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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

Daphnia magna were exposed to the test substance in a static test conducted by Hüls AG (1995) according to EU method C.2. Five concentrations ranging from 5.2 to 73 mg/L were tested over a period of 48 hours. The EC50 (48 hours) was determined as 27 mg/L. A second freshwater test with Daphnia magna was conducted by Bayer AG (2000) with an EC50 of 35 mg/L.

Another study was conducted with the marine crustacean Chaetogammarus marinus (Adema 1982). The study was not well documented and was characterised by some deficiencies (e.g. no standard protocol, no analytical monitoring, etc.). The EC50 (96 hours) was determined as 4.0 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
27 mg/L
EC50/LC50 for marine water invertebrates:
4 mg/L

Additional information

Among the two valid freshwater studies, the highest sensitivity was observed in the test which was conducted by Hüls AG (1995) and therefore this test was determined as key study. The test conducted with the marine crustacean Chaetogammarus marinus (Adema 1982) was also determined as key study, although its reliability is limited by some restrictions: no standard protocol, no standard organism, no analytical monitoring, use of a solubilizer.

In view of the low solubility in water (see chapter 4.9) and the liability towards hydrolysis (see chapter 5.1.2) of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, exposure to well-defined aquatic concentrations is difficult to achieve. Due to fast hydrolysis, the observed effect is expected to be the effect of the hydrolysis product. In the aquatic environment, only the chemically less reactive hydrolysis product is expected to be relevant. The methods used for the determination of the test substance concentration (DOC or TOC) do not differentiate between parent substance and hydrolysis product. Hence the analytical results should be treated with caution.