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Long-term toxicity to fish

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fish early-life stage toxicity
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study scientifically not necessary / other information available
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Description of key information

Key value for chemical safety assessment

Additional information

Due to the rapid hydrolysis of the substance, the chemical safely assessment is based on the silanol hydrolysis products, divided in to three groups, Silanols HP X, Y and Z.


Testing for long-term toxicity to fish is not considered necessary because:


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. (ECHA 2016), the quantitative chemical safety assessment (conducted according to Annex I of REACH) indicates that further testing is not justified for the following reasons:  


The substance has acute toxicity data available for three trophic levels for each silanol assessment entity, as well as chronic invertebrate and algal toxicity data for silanol assessment entities HP-X and HP-Z.


For Silanol HP-X there were no effects observed at the highest concentrations tested, even when the substance was tested at high nominal concentrations of 500 mg/l.


For Silanol HP-Z, based on the available aquatic data the most sensitive trophic level in the short-term tests was invertebrates, but the most sensitive trophic level in the long-term tests was for algae.  Furthermore, no effects were observed in the short-term toxicity to fish test even when the substance was tested at high nominal concentrations approaching 1000 mg/l.


For Silanols HP-X and HP-Z, no PNECs have been derived because no hazard is identified.


For Silanol HP-Y, short-term toxicity of the test substance and degradation products to fish is low and the most sensitive species was algae. An assessment factor of 1000 was applied to derive the freshwater PNEC, this high assessment factor to derive the predicted no-effect level already reflects the typically higher value of a short-term EC50 compared to a long-term EC10. 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.


The PNEC has been derived for the purpose of chemical safety assessment and the risk characterisation ratios for Silanol HP-Y are below 1.


Silanol HPs X and Z are highly water-soluble and have low bioavailability based on log Kow <3.


Overall it is concluded that the risk is adequately assessed using the short-term data and the long-term invertebrate tests, and that in vivo testing on vertebrate animals 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.