Abstract |
Acute (96-h) flow-through toxicity tests with endosulfan (Thiodan) were conducted with several estuarine animals. The test species and their 96-h lethal concentration for 50 percent of the organisms (LC50) values were: pink shrimp (Penaeus duorarum), 0.04 micrograms/litre; grass shrimp (Palaemonetes pugio), 1.3 micrograms/litre; pinfish (Lagodon rhomboides), 0.3 micrograms/litre; spot (Leiostomus xanthurus), 0.09 micrograms/litre; and striped mullet (Mugil cephalus), 0.38 micrograms/litre. In a 56-day bioconcentration study (28-day uptake, 28-day depuration), striped mullet were exposed to 0.008 and 0.08 micrograms endosulfan/litre seawater. The two endosulfan isomers (endosulfan I and II) were rapidly metabolized to endosulfan sulfate; only trace amounts of each isomer were detected in edible tissue or offal of mullet exposed to 0.08 micrograms/litre (0.035 micrograms/litre measured) for 28 days. Maximum bioconcentration factors of endosulfan were 2249 in edible tissue and 2755 in whole-body analyses. After 48 h in pesticide-free seawater, endosulfan was not detected in the previously exposed mullet. The authors studies suggest that endosulfan in the estuarine environment would be a hazard because of its acute toxicity and bioconcentration potential, but animals surviving exposure and moving to areas free of endosulfan would lose the chemical rapidly. (Copyright (c) American Society for Testing and Materials, 1977.) |