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t t <br />Y <br />In non-passeriform birds, the acute toxicity (LD50) of toxaphene to nine <br />species tested ranged from a low of 14.1 mg/kg (extremely toxic) for the <br />sharp-tailed grouse to a high of 316 mg/kg (moderately toxic) for the <br />sandhill crane. The only passeriform species tested was the horned lark, <br />with an LD50 of 581 mg/kg (moderately toxic) (Hudson et al., 1984). <br />Experimental studies of the white leghorn chicken, ring-necked pheasant, and <br />bobwhite quail revealed alterations in growth and reproduction after sublethal <br />dietary exposures to toxaphene. In black ducks, up to 50 parts per million <br />(ppm = mg/kg) did not alter egg production or hatchability, but duckling <br />growth was decreased significantly for about 14 days after hatching. This <br />growth decrease was delayed in ducklings fed 10 ppm. Toxaphene also affected <br />backbone development at 10 and 50 ppm, and it has been suggested that skin and <br />connective tissue might also be affected, reducing the wound healing ability <br />of the skin (Mehrle et al., 1979). <br />In mammals, the LD50 ranged from 139 mg/kg to 240 mg/kg (highly toxic) for <br />mule deer and greater than 160 mg/kg (highly toxic) for the domestic goat <br />(Hudson et al., 1984). In rats, half of the toxaphene administered as single <br />oral doses was eliminated in 1 to 3 days (EPA, 1980). <br />Sampling of aquatic systems has consistently shown greater average levels of <br />organochlorine contamination than terrestrial systems (Keith and Hunt, 1966). <br />Toxaphene presents a greater hazard to aquatic life because it is persistent <br />and readily accumulated by invertebrates, fish, and plants.. Toxaphene is 1/10 <br />as toxic to fish as endrin, 3 times as toxic as dieldrin, and 5 times as toxic <br />as DDT. <br />Toxaphene at low concentrations (low parts per billion) is acutely toxic to <br />fish and lower concentrations (parts per trillion) will kill fish after long- <br />term exposure. The 96-hour LC50 for toxaphene exposure to the channel catfish <br />is about 13.1 ug/1 (extremely toxic): for the black bullhead about 3.7 ug/1 <br />(super toxic) (Johnson and Finley, 1980). The time independent LC50 for <br />channel catfish, the only species of interest for which we have this figure, <br />is 1.0 ug/1. : <br />In a study by Mehrle and Mayer (1977), low levels of toxaphene in water did <br />not affect growth and spawning activity of adult channel catfish or egg <br />hatchability. However, within 30 days after hatching, toxaphene concentra- <br />tions of 224 and 535 ng/1 had caused significant fry mortality and decreased <br />growth. Channel catfish fry accumulated toxaphene more rapidly than adults. <br />The channel catfish "no effect" water concentration of toxaphene on growth was <br />between 129 and 299 ng/1; and between 47 and 72 ng/l for bone composition. <br />Toxaphene is rapidly absorbed by fish from surrounding water and stored in <br />fat. When a contaminated fish is transferred to clean water, toxaphene is <br />released very slowly. Catfish can retain 90% of the stored toxaphene for more <br />than a month. In blue catfish (Ictalurus furcatus), filets contained 50% of <br />the whole body toxaphene residue concentration (Fite et al., 1983). The <br />difference between filet and whole body residues may differ by more than a <br />factor of 10 in some species (Jim Zigchek, CNFRL, personal communication). <br />Although both routes of exposure can account for significant residue <br />accumulation, most organochlorine residues accumulated by higher order <br />3