1. Octamethylcyclotetrasiloxane in aquatic sediments: toxicity and risk assessment.
- Author
-
Kent DJ, McNamara PC, Putt AE, Hobson JF, and Silberhorn EM
- Subjects
- Animals, Carbon Radioisotopes, Dose-Response Relationship, Drug, Ecosystem, Fresh Water, Larva physiology, Risk Assessment, Soil, Time Factors, Chironomidae physiology, Siloxanes toxicity, Water Pollutants toxicity
- Abstract
The toxicity of octamethylcyclotetrasiloxane (OMCTS) to the midge Chironomus tentans was examined in a series of aqueous and sediment exposures. Midge larvae were exposed for 14 days to five concentrations of radiolabeled [14C]OMCTS in each of three sediments (low, medium, and high organic carbon content). Additional tests were conducted with a water-only exposure. Results indicate the lowest 14-day no observed effect concentrations (NOEC) to be 65, 120, and 54 mg/kg for the low, medium, and high organic carbon sediments, respectively. For the water-only exposure, the 14-day NOEC was > 15 micrograms/liter. These results were used in the preparation of a risk assessment for OMCTS which took into consideration the physicochemical and environmental fate properties of the compound, as well as actual field monitoring and worst-case modeling results for assessment of exposure. Available evidence suggests that sediment concentrations of OMCTS do not present a risk to sediment-associated organisms. For 95% of sediment samples, data indicate that the margins of safety would be greater than 400 and potentially over 1000. Worst-case margins of safety were greater than 150.
- Published
- 1994
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