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Pacific EcoRisk Environmental Consulting & Testing <br />2.3 Acute Toxicity Testing with Fathead Minnows <br />The fathead minnows used in these tests were obtained from a commercial supplier (Thomas <br />Fish Company, Anderson, CA). These fish were maintained at 20°C in aerated aquaria <br />containing EPA synthetic soft water prior to their use in these tests. <br />These hazardous waste evaluations were each run at sample concentrations of 250, 500, and 750 <br />mg/L, with a Lab Water Control consisting of the same synthetic EPA "soft" water. There were <br />two replicates at each test treatment, each replicate consisting of 9.2 L of media in a 10-L <br />container. Water quality characteristics (pH and dissolved oxygen [D.O.]) were determined for <br />the test solution in each test replicate prior to initiation of this test. <br />The tests were initiated with the random allocation of 10 juvenile fathead minnows into each <br />replicate container. These containers were placed in a temperature -controlled room at 20°C, <br />under fluorescent lighting on a 16L:8D photoperiod. <br />Each day, each replicate container was examined, and the number of live fish in each was <br />recorded. Routine water quality characteristics (temperature, pH, and D.O.) of the treatment <br />waters were measured and recorded for each replicate container each day. <br />After 96 (±2) hrs, the tests were terminated and the number of live fish in each replicate <br />container was determined. The fish in a randomly selected Lab Control treatment replicate were <br />then euthanized and measured for total length (to the nearest 0.1 mm) and weighed (to the <br />nearest 0.001 g). The resulting survival data for the waste treatments were evaluated to determine <br />the LC50 using the CETIS® statistical software (TidePool Scientific, McKinleyville, CA). <br />Page 2 1(� J <br />5/21 <br />