENVIRONMENTAL HEALTH RESEARCH FORT DETRICK MD
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Comprehensive identification of chemical contaminants in Army field water supplies can be a lengthy process, but rapid analytical methods suitable for field use are limited. A complementary approach is to directly measure toxicity instead of individual chemical constituents. Ten toxicity sensors utilizing enzymes, bacteria, or vertebrate cells were tested to determine the minimum number of sensors that could rapidly identify toxicity in water samples containing one of 12 industrial chemicals. The ideal sensor would respond at a concentration just exceeding the Military Exposure Guideline MEG level for the chemical an estimated threshold for adverse effects but below the human lethal concentration. Chemical solutions were provided to testing laboratories as blind samples. No sensors responded to deionized water blanks, and only one sensor responded to a hard water blank. No single toxicity sensor responded to more than six chemicals in the desired response range, and one chemical nicotine was not detected by any sensor with the desired sensitivity. A combination of three sensors Microtox, the Electric Cell Substrate Impedance Sensing ECIS test, and the Hepatocyte low density lipoprotein LDL uptake test responded appropriately to nine of twelve chemicals. Adding a fourth sensor neuronal microelectrode array to the test battery allowed detection of two additional chemicals aldicarb and methamidophos, but the neuronal microelectrode array was overly sensitive to paraquat. Evaluating sensor performance using a standard set of chemicals and a desired sensitivity range provides a basis both for selecting among available toxicity sensors and for evaluating emerging sensor technologies. Recommendations for future toxicity sensor evaluations are discussed.
APPROVED FOR PUBLIC RELEASE