Octamethylcyclotetrasiloxane in aquatic sediments: Toxicity and risk assessment

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 c...

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Bibliographic Details
Published in:Ecotoxicology and environmental safety 1994-12, Vol.29 (3), p.372-389
Main Authors: Kent, David J., McNamara, Pauline C., Putt, Arthur E., Hobson, James F., Silberhorn, Eric M.
Format: Article
Language:English
Subjects:
Animal, plant and microbial ecology
Animals
Applied ecology
Biological and medical sciences
Carbon Radioisotopes
Chironomidae
Chironomidae - physiology
Chironomus tentans
Diptera
Dose-Response Relationship, Drug
Ecosystem
Ecotoxicology, biological effects of pollution
Fresh Water
Fresh water environment
Freshwater
Fundamental and applied biological sciences. Psychology
Larva - physiology
Risk Assessment
Siloxanes - toxicity
Soil
Time Factors
Water Pollutants - toxicity
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Summary: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 μg/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.
ISSN:0147-6513
1090-2414
DOI:10.1016/0147-6513(94)90010-8