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Diss Factsheets

Ecotoxicological information

Long-term toxicity to fish

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fish early-life stage toxicity
Data waiving:
study scientifically not necessary / other information available
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Testing for long-term toxicity to fish is not considered necessary because:
- Short-term toxicity to fish is low.
- The risk characterisation ratios (RCR) based on PNECfreshwater derived from the acute data are <1.

Description of key information

Key value for chemical safety assessment

Additional information

No long-term toxicity to fish data are available for the registered substance, which moderately rapidly hydrolyses to (3-chloropropyl)silanetriol and ethanol (half-life: 35 hours at 25°C and pH 7). Chemical safety assessment and PNECs are based on the parent substance and the silanol hydrolysis product.


Measured short-term aquatic toxicity data are available for the registered substance, (3-chloropropyl)triethoxysilane, in which, test organisms were exposed to a mixture of parent substance and hydrolysis products. These data are currently used to derive PNECs for the parent assessment entity.


Short-term tests conducted with fish and algae (according to OECD 203 and 201, respectively) are ongoing with the registered substance. These tests are designed to maximise the exposure of the test organisms to the parent substance. Once the results of these studies have become available, long-term aquatic testing with the most sensitive trophic level (either Daphnia or fish) will be proposed with the parent substance. The tests will be conducted to fulfil the data requirements for the parent substance.


Long-term toxicity testing with fish is therefore not currently required, until the results of the short-term studies with fish and algae are available.


In addition, based on the current short-term aquatic data set for the parent substance, the most sensitive trophic level is invertebrates, where some toxicity was observed below 100 mg/l (Daphnia 48-hour EC50 21.2 mg/l). A PNEC has been derived for the purpose of chemical safety assessment using the invertebrate 48-hour EC50 value of 21.2 mg/l as the starting point. An assessment factor of 1000 was applied to derive the freshwater PNEC. Using this PNEC, Risk Characterisation Ratios (RCRs) are below 1. For a narcotic chemical without a specific mode of toxic action, it is unlikely that the aquatic PNEC would be significantly over-estimated using this method.


Based on the highest freshwater RCR available for the parent substance, (3-chloropropyl)triethoxysilane (0.627 mg/l) with a corresponding Predicted Environmental Concentration (PEC) of 0.013 mg/l, the PNECaquatic (freshwater) value would need to be =0.013 mg/l to result in RCR values =1. This value is 1.63 times lower than the current PNECaquatic (freshwater), based on the short-term dataset (0.0212 mg/l). A PNECaquatic (freshwater) value of =0.013 mg/l would correspond to a long-term EC10 or NOEC value of =0.65 mg/l when applying an assessment factor of 50, indicating high toxicity which was not observed in the existing short-term dataset.


Overall, until the results of the new studies become available, it is concluded that the risk characterisation conclusion is sufficiently conservative.


Details on how the PNECs and the risk characterisation ratios have been derived can be found in IUCLID Section 6.0, CSR Section 7.0, and Chapters 9 and 10 of the Chemical Safety Report, respectively.