Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 221-906-4
CAS number: 3277-26-7
Gene mutation (Bacterial reverse mutation assay / Ames test): negative
with and without metabolic activation in Salmonella typhimurium strains
TA 98, TA 100, TA 1535 and TA 1537 and E.coli WP2uvrA (OECD Test
Guideline 471) (Dow Corning Corporation, 2009).
Cytogenicity in mammalian cells: read-across from analogous substance
hexamethyldisiloxane: negative with and without metabolic activation in
cultured human lymphocytes (similar to OECD Test Guideline 473) (Hita
Research Laboratories, 1995).
Cytogenicity in mammalian cells: read-across from analogous substance
2,4,6,8-tetramethylcyclotetrasiloxane: negative with and without
metabolic activation in peripheral human lymphocytes (OECD Test
Guideline 473) (Harlan Cytotest Cell Research, 2010).
Mutagenicity in mammalian cells: read-across from analogous substance
hexamethyldisiloxane: negative in L5178Y mouse lymphoma cells (similar
to OECD Test Guideline 476) (Litton Bionetics, 1978).
results – Experiment I
+/- metabolic activation
Average number of colony counts
results of Experiment II
No treatment related increase in the
percentage of cells with abarrations was observed with or without
activation. No treatment-related polyploidy was observed.
The symbols used in Tables 2 and 3 are -
negative; ++ positive (20% to lower than 50%); +++ positive (50% or
2: Results of chromosome analysis - without activation (% from total
count from 2 cultures, 200 cells counted)
Exposure time (h)
% polyploid cells
% cells with aberrations inc gaps
% cells with aberrations not inc gaps
3: Results of chromosome analysis - with and without activation, 6 h
exposure (% from total count from 2 cultures, 200 cells counted)
4: Toxicity data
Without metabolic activation
With metabolic activation
24 h treatment
48 h treatment
Growth rate %*
* Mean value of relative rate of cell growth
for two flasks
** Precipitation was observed
The following symbols apply to Table 4; not
all are clearly defined in the report: +++ sufficient; ++ moderate;
+rate (sic); +/- extremely [low] rate; - none
Summary of results of the
chromosomal aberration study with 2,4,6,8-tetramethylcyclotetrasiloxane
Exposure period 4 hrs without S9 mix
Exposure period 22 hrs without S9 mix
Exposure period 4 hrs with S9 mix
cells carrying exchanges
occurred at the end of treatment
frequency statistically significant higher than corresponding control
0.5 % (v/v)
2 EMS 825.0
3 EMS 770.0
4 CPA 7.5
The test item
2,4,6,8-tetramethylcyclotetrasiloxane, dissolved in ethanol, was
assessed for its potential to induce structural chromosomal
aberrations in human lymphocytes in vitro in
two independent experiments. The following study design was performed:
Without S9 mix
With S9 mix
Exp. I & II
In each experimental group two parallel
cultures were analysed. Per culture 100 metaphases were scored for
The highest applied concentration in this
study (2400.0 μg/ml of the test item, approx. 10 mM) was chosen with
regard to the molecular
weight of the test item and with respect to
the current OECD Guideline 473.
Dose selection of the cytogenetic experiment
was performed considering the toxicity data and the occurrence of test
item precipitation in
accordance with OECD Guideline 473.
In the absence and presence of S9 mix, no
cytotoxicity was observed up to the highest applied concentration.
In both independent experiments, neither a
statistically significant nor a biologically relevant increase in the
number of cells carrying
structural chromosomal aberrations was
observed after treatment with the test item.
No evidence of an increase in polyploid
metaphases was noticed after treatment with the test item as compared to
the control cultures.
Appropriate mutagens were used as positive
controls. They induced statistically significant increases (p < 0.05) in
cells with structural
Table 1 Summary of mouse lymphoma
Mammalian Bone Marrow Chromosome Aberration Test in rat (ip study)
(similar to OECD Test Guideline 475): read-across from analogous
substance hexamethyldisiloxane: negative (Dow Corning Corporation, 1991).
controls: frequencies of breaks were 0.54%, 2.49% and 1.47% at
sacrifice at 6, 24 and 48 hours respectively.
of chromosome analysis in rat bone marrow cells
Low dose (255 mg/kg bw)
Mid dose (515 mg/kg bw)
High dose (1030 mg/kg bw)
Sampling time (h)
Number of cells evaluated
Mitotic index (% range)
2 – 5
2 - 5
1 - 4
2 - 4
2 - 5
4 - 7
1 - 6
3 - 5
= Not Reported
1,1,3,3-Tetramethyldisiloxane (H2-L2) has been tested for mutagenicity
to bacteria, in three studies. The key study was conducted according to
OECD Test Guideline 471, in compliance with GLP (Dow Corning
Corporation, 2009). No evidence of a test substance related increase in
the number of revertants was observed with or without activation in
Salmonella typhimurium strains TA 98, TA 100, TA 1535 and TA 1537 and
E.coli WP2uvrA in the initial or the repeat experiments. Appropriate
solvent and positive controls were included and gave expected results.
It is concluded that the test substance is negative for mutagenicity to
bacteria under the conditions of the test. This result is supported by
two further reliable studies in bacteria, both of which reported
negative results in appropriate ranges of bacterial strains (LPT, 2002)
and Genetic Laboratory, 2006).
The available bacterial mutagenicity data for hexamethyldisiloxane
(HMDS) have been included to the dataset to support read across for
The structural analogue hexamethyldisiloxane (HMDS) has been tested for
cytogenicity, according to a protocol that is similar to OECD Test
Guideline 473 and in compliance with GLP (Hita Research Laboratories,
1995). The test substance did not induce any chromosome aberrations with
or without metabolic activation. There were no marked differences
between replicate flasks. Expected results were obtained from vehicle
and positive controls. It is concluded that the test substance is
non-clastogenic (does not induce chromosome aberrations) in Chinese
hamster lung cells under the conditions of the test.
In addition, to demonstrate that the Si-H group does not cause in vitro
genetic toxicity, supporting data are used from a cyclic siloxane which
contains this group, 2,4,6,8-tetramethylcyclotetrasiloxane (H-D4). H-D4
has been tested according to OECD Test Guideline 473 and in compliance
with GLP (Harlan Cytotest Cell Research, 2010). No statistically
significant nor biologically relevant increase in the number of cells
carrying structural chromosomal aberrations was observed with or without
activation in either the initial or repeat experiments. It is concluded
that the test substance is negative for the induction of chromosome
aberrations in mammalian cells under the conditions of the study.
Information on the mutagenicity to mammalian cells is provided by the
structural analogue hexamethyldisiloxane (HMDS) which has been tested
for mutagenicity in L5178Y cells in a reliable study conducted according
to a protocol that is similar to OECD Test Guideline 476 (Litton
Bionetics, 1978). The test substance did not cause a biologically
significant increase in the mutation frequency; solvent and positive
controls gave expected results. It is concluded that the test substance
is not mutagenic under the conditions of the test.
Further information on the cytogenicity is provided by the structural
analogue hexamethyldisiloxane (HMDS) which has been tested for the
induction of chromosome aberrations in rat bone marrow cells in a valid
in vivo study (Dow Corning Corporation, 1991). No evidence of the
induction of chromosomal damage in the bone marrow cells of rats
following i.p. injection was observed. The test substance is considered
to be non-clastogenic (negative for the induction of chromosome
aberrations) in rat bone marrow cells under the conditions of the test.
Based on the available in vitro and in vivo information,
tetramethyldisiloxane is not classified for mutagenicity according to
Regulation (EC) No 1272/2008.
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.
Welcome to the ECHA website. This site is not fully supported in Internet Explorer 7 (and earlier versions). Please upgrade your Internet Explorer to a newer version.
Do not show this message again