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Long-term toxicity to fish

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Reference
Endpoint:
fish early-life stage toxicity
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
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data waiving: supporting information
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Description of key information

Key value for chemical safety assessment

Additional information

Due to the very rapid hydrolysis of the substance, the chemical safely assessment is based on the silanol hydrolysis product vinylsilanetriol (CAS 143-48-6).

 

In accordance with Column 2 of REACH Annex IX, there is no need to further investigate the effects of this substance in a long-term aquatic toxicity to fish study because, as indicated in guidance R.7.8.4.3 (ECHA 2016), the quantitative chemical safety assessment (conducted according to Annex I of REACH) indicates that the Risk Characterisation Ratio is well below 1, and therefore the risk is already adequately controlled and further testing is not justifiable.

 

The substance is highly water-soluble and has low potential for bioaccumulation (based on log Kow <3 (-2.0)) and there is no reason to expect any specific mechanism of toxicity beyond narcosis. Therefore, the occurrence of toxic effects below 100 mg/L that were not expressed in the existing short-term aquatic studies would be considered unlikely.

 

Based on the short-term aquatic data set, toxicity to fish is low; the most sensitive trophic level is Daphnia and a long-term Daphnia reproduction test is available.

 

A PNEC has been derived for the purpose of chemical safety assessment. An assessment factor of 50 was applied to derive the freshwater PNEC using the long-term Daphnia result. The availability of the long-term result covering the most sensitive species in the aquatic tests, and the application of an appropriate assessment factor, means it is, therefore, unlikely that the aquatic PNEC would be significantly over-estimated.

Based on the exposure assessment of the registered substance, the highest PEC/PNEC for vinylsilanetriol is 0.362/0.4 = RCR 0.904. If a long-term toxicity to fish test were to be conducted, an assessment factor of 10 would be applied to the results of the lowest long-term effect concentration to derive PNECaquatic (based on the availability of three long-term toxicity values from three trophic levels). The fish would have to exhibit a dose response of <4 mg/l to be more conservative than the current PNECaquatic of 0.4 mg/l derived from the chronic invertebrate data. There is no basis to expect such toxicity for vinylsilanetriol based on the absence of significant short-term toxicity observed in aquatic tests, the fact that fish were the least sensitive trophic level in the short-term aquatic tests and the low potential for bioaccumulation of vinylsilanetriol.

 

Overall it is concluded that the risk characterisation conclusion is sufficiently conservative in respect of any uncertainties and therefore further in vivo testing is not considered necessary or justified on ethical grounds.

 

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

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