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EC number: 242-056-0
CAS number: 18171-19-2
Due to the rapid hydrolysis of the
substance, the chemical safely assessment is based on the silanol
hydrolysis product 3-chloropropyl(methyl)silanediol.
Testing for toxicity to
terrestrial organisms 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 or short-term terrestrial toxicity to
invertebrates or higher plants study 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 below 1, and therefore the risk is already
adequately controlled and further testing is not justifiable.
The silanol hydrolysis product is
not readily biodegradable but has low potential for bioaccumulation and
low potential for adsorption (based on log Kow <3
(0.8) and low log Koc (1.4)); partitioning to the terrestrial
compartment is expected to be minimal. Toxicity was only observed at
very high concentrations in aquatic tests and there is no reason to
expect any specific mechanism of toxicity beyond narcosis. Therefore,
the occurrence of more severe toxic effects in the terrestrial
compartment that were not expressed in the aquatic studies would be
is classed as Hazard Category 3 for the terrestrial environment (Table
R.7.11-2 of ECHA guidance R7.c, 2017) based on potential for high
persistence (DT50 >180 days), lack of ready biodegradability
and low toxicity to aquatic organisms (EC/LC50 not <1 mg/l).
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
3-chloropropyl(methyl)silanediol is derived from the short-term test
result with algae and has a value of 0.22 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
3-chloropropyl(dimethoxy)methylsilane (CAS 18171-19-2), the highest
PECx10/PNECscreen (EQPM) for 3-chlorpropyl(methyl)silanediol is (1.91E-3
x 10) / 0.22 = RCR 8.7E-2. The highest agricultural RCR is therefore
well below 1 indicating that one confirmatory long-term terrestrial
toxicity test is required according to ECHA guidance Chapter R.7c (ECHA
2017), and if toxicity is shown in the confirmatory test then full
testing according to Annex X would be required.
However, in the event that
terrestrial invertebrate and plant studies were conducted, the
definitive terrestrial risk characterisation would use a PNECsoil based
on the lower of the two test results with an assessment factor of 50
(unless soil microorganism data are available as well, in which case,
the assessment factor would be 10).
Full testing in both terrestrial
plants and invertebrates would result in a new value of PNECsoil. This
value could only be more conservative than the value of
PNECscreen(EQPM), in the situation that standard testing in terrestrial
plants or invertebrates exhibited a dose response with a NOEC/EC10 ≤11
mg/kg dw. There is no basis to expect such toxicity for
3-chloropropyl(methyl)silanediol based on the absence of significant
toxicity observed in aquatic tests and the low potential for
In the case of
3-chloropropyl(methyl)silanediol, 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 (including the confirmatory study) is not necessary.
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.
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,
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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