The accumulation and depuration of bis(tributyltin) oxide (TBTO), a widely used active ingredient in antifouling paints, and its acute and chronic toxicity to sheepshead minnows (Cyprinodon variegatus) were determined. Equilibrium between the concentration of carbon-14-labeled-TBTO in seawater and in fish tissues was not reached after 58 days of exposure. The maximum observed bioconcentration factor in whole fish was ×2600. The maximum observed bioconcentration factors for the muscle, viscera, and remains were ×1810, ×4580, and ×2120, respectively. Sheepshead minnows depurated 52 percent of the 14C-TBTO within 7 days and 74 percent after 28 days. The 21-day median lethal concentration (LC50) for sheepshead minnows exposed to TBTO was 0.96 ppb. The only statistically significant effect observed in the life-cycle test was mortality of the F0 fish in the mean measured TBTO concentration of 4.8 ppb. There was an obvious concentration-response relationship in mortality of the F1 fish, although, no statistically significant differences in mortality were detected between the control and the TBTO-exposed treatments. The surviving F1 fish exhibited no signs of abnormal development, nor was growth decreased as a result of F0 exposure to TBTO concentrations <-1.0 ppb. Tissue samples from the life-cycle test, analyzed for total tin, confirmed the bioconcentration of TBTO, showed the accumulation to be concentration dependent, and indicated that the fish were actively metabolizing TBTO into its lower and less toxic alkyl moieties.

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Aquatic toxicity tests were undertaken to evaluate the environmental significance of hexamethylphosphoramide (HMPA), an industrial solvent which has been shown to be an animal carcinogen. Hexamethylphosphoramide's 48-h LC50 to Daphnia magna and 96-h LC50 to bluegill sunfish (Lepomis macrochirus) were 4220 mg/litre and 7420 mg/litre, respectively. In concentrations up to and including 5140 mg/litre, HMPA did not interfere with the normal development of Eastern oyster (Crassostrea virginica) embryos to the veliger stage. Both sheepshead minnows (Cyprinodon variegatus) and Eastern oysters developed concentrations of HMPA in their tissues rapidly from 0.5, 8.4, and 40.4 mg/litre treatments, with the plateau concentrations rarely exceeding the exposure concentrations. Whole-body residues peaked in about three to seven days after the initiation of exposure. Sheepshead minnows demonstrated a greater ability to metabolize HMPA than oysters, while oysters depurated HMPA and its metabolites more rapidly than fish. Both species largely eliminated HMPA and its metabolites within one day of depuration. The bioconcentration factors for fish and oysters were less than four, which suggests that HMPA does not pose a substantial environmental hazard from the standpoint of its accumulation in aquatic organisms. The oyster mortality in the 8.4 and 40.4 mg/litre treatments was appreciably greater than that in the controls, while the fish mortality was similar among all the treatments and the control.