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EC number: 221-906-4
CAS number: 3277-26-7
Table 1. Cumulative mortality:
Concentration Number Dead/Number Exposed (hours)
(mg/L) 0 24 48 72 96
0 0/20 0/20 0/20 0/20 1/20
65 0/20 0/20 0/20 0/20 0/20
128 0/20 0/20 0/20 0/20 0/20
250 0/20 0/20 0/20 1/20 8/20
481 0/20 0/20 8/20 9/20 20/20
949 0/20 6/20 20/20 20/20 20/20
No mortality or other effects were observed in the Control or treated
Short-term toxicity to fish: 96-h LC50: 271 mg/l (measured, arith. mean) (OECD 203), read-across from an analogous/structurally related substance trimethylsilanol (CAS 1066-40-6).
are no reliable short-term toxicity to fish data for
1,1,3,3-tetramethyldisiloxane (CAS 3277-26-7), therefore good quality
data have been read across from the following substances:
trimethylsilanol (CAS 1066-40-6), based on the substance being an
analogue of the intermediate hydrolysis product dimethylsilanol.
the tests with trimethylsilanol and dimethylsilanediol, the observations
are attributed to the exposure of test organisms to the test substance.
(TMS, CAS 1066-40-6) has the potential to condense to form
hexamethyldisiloxane (HMDS, CAS 107-46-0), which may be present at low
levels in the test system. HMDS is classified as Aquatic Acute 1 H400
and Aquatic Chronic 2 H411
therefore its presence has the possibility to impact the results.
However, the estimated concentration of HMDS is 0.04, 0.2, 0.3, 0.6 and
0.9 mg/l at 100, 200, 300, 400 and 500 mg/l of TMS respectively and
there was no reporting of undissolved test material or droplets being
formed, which would otherwise clearly indicate the formation of HMDS. In
addition, the log Kow of
trimethylsilanol (1.62) is such that effects may be observed at high
concentrations in short-term studies.
Therefore the effects seen in the short-term toxicity to fish study,
such as 40% mortality at 250 mg/l test concentration, may
be attributable to TMS alone and the study is considered to be
conservative and reliable for the purpose of this assessment.
registered substance also releases hydrogen during its final hydrolysis.
Hydrogen is not thought to contribute to the toxicity of the substance
and is discussed further in the ecotoxicological information overview
endpoint summary (additional information).
results of the studies with the source substance are:
to the discussion in the Section 6 endpoint summary (Section 7.0 of CSR)
for further discussion of the approach to chemical safety assessment for
this registration substance, and justification for read-across used.
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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