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Diss Factsheets

Ecotoxicological information

Long-term toxicity to fish

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Link to relevant study record(s)

fish early-life stage toxicity
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
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reference to other study
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reference to other study
Reason / purpose for cross-reference:
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Reason / purpose for cross-reference:
reference to other study

Description of key information

Key value for chemical safety assessment

Additional information

No data are available for the registered substance, which rapidly hydrolyses to N-(3-(trihydroxysilyl)propyl)ethylenediamine and methanol (half-life: 0.025 hours at 25°C and pH 7). Measured short- and long-term aquatic toxicity data are available for the parent substance, N-(3-(trimethoxysilyl)propyl)ethylenediamine, which are used to derive PNECs for the silanol hydrolysis product assessment entity. A long-term toxicity to fish test for N-(3-(trihydroxysilyl)propyl)ethylenediamine is not required for the following reasons:


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 the Risk Characterisation Ratio is below 1 and therefore the risk is already adequately controlled and further testing is not justifiable.


The substance is very water-soluble, has a low potential for bioaccumulation (based on log Kow <3 (-4.0)), especially in pH neutral conditions and there is no reason to expect any specific mechanism of toxicity beyond narcosis. Therefore, the occurrence of toxic effects that were not expressed in the existing short-term aquatic studies (conducted at concentrations up to 1000 mg/l with the registration substance (CAS 1760-24-3, EC 217-164-6)) would be considered unlikely. Additionally, evidence from data available within the analogue group of amine substances suggests that fish are the least sensitive trophic level. Furthermore, effects observed in the short-term toxicity to fish test conducted with the registration substance occurred at concentrations well above 100 mg/l, also demonstrating low sensitivity of fish.


Based on the short- and long-term aquatic data set for the parent substance, toxicity was observed below 100 mg/l. The most sensitive trophic level is algae, with a 72-hour ErC50 value of 7.2 mg/l and NOErC value of 2.5 mg/l. A PNEC has been derived for the purpose of chemical safety assessment using the algal 72-hour NOErC value of 2.5 mg/l as the starting point. An assessment factor of 50 was applied to derive the freshwater PNEC. 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.


A hypothetical analysis using the existing environmental exposure assessment has been carried out to determine what the results of a long-term aquatic study (as NOEC or EC10) would need to be to result in RCR values ≥1. Based on the highest freshwater RCR available for the silanol hydrolysis product, N-(3-(trihydroxysilyl)propyl)ethylenediamine (0.868) with a corresponding Predicted Environmental Concentration (PEC) of 0.043 mg/l, the theoretical PNECaquatic (freshwater) value would need to be ≤0.043 mg/l to result in RCR values ≥1. A PNECaquatic (freshwater) value of ≤0.043 mg/l would correspond to a long-term EC10 or NOEC value of ≤0.43 mg/l when applying an assessment factor of 10, indicating high toxicity which was not observed in the short- and existing long-term dataset. Therefore, a long-term fish study is not considered to be necessary, as the results are unlikely to impact the existing environmental exposure assessment.


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 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.