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EC number: 220-449-8
CAS number: 2768-02-7
No terrestrial toxicity data are
available with the registered substance. Terrestrial testing is
currently waived 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 long-term terrestrial toxicity studies because, as
indicated in guidance R.7.11.6 (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
The silanol hydrolysis product,
vinylsilanetriol (CAS 143-48-6), upon which the chemical safety
assessment is based, is highly water soluble and has a low log Kow value
and therefore, exposure of the soil compartment is expected to be low.
Vinylsilanetriol has a low
potential for adsorption (based on log Koc -0.02), low
potential for bioaccumulation (based on log Kow <3 (-2.0))
and there is no reason to expect any specific mechanism of toxicity
In the context of the Integrated
Testing Strategy for the terrestrial compartment (ECHA guidance Chapter
R.7c, terrestrial hazard classification scheme, Table R.7.11-2) (ECHA
2017) the aquatic toxicity tests do not indicate that the substance is
very toxic (EC/LC50 >1 mg/l for algae, Daphnia and
fish). However, despite rapid degradation of the parent substance, the
silanol hydrolysis product, vinylsilanetriol, is not readily
biodegradable and may persist in the environment. The substance is
therefore assigned to Hazard Category 3.
In this situation, a screening
approach is applied: a confirmatory long-term terrestrial test is
usually appropriate, in addition to the equilibrium partitioning
approach with an extra factor of ten, in order to determine whether
further full tests are necessary.
The PNECscreen(EQPM) for
vinylsilanetriol is derived from the long-term test result with Daphnia
and has a value of 0.06 mg/kg dwt. For the purpose of the screening
assessment comparison only, an extra factor of ten is applied
(PECx10/PNECscreen(EQPM)). Based on the exposure assessment
of the silanol hydrolysis product, the highest terrestrial (PECx10)/PNECscreen(EQPM)
for vinylsilanetriol is (0.00437 x 10) / 0.06 = 0.728.
A confirmatory long-term
terrestrial toxicity test is therefore required in accordance with the
recommendations for Hazard Category 3 substances.
No toxicity was observed in the
aquatic microorganism tests, therefore a toxicity to soil microorganisms
test is not required.
However, prior to terrestrial
toxicity tests being carried out, the technical feasibility of testing
the silanol hydrolysis product, vinylsilanetriol, would need to be
assessed. To achieve the test concentrations required by terrestrial
testing guidance (up to 1000 mg/kg), aqueous stock solutions would need
to be prepared at very high concentrations, well above 1000 mg/l.
Silanetriols are susceptible to condensation reactions. Condensation of
vinylsilanetriol is expected to become important at loadings above about
1000 mg/l, causing the formation of insoluble polymeric particles (sols)
and gels over time. It therefore may not be possible to test terrestrial
organisms at high enough test concentrations to meaningfully assess the
terrestrial toxicity of vinylsilanetriol. Prior to any testing, the
feasibility of dosing at concentrations up to 1000 mg/kg dw would have
to be assessed. Further details on technical feasibility of terrestrial
testing with silanetriol substances are given in Annex 4 of the CSR and
attached in Section 13 of IUCLID.
In addition, if a confirmatory
long-term terrestrial test were to be conducted, an assessment factor of
100 would be applied to derive PNECsoil from one long-term
test. For this value to be more conservative than the PNECsoil derived
by the equilibrium partitioning method, the NOEC derived in the
terrestrial test would have to be <6 mg/kg dw. There is no basis to
expect such toxicity for vinylsilanetriol based on the absence of
significant toxicity observed in aquatic tests and the low potential for
adsorption to and bioaccumulation in soil.
In the case of vinylsilanetriol,
the Registrant considers that a long-term terrestrial study is unlikely
to affect the outcomes of the chemical safety assessment. As such the
Registrant proposes that further testing is currently not necessary.
Details on how the PNEC and the
risk characterisation ratio have been derived can be found in IUCLID
Section 6.0, and Chapters 7, 9 and 10 of the Chemical Safety Report.
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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