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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 2017), 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.
In the event that
terrestrial invertebrate and plant studies need to be 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).
A confirmatory test would be
conducted with the most sensitive organism group based on short-term
aquatic testing. For this substance, algae were the most sensitive
organisms in the short-term tests, indicating a preference to conduct a
confirmatory test with terrestrial plants.
The PNECscreen(EQPM) for
3-chloropropyl(methyl)silanediol is derived from the short-term test
results 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, the
highest agricultural soil RCR available for the silanol hydrolysis
product, 3-chloropropyl(methyl)silanediol is 0.00867, with a
corresponding Predicted Environmental Concentration (PEC) of 0.00191
mg/kg dwt. The (PECx10)/PNECscreen(EQPM) for
3-chloropropyl(methyl)silanediol is (0.00191*10)/ 0.22 = screening RCR
A confirmatory long-term
terrestrial toxicity test is therefore required in accordance with the
recommendations for hazard category 3 substances. 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. A
confirmatory test with either terrestrial plants or invertebrates would
result in a new value for 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 ≤ 22 mg/kg dw (and applying an
assessment factor of 100). There is no basis to expect such toxicity for
3-chloropropyl(methyl)silanediol based on the absence of significant
toxicity observed in aquatic tests.
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 testing is not
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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