Registration Dossier
Registration Dossier
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EC number: 236-818-1 | CAS number: 13497-18-2
Endpoint summary
Administrative data
Description of key information
In accordance with REACH Annex XI, Section 3, there is no need to further investigate the effects of the silanol hydrolysis product 3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine in short- or long-term terrestrial toxicity studies because exposure of terrestrial organisms to 3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine is absent or not significant (RCR << 1). The hazard assessment based on acute aquatic toxicity data shows no toxicity toward aquatic organisms of all three trophic levels (all acute effect values, i.e. E(L)C50s were > 100 mg/L). The substance is well soluble and thus, greater toxicity in long-term tests is unlikely. Therefore, the risk is already adequately controlled and further testing is not justifiable.
The hydrolysis half-life of the registered compound (DT50 = 11.9 h at pH 7 and 20 °C) is close to the cut-off value of 12 h, which is suggested by ECHA (2016) for basing the environmental risk assessment either on the hydrolysis products or the parent substance itself. For the sake of completeness, the environmental hazard and risk assessment in the present dossier did also consider the impact of the parent compound, although the hydrolysis products are expected to be predominantly present. Equally to the silanol hydrolysis product, the risk assessment for the parent compound did not show any risk for the terrestrial compartment (RCR << 1).
Additional information
The hydrolysis half-life of the registration substance is 11.9 h at pH 7 and 20 °C. Considering the long duration of long-term terrestrial tests, the hazard assessment for the terrestrial compartment is based on the silanol hydrolysis product 3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine. The other hydrolysis product, ethanol, is known for its absence of environmental toxicity (OECD SIDS, 2004).
In accordance with REACH Annex XI, Section 3, there is no need to further investigate the effects of the silanol hydrolysis product 3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine in short- or long-term terrestrial toxicity studies because exposure of terrestrial organisms to 3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine is absent or not significant (RCR << 1). The hazard assessment based on acute aquatic toxicity data with the parent compound shows no toxicity toward aquatic organisms of all three trophic levels (all acute effect values, i.e. E(L)C50s were > 100 mg/L). Due to the fast hydrolysis half-life of the parent compound and the duration of the standard acute aquatic toxicity tests (48 up to 96 hours), the organisms can be assumed to be predominantly exposed to the hydrolysis products. The silanol hydrolysis product is well soluble and thus, greater toxicity in long-term tests is unlikely. Therefore, the risk is already adequately controlled and further testing is not justifiable.
In addition, testing for toxicity to terrestrial organisms is not considered necessary because:
-The silanol hydrolysis product, 3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine, upon which the chemical safety assessment for the terrestrial compartment is based, is highly water-soluble and has a low expected log Pow value (-4.0, QSAR) and therefore, exposure of the soil compartment is expected to be low.
- 3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine has a low potential for adsorption (log Koc = 0.49; QSAR) and low potential for bioaccumulation (BCF < 4.2, RA to CAS 82985-35-1) and there is no reason to expect any specific mechanism of toxicity beyond narcosis.
-Terrestrial testing is technically difficult for trialkoxysilanes in general due to condensation reactions at high test-concentrations. A feasibility study is currently ongoing. For further information, please see attached justification IUCLID chapter 13.
-No toxicity was observed in the aquatic microorganism tests, therefore a toxicity to soil microorganisms test is not required.
Overall, it is concluded that the risk characterisation conclusion is sufficiently conservative in respect of any uncertainties and therefore further testing is not considered necessary. Details on how the PNEC and the risk characterisation ratio have been derived can be found in Chapters 7, 9 and 10 of the Chemical Safety Report.
References:
OECD SIDS, 2004. Ethanol - SIDS Initial Assessment Report For SIAM 19, Berlin, Germany: UNEP Publications.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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