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<br />C> <br />l""':'') <br />1') <br />,::. <br />1-- <br />f.) <br /> <br />1984). Stock solutions of selenium were prepared in deionized water using sodium selenate <br /> <br />(Na2Se04) obtained from Johnson Matthey (Ward Hill, MA) and sodium selenite (Na2SeOJ) <br /> <br />obtained from Aldrich Chemical (Milwaukee, WI) at a 6: I ratio of selenate:selenite. The <br /> <br />selenium stock solution was delivered to the diluter system by automated pipettes (Micromedic <br /> <br />Systems, Horsham, PAl. <br /> <br />To document exposure concentrations during the adult study, 100 ml of water were <br /> <br />collected from all exposure tanks on days 0, 15, 75, 120, 149, 166, and 180 of the study and from <br /> <br />one replicate of each treatment on days 215 and 245 of the study for analysis of total selenium. <br /> <br />Water samples were collected in 125-ml acid-cleaned plastic bottles, preserved in 1% <br /> <br />instra-anaJyzed Hel (JT Baker, Phillipsburg, NJ), and frozen until analysis, <br /> <br />The selenium-fortified diets were introduced on the day after the selenium-spiked water <br /> <br />was introduced and this dietary exposure was considered as day I of the study. Daily rations of <br /> <br />test diets were adjusted periodically during the early part of the study to minimize the amount of <br /> <br />uneaten food in the tanks. Fish were fed at a rate (based on total weight of fish in each tank) of <br /> <br />1.1 % for days 1-23, L7-2.0% for days 24-40, 1.5% for days 41-60, L75% for days 61-90, and <br /> <br />2.0% for days 91-245 of the study. Fish were fed three times a day during the first 2 weeks and <br /> <br />five times a day thereafter. Food was withheld on days when growth was measured, <br /> <br />On the day the waterborne exposure began and every 30 days thereafter, all fish were <br /> <br />identified from the PIT tag, weighed (nearest g, A&D model HW-IOKA2 scale, A&D <br /> <br />Engineering, Milpitas, CA), measured for total length (nearest mm), and examined for general <br /> <br />health, Also, a muscle plug was taken from each female for selenium residue analysis at these <br /> <br />sampling intervals. The plugs, which include the skin and scales, were taken from the <br /> <br />mid-dorsal area about 1-2 cm below the dorsal fin, using a sterile 5-mm biopsy punch (Miltex <br /> <br />10 <br />