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EC number: 217-983-9
CAS number: 2031-67-6
Triethoxy(methyl)silane (CAS 2031 -67 -6) is part of a group of
organosilicones, the toxicity of which is determined by a non-polar
mechanism of toxicity, and as such log Kow drives toxicity. Substances
in this group include alkoxy- and chloro-silanes having secondary
features that do not affect the toxicity of the substances. Additional
information is given in a supporting report (PFA,
2013) attached in Section 13 of the IUCLID dossier.
Measured data were available for the acute toxicity of
triethoxy(methyl)silane (CAS 2031-67-6) for fish, invertebrates and
algae. In the studies selected as key, for each of the trophic level, no
effects were observed at the test concentration of 500 mg/l (nominal)
for Danio rerio (OECD Guideline 203), Daphnia magna (OECD Guideline 202)
and algae (OECD Guideline 201). Several supporting studies were also
available for fish, algae and invertebrates. The supporting studies
reported an LC50 of >1000 mg/l for fish (Fundulus heteroclitus and
Lepomis macrochrius), an EC50 of >1000 mg/l for invertebrates (Daphnia
magna) and an EC50 of >1000 mg/l for algae (Selenastrum capricornutum).
However, the substance rapidly hydrolyses (half-life approximately
5.5 hours) to methylsilanetriol and ethanol. REACH guidance (ECHA 2010A,
R.16) states that “for substances where hydrolytic DT50 is less than 12
hours, environmental effects are likely to be attributed to the
hydrolysis product rather than to the parent itself”. TGD and ECHA
guidance (EC 2003, ECHA 2010A) also suggest that when the hydrolysis
half-life is less than 12 hours, the breakdown products, rather than the
parent substance, should be evaluated for aquatic toxicity. Therefore,
the environmental hazard assessment, including sediment and soil
compartments due to pore water, is based on the properties of the
silanol hydrolysis product, in accordance to REACH guidance. As
described in Section 1, condensation reactions of the silanetriol are
- Considerations on the non-silanol hydrolysis products:
Methanol and ethanol are well characterised in the public domain
literature and are not hazardous at concentrations relevant for the
studies; the short-term EC50 and LC50 values for these substances are in
excess of 1000 mg/l (OECD 2004a - SIDS for methanol, CAS 67-56-1, OECD
2004b - SIDS for ethanol, CAS 64-17-5).
QSAR data were derived via calculations for the silanol hydrolysis
product and all trophic levels. These data were used to
derive PNECs. A 96-h LC50 of 10000 mg/l was determined for fish, a 48-h
LC50 of 29600 mg/l for aquatic invertebrates and a 96-h EC50 of 2115
mg/l for algae.
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.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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