Registration Dossier
Registration Dossier
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EC number: 946-797-7 | CAS number: -
Endpoint summary
Administrative data
Key value for chemical safety assessment
Genetic toxicity in vitro
Description of key information
There are no available genetic toxicity studies for the registered substance "Reaction Mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane". Therefore, data have been read-across from its four constituents: HMDS, L3, L4 and L5.
Bacterial mutagenicity: HMDS, L3 and L4 were negative with and without metabolic activation in Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and E. coli WP2 uvrA (OECD 471).
Cytogenicity in mammalian cells: HMDS, L3 and L5 were negative with and without metabolic activation in Chinese hamster lung or V79 cells (OECD 473).
Mutagenicity in mammalian cells: HMDS and L4 were negative with and without metabolic activation in mouse lymphoma L5178Y (OECD 476).
Link to relevant study records
- Endpoint:
- in vitro gene mutation study in bacteria
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 1994-03-24 to 1994-04-11
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- guideline study with acceptable restrictions
- Remarks:
- The restrictions were that duplicate plates were used, not triplicate, and 2-amino anthracene was the only control with metabolic activation. An authorised translation was available to the reviewer.
- Qualifier:
- according to guideline
- Guideline:
- JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 471 (Bacterial Reverse Mutation Assay)
- Deviations:
- yes
- Remarks:
- only duplicate plates; 2-AA only control +MA
- Principles of method if other than guideline:
- E coli Reverse mutation assay
- GLP compliance:
- yes
- Type of assay:
- bacterial reverse mutation assay
- Target gene:
- histidine operon (Salmonella strains); tryptophan operon (E. coli)
- Species / strain / cell type:
- S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
- Metabolic activation:
- with and without
- Metabolic activation system:
- phenobarbital and 5,6-benzoflavone induced rat liver S9
- Test concentrations with justification for top dose:
- 50 to 10000 µg/plate (range-finding);
- Vehicle / solvent:
- - Vehicle(s)/solvent(s) used: acetone (dehydrated)
- Justification for choice of solvent/vehicle: insoluble in water - Untreated negative controls:
- yes
- Remarks:
- sterility control
- Negative solvent / vehicle controls:
- yes
- Remarks:
- acetone
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- furylfuramide
- Remarks:
- AF-2: TA98, TA 100 and E. coli WP2 uvrA without metabolic activation 0.1 µg/plate (TA 98); 0.01 µg/plate (TA 100 and E. coli)
- Untreated negative controls:
- yes
- Remarks:
- sterility control
- Negative solvent / vehicle controls:
- yes
- Remarks:
- acetone
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- sodium azide
- Remarks:
- NaN3: TA 1535 without metabolic activation 0.5 µg/plate
- Untreated negative controls:
- yes
- Remarks:
- sterility control
- Negative solvent / vehicle controls:
- yes
- Remarks:
- acetone
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: 2-methoxy-6-chloro-9(3-(2-chloroethyl)-aminopropylamino) acridine 1µg/plate
- Remarks:
- ICR-191: TA 1537 without metabolic activation
- Untreated negative controls:
- yes
- Remarks:
- sterility control
- Negative solvent / vehicle controls:
- yes
- Remarks:
- acetone
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: 2-aminoanthracene: µg/plate: 0.5 (TA 98), 1 (TA 100), 2 (TA1535 and 1537) and 1 (E.coli)
- Remarks:
- 2AA: all strains with metabolic activation
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: preincubation
DURATION
- Preincubation period: 30 minutes
- Exposure duration: 48 hours
SELECTION AGENT (mutation assays): minimal agar
NUMBER OF REPLICATIONS: duplicate (triplicate for solvent controls); range-finding and main experiments evaluated.
DETERMINATION OF CYTOTOXICITY
- Method: other: condition of bacterial lawn; reduction in number of revertants
OTHER: ACTIVATION: S9 mix included glucose-6-phosphate, NADP and NADPH as cofactors, and 10% S9. 1.5 ml S9 mix was added to 0.3 ml of bacteria and 0.15 ml test substance -concentration of S9 was therefore approximately 7.5% during pre-incubation. - Evaluation criteria:
- The test substance was judged positive if the number of revertants was more than twice the negative control, and the response was dose-dependent and reproducible.
- Key result
- Species / strain:
- S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- valid
- Positive controls validity:
- valid
- Conclusions:
- Hexamethyldisiloxane has been tested according to a Japanese guideline that is similar to OECD 471 and under GLP, using the pre-incubation method. No evidence of test-substance induced increase in the number of revertants was observed in Salmonella typhimurium strains TA1535, TA1537, TA98, TA100 or E. coli WP2 uvrA, with or without metabolic activation, up a concentration exceeding current limit concentrations in either the dose finding test or the main assay. Appropriate solvent, positive and sterility 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 substance.
- Endpoint:
- in vitro cytogenicity / chromosome aberration study in mammalian cells
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- other: Japan notification on partial revision of testing methods relating to new chemical substances nos 700, 1039 and 1014
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
- GLP compliance:
- yes
- Type of assay:
- in vitro mammalian chromosome aberration test
- Species / strain / cell type:
- mammalian cell line, other: CHL cells clone 11
- Metabolic activation:
- with and without
- Metabolic activation system:
- Phenobarbital, 5,6 benzoflavone induced rat liver S9
- Test concentrations with justification for top dose:
- 31.25 to 125 µg/ml (without), 100 to 400 µg/ml (with metabolic activation)
- Vehicle / solvent:
- - Vehicle(s)/solvent(s) used: 0.5% methylcellulose aqueous solution was used to prepare suspensions of the test substance. Suspensions were used within 2 hours of preparation.
- Justification for choice of solvent: none given in report - Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- mitomycin C
- Remarks:
- without activation
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- cyclophosphamide
- Remarks:
- with activation
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: in suspension, added to medium
DURATION
- Exposure duration: 6 hours with activation, 24 and 28 hours without
- Expression time (cells in growth medium): 24 or 48 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 24 or 48 hours
SPINDLE INHIBITOR (cytogenetic assays): colcemid added 2 hours before end of incubation period
STAIN (for cytogenetic assays): Giesma
NUMBER OF REPLICATIONS: duplicate cultures for each dose
NUMBER OF CELLS EVALUATED: 200
DETERMINATION OF CYTOTOXICITY
- Method: other: cell growth inhibition and cell division inhibition
OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: yes
- Other: chromatid and chromosome structural aberrations (gap, break, exchange etc) were recorded. A gap was defined as a clear discontinuity, wider than one chromatid but narrower than two, accompanied by minimal misalignment of the chromatid. - Evaluation criteria:
- A dose related, reproducible increase in the incidence of cells with any aberration including gaps was evaluated as positive if the increase was 10% or more. An increase of 5% or more was evaluated as suspect positive, and an incidence of lower than 5% was evaluated as negative.
- Key result
- Species / strain:
- Chinese hamster lung fibroblasts (V79)
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- 100 µl/ml (without activation); 300 µg/ml (with activation)
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Conclusions:
- Hexamethyldisiloxane has been tested under GLP in a valid Japanese guideline study according to a protocol that is similar to OECD TG 473. 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.
- Endpoint:
- in vitro gene mutation study in mammalian cells
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- guideline study with acceptable restrictions
- Remarks:
- The restrictions were that the test concentrations were not duplicated.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
- Deviations:
- yes
- Remarks:
- no duplicates
- GLP compliance:
- no
- Type of assay:
- mammalian cell gene mutation assay
- Species / strain / cell type:
- mouse lymphoma L5178Y cells
- Metabolic activation:
- with and without
- Metabolic activation system:
- mouse liver S9
- Test concentrations with justification for top dose:
- 0.0125, 0.025, 0.05, 0,1, 0.2 µl/ml
- Vehicle / solvent:
- - Vehicle(s)/solvent(s) used: ethanol
- Untreated negative controls:
- yes
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- ethylmethanesulphonate
- Remarks:
- without activation
- Untreated negative controls:
- yes
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- N-dimethylnitrosamine
- Remarks:
- with activation
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: in medium
DURATION
- Exposure duration: 4 hours
- Expression time (cells in growth medium): 3 days
- Selection time (if incubation with a selection agent): 10 days
SELECTION AGENT (mutation assays): BUdR
NUMBER OF REPLICATIONS: no replicates
DETERMINATION OF CYTOTOXICITY
- Method: other: loss of growth potential - Evaluation criteria:
- A substance is considered mutagenic if there is a dose response relationship over 3 dose levels; minimum increase at high level of dose response is at least times greater than the solvent control value; solvent control data are within normal range of spontaneous background mutation rates.
- Statistics:
- No statistical analysis was carried out.
- Key result
- Species / strain:
- mouse lymphoma L5178Y cells
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- at 0.2 µl/ml, equivalent to approximately 200 µg/ml
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- valid
- Positive controls validity:
- valid
- Additional information on results:
- Preliminary cytotoxicity testing indicated toxicity at > 0.2 µl/ml
Several scattered increases were thought by the authors to be the result of spurious fluctuations and cytotoxicity. - Conclusions:
- Hexamethyldisiloxane has been tested for mutagenicity in L5178Y cells in a valid and reliable study according to a protocol that is similar to OECD TG 476. 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.
- Endpoint:
- in vitro gene mutation study in bacteria
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 2007-12-28 - 2008-01-23
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 471 (Bacterial Reverse Mutation Assay)
- GLP compliance:
- yes (incl. QA statement)
- Type of assay:
- bacterial reverse mutation assay
- Species / strain / cell type:
- S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
- Species / strain / cell type:
- E. coli WP2 uvr A
- Metabolic activation:
- with and without
- Metabolic activation system:
- Aroclor 1254 induced rat liver S9
- Test concentrations with justification for top dose:
- 50, 150, 500, 1500 and 5000 µg/plate
- Vehicle / solvent:
- - Vehicle(s)/solvent(s) used: Acetone
- Justification for choice of solvent/vehicle: none given - Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: 2-aminoanthracene 1 µg/plate
- Remarks:
- TA98, TA100, TA1535 and TA1537 with metabolic activation
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: 2-aminoanthracene 10 µg/plate
- Remarks:
- WP2 uvrA with metabolic activation
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- 2-nitrofluorene
- Remarks:
- TA98 without metabolic activation: 1 µg/plate
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- sodium azide
- Remarks:
- TA100 and TA1535 without metabolic activation: 1 µg/plate
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- 9-aminoacridine
- Remarks:
- TA1537 without metabolic activation: 75 µg/plate
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- methylmethanesulfonate
- Remarks:
- WP2 uvrA without metabolic activation: 1000 µg/plate
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: in agar (plate incorporation)
ACTIVATION: S9 mix contained 10% S9, and glucose-6-phosphate and NADP as co-factors. 0.5 ml S9 mix was added to 2.0 ml top agar giving a final concentration of approximately 2% S9.
DURATION
- Exposure duration: 48 - 72 hours
NUMBER OF REPLICATIONS: experiment 1 - duplicate plates, experiment 2 - triplicate plates
DETERMINATION OF CYTOTOXICITY
- Method: other: condition of background lawn - Evaluation criteria:
- A result is positive if the mean of each positive control exhibits at least a 3-fold increase in the number of revertants over the mean value of the respective vehicle control. A minimum of three non-toxic dose levels were required to evaluate assay data. Strains TA1535 and TA1537 were judged positive if there was a 3-fold increase in the number of revertants compared with the mean vehicle control value and a 2-fold increase for Salmonella typhimurium strains TA98, TA100 and E. coli WP2 uvrA.
- Statistics:
- None stated in report
- Key result
- Species / strain:
- S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Key result
- Species / strain:
- E. coli WP2 uvr A
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Additional information on results:
- TEST-SPECIFIC CONFOUNDING FACTORS
COMPARISON WITH HISTORICAL CONTROL DATA: Historical negative and positive control values included in report
ADDITIONAL INFORMATION ON CYTOTOXICITY: Cytotoxicity was not evident at any concentration - Conclusions:
- Octamethyltrisiloxane has been tested for mutagenicity to bacteria in a study which was conducted according to OECD 471, and in compliance with GLP. No evidence of a test substance related increase in the number of revertants was observed with or without activation in the initial or the repeat experiments with Salmonella typhimurium strains TA 98, 100, 1535, 1537 and E.coli WP2 uvrA. Appropriate positive and solvent controls were tested and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.
- Endpoint:
- in vitro cytogenicity / chromosome aberration study in mammalian cells
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 2008-10-07 - 2008-10-26
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
- Qualifier:
- according to guideline
- Guideline:
- other: EPA (TSCA) GLP 40 CFR Part 792
- GLP compliance:
- yes (incl. QA statement)
- Type of assay:
- in vitro mammalian chromosome aberration test
- Species / strain / cell type:
- Chinese hamster Ovary (CHO)
- Details on mammalian cell type (if applicable):
- - Type and identity of media: McCoy's 5A medium inc 10% FBS, 100 units penicillin/ml, 100 µg streptomycin/ml, 2mM L-glutamine
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes, cell stocks not used beyond passage 20 to ensure karyotype stability
- Periodically "cleansed" against high spontaneous background: no information - Metabolic activation:
- with and without
- Metabolic activation system:
- Aroclor 1254 induced rat liver S9
- Test concentrations with justification for top dose:
- 4 hours (-MA): 2.5, 5, 12.5 µg/ml; 20 hours (-MA): 5, 10, 15 µg/ml; 4 hours (+MA): 10, 25 and 75 µg/ml.
- Vehicle / solvent:
- - Vehicle(s)/solvent(s) used: Acetone
- Justification for choice of solvent/vehicle: none given in report - Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- mitomycin C
- Remarks:
- 4 hours without metabolic activation: 0.2 µg/ml
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- cyclophosphamide
- Remarks:
- 4 hours with metabolic activation: 10 µg/ml
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- mitomycin C
- Remarks:
- 20 hours without metabolic activation: 0.1 µg/ml
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: in medium
DURATION
- Expression time (cells in growth medium): 48 hours
- Selection time (if incubation with a selection agent):
- Fixation time (start of exposure up to fixation or harvest of cells): 24 hours
SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): 5% Giemsa
NUMBER OF REPLICATIONS: duplicate cultures
NUMBER OF CELLS EVALUATED: 200 per dose level
DETERMINATION OF CYTOTOXICITY
- Method: cell growth inhibition
ACTIVATION:
Aroclor 1254-induced rat liver S9: S9 mix included glucose-6-phosphate and NADP as co-factors. - Evaluation criteria:
- The test article was considered to induce a positive response when the percentage of cells with aberrations was increased in a dose responsive manner with one or more concentrations being statistically significant (p<0.05). Values that are statistically significant but do not exceed the range of historical solvent controls may be judged as not biologically significant.
- Statistics:
- Fisher's Exact test and the Cochran-Armitage test to measure dose responsiveness.
- Key result
- Species / strain:
- Chinese hamster Ovary (CHO)
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- Substantial cytotoxicity observed at dose levels > 23.4 µg/ml in all three treatment groups
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Additional information on results:
- TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: pH of highest concentration approximately 7.5
- Effects of osmolality: considered acceptable, 2340 µg/ml was 281 mmol/kg, and did not exceed the osmolality of the solvent by more than 20%
- Precipitation: Visible precipitate in the form of oily droplets observed in treatment medium at 2340 µg/ml, dose levels < 702 µg/ml were soluble in treatment medium.
- Other confounding effects: none
RANGE-FINDING/SCREENING STUDIES:
COMPARISON WITH HISTORICAL CONTROL DATA: included in report
ADDITIONAL INFORMATION ON CYTOTOXICITY: - Conclusions:
- Octamethyltrisiloxane has been tested in a reliable in vitro cytogenetic assay according to OECD TG 473 and under GLP. The test substance did not induce statistically and biologically significant increases in the chromosomal aberration frequency in CHO cells. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for the induction of chromosome aberrations (is not clastogenic) in vitro under the conditions of the test.
- Endpoint:
- in vitro gene mutation study in bacteria
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 2005-09-15 to 2005-10-05
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 471 (Bacterial Reverse Mutation Assay)
- Version / remarks:
- 1997
- Deviations:
- no
- GLP compliance:
- yes
- Type of assay:
- bacterial reverse mutation assay
- Species / strain / cell type:
- S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
- Species / strain / cell type:
- E. coli WP2 uvr A
- Metabolic activation:
- with and without
- Metabolic activation system:
- Aroclor induced rat liver S9
- Test concentrations with justification for top dose:
- 50, 150, 500, 1500, 5000 µg/plate
- Vehicle / solvent:
- - Vehicle(s)/solvent(s) used: Ethanol
- Justification for choice of solvent/vehicle: Solubility properties and relative non-toxicity to bacteria - Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: 2-aminoanthracene
- Remarks:
- All salmonella strains + WP2 uvrA (with activation)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- 2-nitrofluorene
- Remarks:
- TA 98 (without activation)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- sodium azide
- Remarks:
- TA 100, TA 1535 (without activation)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- 9-aminoacridine
- Remarks:
- TA 1537 (without activation)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- methylmethanesulfonate
- Remarks:
- WP2 uvrA (without activation)
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: in agar (plate incorporation)
DURATION
- Expression time (cells in growth medium): 48 - 72 hours
NUMBER OF REPLICATIONS: 3 plates for each test concentration
DETERMINATION OF CYTOTOXICITY
- Method: relative total growth; observation of background lawn density.
METABOLIC ACTIVATION: Aroclor induce rat liver S9; S9 mix included glucose-6-phophate and NADP as co-factors. 0.5ml of 10% S9 was added to 2 ml of top agar, 0.1 ml of tester strain and 0.05 ml of vehicle or test article giving a final concentration of approximately 2%.
- Evaluation criteria:
- A result is positive if the number of revertants is significantly increased compared with the solvent control to at least 2-fold of the solvent control for TA 98, TA 100 and WP2 uvrA and 3-fold of the solvent control for TA 1535 and TA 1537. There must be a dose related increase in the mean
revertants per plate of at least one tester strain over a minimum of 2 increasing concentrations of test article.
Cytotoxicity is defined as a reduction in the number of colonies by >50% compared with the solvent control and/or at least a moderate reduction in
the background lawn (background code 3, 4 or 5). - Key result
- Species / strain:
- S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Key result
- Species / strain:
- E. coli WP2 uvr A
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Conclusions:
- Decamethyltetrasiloxane has been testing in a reliable study conducted according to OECD 471 1998 and under GLP up to limit concentrations. No increase in the number of revertants was observed at any concentration with and without metabolic activation in Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and E. coli WP2 uvrA in either the initial plate incorporation assay or the independent repeat experiment which used the pre-incubation method. It is considered that the test substance was negative for mutagenicity to bacteria under the conditions of the test.
- Endpoint:
- in vitro gene mutation study in mammalian cells
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 11 August 2009 to 14 September 2009
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Type of assay:
- mammalian cell gene mutation assay
- Species / strain / cell type:
- mouse lymphoma L5178Y cells
- Metabolic activation:
- with and without
- Metabolic activation system:
- phenobarbital and beta-naphthoflavone-induced rat liver S9
- Test concentrations with justification for top dose:
- 12.5-200 µg/ml (4h) and 1.56-50 µg/ml (24h)
- Vehicle / solvent:
- - Vehicle(s)/solvent(s) used: ethanol;
- Justification for choice of solvent/vehicle: none given in study report - Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- ethylmethanesulphonate
- Remarks:
- without metabolic activation: 400 µg/ml (4 h exposure), 150 µg/ml (24 h exposure)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- cyclophosphamide
- Remarks:
- with metabolic activation: 2 µg/ml
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: in medium
DURATION
- Exposure duration: 4 h (with and without metabolic activation); 24 h (without metabolic activation)
- Expression time (cells in growth medium): 2 days
- Selection time (if incubation with a selection agent): 10-14 days:
SELECTION AGENT (mutation assays): 5-trifluorothymidine
NUMBER OF REPLICATIONS: duplicate cultures
DETERMINATION OF CYTOTOXICITY
- Method: relative total growth; other: % viability
OTHER EXAMINATIONS:
- Other: number of small and large colonies
OTHER: a preliminary toxicity assay was conducted up to a concentration of 3107 µg/ml (10 mM) - Evaluation criteria:
- For a test material to demonstrate a mutagenic response it must produce a reproducible and dose-dependent statistically significant increase in the induced mutant frequency (IMF) over the concurrent vehicle mutant frequency value, exceeding the Global Evaluation Factor (GEF) value of 126 E10-06.
- Statistics:
- UKEMS statistical package used.
- Key result
- Species / strain:
- mouse lymphoma L5178Y cells
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- Changed to RTG 16% at 37.5 µg/ml (24h)
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Additional information on results:
- TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no marked change in pH was observed
- Effects of osmolality: did not increase by more than 50 mOsm
- Precipitation: a non interfering precipitate of the test material observed at and above 100 μg/ml in the absence of metabolic activation, and at and above 150 μg/ml in the presence of metabolic activation.
- Other confounding effects: none
RANGE-FINDING/SCREENING STUDIES: No dose-related toxicity was observed following 4 h exposure; marked toxicity was observed in the 24 h exposure group.
COMPARISON WITH HISTORICAL CONTROL DATA: Control results were within the range of historical controls
CYTOTOXICITY: The toxicity observed in the main experiment differed from that in the preliminary cytotoxicity test. No explanation of this is given in the report. - Conclusions:
- Decamethyltetrasiloxane has been tested according to OECD TG 476 and under GLP conditions for mutagenicity to mouse lymphoma L5178Y cells up to cytotoxic concentrations. No increase in mutant frequency was detected at any concentration after 4h exposure with and without metabolic activation and 24 h exposure without metabolic activation. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for the induction of mutations in L5178Y cells under the conditions of the test.
- Endpoint:
- in vitro cytogenicity / chromosome aberration study in mammalian cells
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 8 February 2012 to 5 November 2013
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
- Version / remarks:
- 1997
- Qualifier:
- according to guideline
- Guideline:
- EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)
- Version / remarks:
- 2008
- Qualifier:
- according to guideline
- Guideline:
- EPA OPPTS 870.5375 - In vitro Mammalian Chromosome Aberration Test
- Version / remarks:
- 1998
- GLP compliance:
- yes (incl. QA statement)
- Type of assay:
- in vitro mammalian chromosome aberration test
- Species / strain / cell type:
- Chinese hamster lung fibroblasts (V79)
- Details on mammalian cell type (if applicable):
- - Type and identity of media:
MEM medium supplemented with:
10 % foetal bovine serum (FBS)
100 U/100 µg/mL Penicillin/Streptomycin solution
2 mM L-glutamine
0.25 mg/mL Amphotericin
25 µM HEPES
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: no data
- Periodically "cleansed" against high spontaneous background: no data - Metabolic activation:
- with and without
- Metabolic activation system:
- phenobarbital and β naphthoflavone induced rat liver S9
- Test concentrations with justification for top dose:
- 0-10 mM
- Vehicle / solvent:
- ethanol
- Untreated negative controls:
- yes
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- ethylmethanesulphonate
- Remarks:
- without metabolic activation
- Untreated negative controls:
- yes
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- cyclophosphamide
- no
- Remarks:
- with metabolic activation
- Details on test system and experimental conditions:
- ACTIVATION: Phenobarbital (80 mg/kg bw) and β naphthoflavone (100 mg/kg bw) induced rat liver S9 was included in the S9 mix to a final protein concentration of 0.75 mg/ml. Cofactors were added to the following concentrations: 8 mM MgCl2; 33 mM KCl; 5 mM Glucose-6-phosphate; 5 mM NADP.
METHOD OF APPLICATION: in medium;
DURATION
- Exposure duration: 4 hours (Experiment I, +/- MA, Experiment II +MA); 20 hours (Experiment II -MA).
- Expression time (cells in growth medium): 20 hours (Experiment I +/- MA and Experiment II +MA).
SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): Giemsa
NUMBER OF REPLICATIONS: Experiments I and II: Stock cultures in exponential growth were seeded into Quadriperm dishes containing at four slides. Two days after seeding the culture medium was replaced with test item suspension (with S9 mix as appropriate). The slides were divided into sets of two and at least one slide from each set was counted. The experiment was repeated. In experiment III duplicate cultures were treated at each concentration and 100 metaphases were scored per culture.
NUMBER OF CELLS EVALUATED: At least 200 well spread metaphases (100 per slide), containing 22+/- 1 centromeres, per concentration and validity controls were scored for cytogenetic damage.
NUMBER OF CELLS EVALUATED: At least 200 well spread metaphases (100 per slide in experiments I and II, 100 per culture in experiment III), containing 22+/- 1 centromeres, per concentration and validity controls were scored for cytogenetic damage.
DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; relative cell density
OTHER EXAMINATIONS:
- Determination of polyploidy: yes - Evaluation criteria:
- A positive result is determined by: a clear and dose-related increase in the number of cells with aberrations; a biologically relevant response for at least one of the dose groups, which is higher than the laboratory negative control range (0.0% - 4.0% aberrant cells)
- Species / strain:
- Chinese hamster lung fibroblasts (V79)
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Remarks:
- increased percentage of cells with aberrations, not dose dependent or reproducible
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- Remarks:
- some reduction in Mitotic index observed at limit concentration
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- valid
- Positive controls validity:
- valid
- Conclusions:
- Dodecamethylpentasiloxane has been tested according to OECD 473 and in compliance with GLP. An increase in the number of aberrations was observed in the second experiment with metabolic activation but the response was not clearly dose related or reproducible. In a third experiment with metabolic activation there was no increase in the number of aberrations. Therefore dodecamethylpentasiloxane was considered to be non-clastogenic under the conditions of the test.
Referenceopen allclose all
Table 1a Dose range finding test revertants per plate (mean of 2 plates)
Concentration µg/plate |
TA 100 |
TA 1535 |
E. coli WP2 uvrA |
||||||
-MA |
+MA |
Cytotoxic |
-MA |
+MA |
Cytotoxic |
-MA |
+MA |
Cytotoxic |
|
0* |
135 |
141 |
no |
15 |
15 |
no |
42 |
48 |
no |
50 |
123 |
129 |
no |
11 |
16 |
no |
43 |
46 |
no |
100 |
121 |
127 |
no |
15 |
19 |
no |
43 |
50 |
no |
200 |
132 |
125 |
no |
10 |
16 |
no |
47 |
56 |
no |
500 |
127 |
121 |
no |
14 |
16 |
no |
44 |
51 |
no |
1000 |
118 |
117 |
no |
13 |
19 |
no |
47 |
53 |
no |
2000 |
123 |
127 |
no |
13 |
19 |
no |
46 |
50 |
no |
5000 |
129 |
108 |
no |
9 |
19 |
no |
39 |
49 |
no |
10000 |
123 |
123 |
no |
13 |
20 |
no |
52 |
53 |
no |
Positive control |
539 |
1026 |
- |
420 |
306 |
- |
508 |
457 |
- |
* Solvent control with acetone, mean of three plates
Table 1b Dose range finding test revertants per plate (mean of 2 plates)
Concentration µg/plate |
TA 98 |
TA 1537 |
||||
-MA |
+MA |
Cytotoxic |
-MA |
+MA |
Cytotoxic |
|
0* |
27 |
31 |
no |
11 |
19 |
no |
50 |
26 |
29 |
no |
8 |
18 |
no |
100 |
28 |
31 |
no |
8 |
16 |
no |
200 |
27 |
33 |
no |
10 |
19 |
no |
500 |
33 |
27 |
no |
6 |
19 |
no |
1000 |
29 |
31 |
no |
10 |
17 |
no |
2000 |
24 |
32 |
no |
11 |
13 |
no |
5000 |
31 |
33 |
no |
11 |
20 |
no |
10000 |
32 |
32 |
no |
9 |
12 |
no |
Positive control |
621 |
301 |
- |
1581 |
203 |
- |
* Solvent control with acetone, mean of three plates
Table 2a Main test revertants per plate (mean of 2 plates)
Concentration µg/plate |
TA 100 |
TA 1535 |
E. coli WP2 uvrA |
||||||
-MA |
+MA |
Cytotoxic |
-MA |
+MA |
Cytotoxic |
-MA |
+MA |
Cytotoxic |
|
0* |
128 |
133 |
no |
16 |
17 |
no |
46 |
52 |
no |
313 |
122 |
128 |
no |
14 |
11 |
no |
50 |
46 |
no |
625 |
129 |
129 |
no |
13 |
12 |
no |
43 |
48 |
no |
1250 |
140 |
125 |
no |
16 |
15 |
no |
42 |
48 |
no |
2500 |
124 |
121 |
no |
11 |
13 |
no |
38 |
49 |
no |
5000 |
137 |
127 |
no |
13 |
14 |
no |
41 |
51 |
no |
10000 |
144 |
133 |
no |
13 |
16 |
no |
40 |
50 |
no |
Positive control |
645 |
1042 |
- |
445 |
273 |
- |
547 |
492 |
- |
* Solvent control with acetone, mean of three plates
Table 2b Main test revertants per plate (mean of 2 plates)
Concentration µg/plate |
TA 98 |
TA 1537 |
||||
-MA |
+MA |
Cytotoxic |
-MA |
+MA |
Cytotoxic |
|
0* |
25 |
35 |
no |
11 |
17 |
no |
313 |
24 |
33 |
no |
10 |
13 |
no |
625 |
24 |
32 |
no |
10 |
15 |
no |
1250 |
26 |
31 |
no |
12 |
14 |
no |
2500 |
30 |
34 |
no |
10 |
15 |
no |
5000 |
22 |
40 |
no |
10 |
10 |
no |
10000 |
29 |
40 |
no |
13 |
14 |
no |
Positive control |
627 |
318 |
- |
1303 |
233 |
- |
* Solvent control with acetone, mean of three plates
No treatment related increase in the percentage of cells with aberrations was observed with or without activation. No treatment-related polyploidy was observed.
Table 2: Results of chromosome analysis - without activation (% from total count from 2 cultures, 200 cells counted)
Treatment |
Exposure time (h) |
Concentration (µg/ml) |
% polyploid cells |
% cells with aberrations inc gaps |
% cells with aberrations not inc gaps |
Judgement |
Solvent* |
24 |
0 |
0 |
1 |
0.5 |
- |
48 |
0 |
0 |
2 |
0.5 |
- |
|
Test substance |
24 |
31.25 |
0 |
0 |
0 |
- |
62.5 |
0 |
1 |
1 |
- |
||
125 |
1 |
1.5 |
1.5 |
- |
||
48 |
31.25 |
0 |
0 |
0 |
- |
|
62.5 |
0 |
1 |
1 |
- |
||
125 |
0 |
1.5 |
1.5 |
- |
||
Positive control |
24 |
0.05 |
0 |
51.5 |
50.0 |
+++ |
48 |
0.05 |
0 |
67.0 |
65.0 |
+++ |
*0.5% methylcellulose
Table 3: Results of chromosome analysis - with activation, 6 h exposure (% from total count from 2 cultures, 200 cells counted)
Treatment |
S9 mix |
Concentration (µg/ml) |
% polyploid cells |
% cells with aberrations inc gaps |
% cells with aberrations not inc gaps |
Judgement |
Solvent* |
- |
0 |
0.5 |
0 |
0 |
- |
+ |
0 |
0.5 |
1 |
0.5 |
- |
|
Test substance |
_ |
100 |
0.5 |
2 |
1 |
- |
200* |
Toxic |
- |
||||
400* |
Toxic |
- |
||||
+ |
100 |
1 |
0.5 |
0.5 |
- |
|
200* |
1 |
1 |
1 |
- |
||
400* |
0 |
2.5 |
1.5 |
- |
||
Positive control |
- |
10 |
0.5 |
0.5 |
0.5 |
+++ |
+ |
10 |
0 |
28.5 |
28.5 |
+++ |
|
* precipitate
**0.5% methylcellulose
Table 1 Summary of mouse lymphoma mutagenicity results
| Test substance concentration µl/ml | Activation | Relative growth % | Mutant frequency x 10E-06 |
| Solvent control | -MA | 100 | 23.7 |
| Negative control | -MA | 87.7 | 17.2 |
| Positive control | -MA | 20.3 | 515.5 |
| 0.0125 | -MA | 86.8 | 18.5 |
| 0.025 | -MA | 73.1 | 15.8 |
| 0.05 | -MA | 92.3 | 22.3 |
| 0.1 | -MA | 62.0 | 9.5 |
| 0.2 | -MA | 29.5 | 28.1 |
| Solvent control | +MA | 100 | 29.9 |
| Negative control | +MA | 94.9 | 23.1 |
| Positive control | +MA | 25.1 | 196.0 |
| 0.0125 | +MA | 90.4 | 42.1 |
| 0.025 | +MA | 68.4 | 26.3 |
| 0.05 | +MA | 72.5 | 40.3 |
| 0.1 | +MA | 90.4 | 21.1 |
| 0.2 | +MA | 0.1 | 50.7 |
Plate incorporation – average number of revertants per plate (mean of 2 plates).
Experiment 1
Treatment µg/plate |
TA98 |
TA100 |
TA1535 |
TA1537 |
WP2 uvrA |
|||||
-S9 |
+S9 |
-S9 |
+S9 |
-S9 |
+S9 |
-S9 |
+S9 |
-S9 |
+S9 |
|
Solvent control |
15 |
13 |
147 |
164 |
16 |
13 |
4 |
8 |
21 |
18 |
1.5 |
17 |
13 |
160 |
147 |
18 |
12 |
6 |
6 |
18 |
18 |
5.0 |
16 |
14 |
164 |
175 |
19 |
9 |
1 |
8 |
22 |
24 |
15 |
16 |
17 |
140 |
120 |
15 |
11 |
8 |
4 |
19 |
14 |
50 |
13 |
14 |
177 |
156 |
17 |
13 |
6 |
5 |
19 |
21 |
150 |
15 |
18 |
155 |
156 |
22 |
12 |
7 |
6 |
24 |
24 |
500 |
12 |
15 |
172 |
171 |
15 |
12 |
8 |
9 |
24 |
18 |
1500 |
14 |
17 |
149 |
153 |
11 |
7 |
4 |
9 |
23 |
20 |
5000 |
14 |
16 |
179 |
175 |
15 |
9 |
7 |
5 |
21 |
21 |
Positive control |
144 |
454 |
540 |
553 |
369 |
121 |
923 |
131 |
166 |
242 |
Plate incorporation – average number of revertants per plate (mean of 3 plates).
Experiment 2
Treatment µg/plate |
TA98 |
TA100 |
TA1535 |
TA1537 |
WP2 uvrA |
|||||
-S9 |
+S9 |
-S9 |
+S9 |
-S9 |
+S9 |
-S9 |
+S9 |
-S9 |
+S9 |
|
Solvent control |
31 |
17 |
183 |
184 |
20 |
17 |
10 |
8 |
23 |
23 |
50 |
18 |
18 |
189 |
173 |
16 |
16 |
6 |
10 |
21 |
19 |
150 |
28 |
16 |
199 |
172 |
16 |
18 |
11 |
11 |
27 |
24 |
500 |
24 |
12 |
171 |
180 |
12 |
18 |
11 |
7 |
25 |
20 |
1500 |
26 |
17 |
189 |
193 |
18 |
16 |
6 |
10 |
22 |
25 |
5000 |
28 |
19 |
167 |
198 |
16 |
20 |
6 |
10 |
20 |
23 |
Positive control |
194 |
666 |
607 |
660 |
436 |
125 |
1154 |
185 |
127 |
278 |
Summary table of cytogenetic analysis of CHO cells in the absence and presence of metabolic activation
Treatment µg/ml |
S9 Activation |
Treatment time |
Mean mitotic index (1000 cells) |
Cells scored (total no. metaphases) |
Mean aberrations per cell |
Cells with aberrations |
|
Numerical (%) |
Structural (%) |
||||||
Solvent control |
- |
4 |
11.2 |
200 |
0.000 |
0.0 |
0.0 |
2.5 |
- |
4 |
9.9 |
200 |
0.005 |
0.0 |
0.5 |
5 |
- |
4 |
9.8 |
200 |
0.000 |
0.5 |
0.0 |
12.5 |
- |
4 |
9.3 |
200 |
0.000 |
0.0 |
0.0 |
Positive control |
- |
4 |
5.2 |
200 |
0.370 |
0.0 |
20.0 |
|
|
|
|
|
|
|
|
Solvent control |
+ |
4 |
10.9 |
200 |
0.005 |
0.5 |
0.5 |
10 |
+ |
4 |
10.5 |
200 |
0.000 |
0.5 |
0.0 |
20 |
+ |
4 |
10.4 |
200 |
0.000 |
0.0 |
0.0 |
75 |
+ |
4 |
10.4 |
200 |
0.000 |
0.5 |
0.0 |
Positive control |
+ |
4 |
3.3 |
200 |
0.350 |
1.5 |
18.0 |
|
|
|
|
|
|
|
|
Solvent control |
- |
20 |
10.9 |
200 |
0.000 |
0.0 |
0.0 |
5 |
- |
20 |
8.9 |
200 |
0.005 |
0.0 |
0.5 |
10 |
- |
20 |
8.9 |
200 |
0.005 |
0.5 |
0.5 |
15 |
- |
20 |
5.5 |
200 |
0.000 |
0.0 |
0.0 |
Positive control |
- |
20 |
7.0 |
200 |
0.300 |
1.0 |
18.0 |
|
|
|
|
|
|
|
|
Table 2a: Toxicity and mutagenicity assay - plate incorporation (mean of 2 plates)
|
TA98 |
TA100 |
TA1535 |
||||||
Conc. |
— MA |
+ MA |
Cytotoxic |
— MA |
+ MA |
Cytotoxic |
— MA |
+ MA |
Cytotoxic |
0* |
26 |
22 |
No |
161 |
145 |
No |
25 |
25 |
No |
1.5 |
23 |
24 |
No |
130 |
134 |
No |
26 |
20 |
No |
5 |
17 |
22 |
No |
126 |
152 |
No |
22 |
17 |
No |
15 |
15 |
25 |
No |
107 |
125 |
No |
16 |
23 |
No |
50 |
14 |
27 |
No |
108 |
128 |
No |
17 |
29 |
No |
150 |
17 |
24 |
No |
124 |
153 |
No |
24 |
18 |
No |
500 |
23 |
23 |
No |
133 |
148 |
No |
21 |
21 |
No |
1500 |
16 |
20 |
No |
115 |
129 |
No |
27 |
20 |
No |
5000 |
21 |
20 |
No |
135 |
128 |
No |
25 |
18 |
No |
Positive Control |
173 |
488 |
No |
557 |
565 |
No |
342 |
78 |
No |
*solvent control with ethanol
Table 2b: Toxicity and mutagenicity assay - plate incorporation (mean of 2 plates)
|
TA1537 |
WP2 uvrA |
||||
Conc. |
— MA |
+ MA |
Cytotoxic |
— MA |
+ MA |
Cytotoxic |
0* |
11 |
9 |
No |
28 |
13 |
No |
1.5 |
8 |
8 |
No |
17 |
25 |
No |
5 |
8 |
8 |
No |
22 |
19 |
No |
15 |
7 |
8 |
No |
27 |
17 |
No |
50 |
6 |
5 |
No |
20 |
19 |
No |
150 |
7 |
8 |
No |
22 |
24 |
No |
500 |
7 |
7 |
No |
16 |
24 |
No |
1500 |
9 |
6 |
No |
18 |
17 |
No |
5000 |
8 |
10 |
No |
22 |
17 |
No |
Positive Control |
871 |
62 |
No |
141 |
203 |
No |
*solvent control with ethanol
Table 3: Experiment 2 - preincubation Number of revertants per plate (mean of 3 plates)
|
TA98 |
TA100 |
TA1535 |
||||||
Conc. |
— MA |
+ MA |
Cytotoxic |
— MA |
+ MA |
Cytotoxic |
— MA |
+ MA |
Cytotoxic |
0* |
18 |
24 |
No |
84 |
84 |
No |
16 |
21 |
No |
50 |
15 |
19 |
No |
80 |
72 |
No |
17 |
20 |
No |
150 |
15 |
26 |
No |
51 |
97 |
No |
15 |
19 |
No |
500 |
17 |
21 |
No |
78 |
81 |
No |
19 |
24 |
No |
1500 |
23 |
25 |
No |
67 |
90 |
No |
17 |
24 |
No |
5000 |
15 |
24 |
No |
80 |
103 |
No |
20 |
21 |
No |
Positive control |
96 |
124 |
No |
283 |
279 |
No |
184 |
64 |
No |
*solvent control with ethanol
Table 3: Experiment 2 - preincubation Number of revertants per plate (mean of 3 plates)
|
TA1537 |
WP2 uvrA |
||||
Conc. |
— MA |
+ MA |
Cytotoxic |
— MA |
+ MA |
Cytotoxic |
0* |
9 |
9 |
No |
25 |
20 |
No |
50 |
7 |
7 |
No |
18 |
26 |
No |
150 |
5 |
9 |
No |
23 |
21 |
No |
500 |
8 |
5 |
No |
20 |
16 |
No |
1500 |
7 |
3 |
No |
21 |
18 |
No |
5000 |
8 |
7 |
No |
20 |
17 |
No |
Positive control |
505 |
29 |
No |
124 |
104 |
No |
*solvent control with ethanol
Table 1 Preliminary toxicity test
Concentration (μg/ml)
|
% RSG (-S9) 4-Hour Exposure
|
% RSG (+S9) 4-Hour Exposure
|
% RSG (-S9) 24-Hour Exposure
|
0 |
100 |
100 |
100 |
12.14 |
74 |
96 |
72 |
24.27 |
90 |
96 |
26 |
48.55 |
83 |
84 |
0 |
97.09 |
100 |
68 |
0 |
194.19 |
95 |
82 |
1 |
388.38 |
94 |
102 |
1 |
776.75 |
108 |
98 |
1 |
1553.5 |
100 |
102 |
4 |
3107 |
97 |
82 |
39 |
%RSG= Relative Suspension Growth
Table 2 Summary of results from main experiment, 4 h exposure
Treatment (μg/ml)
|
4-Hours-S-9 |
Treatment (μg/ml)
|
4-Hours+S-9
|
||||
%RSG |
RTG |
MF |
%RSG |
RTG |
MF |
||
0 |
100 |
1.00 |
89.99 |
0 |
100 |
1.00 |
114.53 |
12.5 |
112 |
1.29 |
89.46 |
12.5 |
113 |
1.04 |
91.57 |
25 |
111 |
1.28 |
82.23 |
25 |
106 |
1.20 |
95.58 |
50 |
121 |
1.42 |
89.78 |
50 |
102 |
1.05 |
101.72 |
100 P |
110 |
1.28 |
79.77 |
100 |
105 |
1.09 |
93.79 |
150 P |
109 |
1.28 |
86.92 |
150 P |
104 |
1.10 |
88.74 |
200 P |
122 |
1.38 |
86.12 |
200 P |
106 |
1.17 |
98.22 |
Linear trend NS |
Linear trend NS |
||||||
Positive control |
94 |
0.81 |
710.52 |
2 |
65 |
0.29 |
935.61 |
P Precipitate observed at the end of the exposure period.
* Not plated for viability or 5-TFT resistance
%RSG = Relative Suspension Growth
RTG = Relative Total Growth
MF = 5-TFT resistant mutants/106 viable cells 2 days after treatment
Table 3 Summary of results from main experiment, 24 h exposure
Treatment (μg/ml)
|
24-Hours-S-9 |
||
%RSG |
RTG |
MF |
|
0 |
100 |
1.00 |
96.68 |
1.56 * |
109 |
|
|
3.13 |
102 |
0.95 |
108.38 |
6.25 |
101 |
1.29 |
76.85 |
12.5 |
104 |
1.21 |
113.47 |
18.75 |
89 |
1.02 |
93.93 |
25 |
59 |
0.69 |
89.82 |
37.5 |
16 |
0.14 |
141.03 |
50 * |
9 |
|
|
Linear trend NS |
|||
Positive control |
92 |
0.69 |
992.94 |
* Not plated for viability or 5-TFT resistance
%RSG = Relative Suspension Growth = [(dose SG x dose Day 0 Factor)/vehicle control SG] x 100
P(0) = number of negative wells/total wells plated
2 day viability %V = (-lnP(0) x 100)/number of cells/well
RCE = Relative Cloning Efficiency = (%V/mean solvent control %V)x100%
RTG = Relative Total Growth = (RCE x RSG)/100%
MF = 5-TFT resistant mutants/106 viable cells 2 days after treatment
Results of chromosome aberration assay
| Concentration mM | Set | cells scored | Chromatid types | Chromosome types | Polyploid cells (mean) | MI % (mean) | mean aberrant cells | ||||||
| b | f | d | ex | if | id | cx | inc gaps | exc gaps | |||||
| Experiment I, without metabolic activation; 4h treatment, 20 h fixation | |||||||||||||
| Negative control | 1 | 100 | 2 | 0 | 0 | 0 | 1 | 0 | 0 | 0.5 | 100 | 3.5 | 3 |
| 2 | 100 | 1 | 0 | 0 | 0 | 0 | 0 | 2 | |||||
| Solvent control | 1 | 100 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0.5 | 100 | 1.5 | 0.5 |
| 2 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |||||
| 2.5 | 1 | 100 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 90 | 2 | 1.5 |
| 2 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | |||||
| 5* | 1 | 100 | 2 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 89 | 5 | 3.5 |
| 2 | 100 | 1 | 0 | 1 | 0 | 0 | 0 | 1 | |||||
| 10 | 1 | 100 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0.5 | 98 | 3.5 | 1.5 |
| 2 | 100 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | |||||
| Positive controls | 1 | 100 | 6 | 0 | 0 | 1 | 0 | 0 | 0 | 0.5 | 72 | 10 | 8 |
| 2 | 100 | 6 | 0 | 1 | 3 | 0 | 0 | 0 | |||||
| Experiment I, with metabolic activation; 4h treatment, 20 h fixation | |||||||||||||
| Negative control | 1 | 100 | 2 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 96 | 3 | 2 |
| 2 | 100 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | |||||
| Solvent control | 1 | 100 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 2.5 | 100 | 1.5 | 1 |
| 2 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | |||||
| 2.5 | 1 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 78 | 1 | 0 |
| 2 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |||||
| 5 | 1 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 85 | 4 | 1.5 |
| 2 | 100 | 3 | 0 | 0 | 1 | 0 | 0 | 0 | |||||
| 10 | 1 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 76 | 1.5 | 1 |
| 2 | 100 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | |||||
| Positive controls | 1 | 100 | 7 | 0 | 0 | 5 | 0 | 0 | 0 | 0.5 | 79 | 10.5 | 10 |
| 2 | 100 | 16 | 0 | 0 | 4 | 0 | 0 | 0 | |||||
| Experiment II, without metabolic activation; 20h treatment, 20 h fixation | |||||||||||||
| Negative control | 1 | 100 | 2 | 1 | 0 | 0 | 1 | 0 | 0 | 0.5 | 111 | 6.5 | 3 |
| 2 | 100 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | |||||
| Solvent control | 1 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 100 | 3.5 | 0.5 |
| 2 | 100 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | |||||
| 0.125 | 1 | 100 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 95 | 5 | 2 |
| 2 | 100 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | |||||
| 7.5 | 1 | 200 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0.5 | 103 | 3.5 | 2.3 |
| 2 | 200 | 5 | 0 | 1 | 0 | 0 | 0 | 0 | |||||
| 10 | 1 | 200 | 4 | 3 | 1 | 2 | 1 | 0 | 0 | 0.75 | 108 | 4.3 | 3.3 |
| 2 | 200 | 2 | 11 | 0 | 0 | 0 | 0 | 0 | |||||
| Positive controls** | 1 | 100 | 9 | 1 | 0 | 2 | 0 | 0 | 1 | 0.5 | 88 | 12.5 | 10.5 |
| 2 | 100 | 4 | 1 | 0 | 6 | 0 | 0 | 0 | |||||
| Experiment II, with metabolic activation; 4h treatment, 20 h fixation | |||||||||||||
| Negative control | 1 | 100 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 96 | 5.5 | 2.5 |
| 2 | 100 | 2 | 0 | 0 | 0 | 0 | 0 | 1 | |||||
| Solvent control | 1 | 100 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 100 | 2.5 | 1 |
| 2 | 100 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |||||
| 4 | 1 | 100 | 7 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 72 | 8.5 | 6 |
| 2 | 100 | 4 | 0 | 0 | 0 | 0 | 0 | 1 | |||||
| 7 | 1 | 200 | 6 | 0 | 0 | 0 | 0 | 0 | 0 | 0.75 | 83 | 5.8 | 3.3 |
| 2 | 200 | 4 | 1 | 2 | 0 | 1 | 0 | 0 | |||||
| 10* | 1 | 200 | 7 | 0 | 0 | 0 | 0 | 0 | 0 | 0.5 | 84 | 6.8 | 4.8 |
| 2 | 200 | 11 | 2 | 0 | 1 | 0 | 0 | 0 | |||||
| Positive controls | 1 | 100 | 5 | 0 | 0 | 9 | 0 | 0 | 0 | 0.5 | 88 | 12.5 | 11 |
| 2 | 100 | 4 | 1 | 0 | 4 | 0 | 0 | 0 | |||||
Experiment III, with metabolic activation; 4h treatment, 20 h fixation |
|||||||||||||
Negative control |
1 |
100 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
69 |
4.0 |
1.0 |
2 |
100 |
4 |
0 |
0 |
1 |
0 |
0 |
0 |
|||||
Solvent control |
1 |
100 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
63 |
2.5 |
1.0 |
2 |
100 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
|||||
2.5 |
1 |
100 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
81 |
3.5 |
1.0 |
2 |
100 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
|||||
5.0 |
1 |
100 |
1 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
75 |
3.0 |
1.5 |
2 |
100 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
|||||
10 |
1 |
100 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
67 |
3.0 |
1.5 |
2 |
100 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
|||||
Positive controls** |
1 |
100 |
4 |
1 |
0 |
1 |
0 |
0 |
0 |
0 |
90 |
9.0 |
7.5 |
2 |
100 |
6 |
0 |
0 |
4 |
0 |
0 |
0 |
|||||
* one cd at this concentration; ** one ma at this concentration; *** one ib at this concentrationb/ib break/isobreak f/if fragment/isofragment d/id deletion/isodeletion ex chromatid exchange cx chromosome exchange cd chromosome deletion ma multiple aberration (>4 events including gaps)
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (negative)
Genetic toxicity in vivo
Description of key information
HMDS was negative for mutagenicity in a rat bone marrow in vivo chromosome aberration assay conducted according to a protocol that is similar to OECD 475 using intraperitoneal administration.
Link to relevant study records
- Endpoint:
- in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 1980-11-26 to 1981-09-28
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- guideline study with acceptable restrictions
- Remarks:
- It was not compliant with GLP.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)
- Deviations:
- yes
- Remarks:
- only male animals used. Number of cells counted for determination of mitotic index not indicated - probably ca. 100, should be 1000
- Principles of method if other than guideline:
- The test was performed according to the Rodent Bone Marrow Cytogenetic Assay as recommended by the Ad Hoc Committee on Chromosome Methodologies in Mutagen Testing (Toxicology and Applied Pharm 22: 269-275, 1972) with modifications per the EPA Gene-Tox Program Cytogenetics Committee (12/3 to 12/5, 1980, Washington D.C.).
- GLP compliance:
- not specified
- Type of assay:
- chromosome aberration assay
- Species:
- rat
- Strain:
- Sprague-Dawley
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Age at study initiation: 14 - 16 weeks
- Weight at study initiation: 250 - 280 g for range finding. 290 - 430 g for cytogenetic study
- Housing: 6 per cage
- Diet (e.g. ad libitum): Charles River Agway
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 68 ± 3 F
- Humidity (%): approx 50 - Route of administration:
- intraperitoneal
- Vehicle:
- - Vehicle(s)/solvent(s) used: paraffin oil
- Lot/batch no. (if required): A7M02
- Purity: Laboratory Grade - Duration of treatment / exposure:
- single treatment
- Frequency of treatment:
- Single IP injection
- Post exposure period:
- 6, 24 and 48 hours
- Remarks:
- Doses / Concentrations:
255, 515 and 1030 mg/kg
Basis:
nominal conc. - No. of animals per sex per dose:
- 5 males/dose
- Control animals:
- yes, concurrent vehicle
- Positive control(s):
- cyclophosphamide, positive control agent, was included in the 24-hour group.
- Route of administration: IP Injection
- Doses / concentrations: 22 mg/kg bw - Tissues and cell types examined:
- Bone marrow from femur
- Details of tissue and slide preparation:
- CRITERIA FOR DOSE SELECTION: Based on two range finding studies conducted to determine the maximum dose the animals could tolerate.
Range finding studies: Range finding study 1: Animals Injected intraperitoneally with 1676, 504, 168 and 50 mg/kg and observed once a day for 7 days for signs of toxicity. Range finding study 2: 10 animals injected with 3911, 1825, 521, 183 and 52 mg/kg. In main study animals were sacrificed at 6, 24 and 48 hours
DETAILS OF SLIDE PREPARATION: Approximately 4 slides were prepared for each animal. The chromosomes were prepared by standard methods and Giemsa stained.
TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields):
6h group: Stock solution of 321 mg/ml; volumes injected were 1.0, 0.5 and 0.25 ml, resulting in the following doses calculated from body weight: 1030 mg/kg +/- 3.2%; 515 mg/kg +/- 5.6%; 255 mg/kg +/- 1.2%
24 hour group: animals were injected with 1.0 or 0.5 ml of 321 mg/ml stock solution, or 1.0 ml of 91 mg/ml stock solution, resulting in the following doses calculated from body weight: 1030 mg/kg +/- 0.8%; 515 mg/kg +/- 5.6%; 255 mg/kg +/- 3.1%
48 hour group: animals were injected with 1.0 or 0.45 ml of 426 mg/ml stock solution, or 1 ml of 102 mg/ml stock solution. This resulted in the following doses calculated from body weight: 1030 mg/kg +/- 3.1%; 515 mg/kg +/- 9.3%; 255 mg/kg +/- 2.4%
METHOD OF ANALYSIS: metaphase cells analysed by projecting the negatives with a darkroom enlarger onto a white counter
OTHER: - Evaluation criteria:
- In general, a minimum of 100 metaphase cells from each animal were scored for incidence of chromosomal aberrations.
- Statistics:
- Statistical methods: Chi2 test for comparison of expected and observed distribution of the number of breaks; Wilcoxon test was used as a nonparametric test.
- Sex:
- male
- Genotoxicity:
- negative
- Remarks:
- on mitotic index
- Toxicity:
- no effects
- Vehicle controls validity:
- valid
- Negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Additional information on results:
- RESULTS OF RANGE-FINDING STUDY
- Dose range: Exp 1: 1676, 504, 168, 50 mg/kg. Exp 2: 3911, 1825, 521, 183, 52 mg/kg
- Clinical signs of toxicity in test animals: No deaths observed in initial study. In second study 3 of 10 animals dosed with 3911 mg/kg died, while all the other animals survived till terminal sacrifice.
- Harvest times: 7 days exp 1, 14 days exp 2.
- High dose with and without activation: 1676 exp 1, 3911 exp 2
RESULTS OF DEFINITIVE STUDY
See table 1 - Conclusions:
- Hexamethyldisiloxane has been tested for the induction of chromosome aberrations in rat bone marrow cells in a valid study conducted according to a protocol that is similar to OECD 475. There was no evidence of induction of chromosomal damage in the bone marrow cells of rats following intraperitoneal injection. 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.
Reference
Negative controls: frequencies of breaks were 0.54%, 2.49% and 1.47% at sacrifice at 6, 24 and 48 hours respectively.
Table 1:Results of chromosome analysis in rat bone marrow cells: test substance (total number of aberrations observed)
|
Low dose (255 mg/kg bw) |
Mid dose (515 mg/kg bw) |
High dose (1030 mg/kg bw) |
|||||||
Sampling time (h) |
6 |
24 |
48 |
6 |
24 |
48 |
6 |
24 |
48 |
|
Number of cells evaluated |
500 approx |
500 approx |
500 approx |
500 approx |
500 approx |
500 approx |
500 approx |
500 approx |
500 approx |
|
Toxicity,specify effects |
|
|
|
|
|
|
|
|
|
|
Chromosome aberrations |
Gaps |
6 |
11 |
3 |
3 |
6 |
25 |
2 |
12 |
14 |
Breaks |
5 |
2 |
9 |
10 |
15 |
6 |
5 |
6 |
7 |
|
Other aberrations |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
|
Mitotic index (% range) |
2 – 5 |
2 - 5 |
1 - 4 |
2 - 4 |
2 - 5 |
4 - 7 |
1 - 6 |
3 - 5 |
2 - 5 |
|
Polyploidy |
N.R |
N.R |
N.R |
N.R |
N.R |
N.R |
N.R |
N.R |
N.R |
|
Endo reduplication |
N.R |
N.R |
N.R |
N.R |
N.R |
N.R |
N.R |
N.R |
N.R |
|
N.R = Not Reported
Table 2 Results of chromosome analysis in rat bone marrow cells: control substances (total number of aberrations observed)
|
Vehicle control |
Positive control |
|||
Sampling time (h) |
6 |
24 |
48 |
48 |
|
Number of cells evaluated |
500 approx |
450 approx |
500 approx |
250 approx |
|
Chromosome aberrations |
Gaps |
6 |
19 |
15 |
ND |
|
Breaks |
3 |
12 |
8 |
145 |
|
Other aberrations |
0 |
0 |
0 |
4 quad, 6 tri, 5 del |
Mitotic index (% range) |
|
2-7 |
1-4 |
3-4 |
2-4 |
N.R = Not Reported
quad = quadriradial tri =
triradial del = deletion
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (negative)
Additional information
There are no available genetic toxicity studies for the registered substance "Reaction Mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane". Therefore, data have been read-across from its four constituents:
1) HMDS: hexamethyldisiloxane (CAS 107-46-0)
2) L3: octamethyltrisiloxane (CAS 107-51-7)
3) L4: decamethyltetrasiloxane (CAS 141-62-8)
4) L5: dodecamethylpentasiloxane (CAS 141-63-9
In vitro
Bacterial mutagenicity:
HMDS has been tested according to a Japanese guideline that is similar to OECD 471 and in compliance with GLP, using the pre-incubation method (Shin Etsu, 1994). The study is considered to be reliability 2 as duplicate not triplicate plates were used. No evidence of test-substance induced increase in the number of revertants was observed in Salmonella typhimurium strains TA1535, TA1537, TA98, TA100 or E.coli WP2 uvrA, with or without metabolic activation, up to a concentration exceeding current limit concentrations, in either the dose finding test or the main assay. Appropriate solvent, positive and sterility 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 substance. The key study is supported by a number of older, less reliable studies all of which reported negative results.
L3 has been tested for mutagenicity to bacteria in a study which was conducted according to OECD 471, and in compliance with GLP (Wagner, 2008). No evidence of a test substance related increase in the number of revertants was observed with or without activation in the initial or the repeat experiments with Salmonella typhimurium strains TA 98, 100, 1535, 1537 and E.coli WP2 uvrA. Appropriate positive and solvent controls were tested and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.
L4 has been tested in a reliable study conducted according to OECD 471 1997 and under GLP up to limit concentrations (Wagner, 2005). No increase in the number of revertants was observed at any concentration with and without metabolic activation in Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and E. coli WP2 uvrA in either the initial plate incorporation assay or the independent repeat experiment which used the pre-incubation method. It is considered that the test substance was negative for mutagenicity to bacteria under the conditions of the test.
Mammalian cytogenicity:
HMDS has been tested under GLP in a valid Japanese guideline study according to a protocol that is similar to OECD TG 473 (Shin Etsu, 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.
Information on the potential of L3 for clastogenicity to mammalian cells is available from a reliable in vitro cytogenetic assay conducted according to OECD TG 473 and under GLP (Madraymootoo and Rao (2008)). The test substance did not induce statistically and biologically significant increases in the chromosomal aberration frequency in CHO cells. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for the induction of chromosome aberrations in vitro (is not clastogenic) under the conditions of the test.
L5 has been tested according to OECD 473 and in compliance with GLP (Bioservice, 2013). The final draft report was available to the reviewer. An increase in the number of aberrations was observed in the second experiment after 4 hours exposure with metabolic activation but the response was not clearly dose related or reproducible. In a third experiment, following a 4 hour exposure with metabolic activation, there was no increase in the number of aberrations. Appropriate solvent and positive controls were included and gave expected results. It is concluded that dodecamethylpentasiloxane is non-clastogenic in Chinese hamster V79 cells under the conditions of the test.
Mammalian mutagenicity:
HMDS has been tested for mutagenicity in L5178Y cells in a reliability 2 study conducted according to a protocol that is similar to OECD TG 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.
L4 has been tested according to OECD TG 476 and under GLP conditions for mutagenicity to mouse lymphoma L5178Y cells up to cytotoxic concentrations (Flanders L (2010)). No increase in mutant frequency was detected at any concentration after 4h exposure with and without metabolic activation and 24 h exposure without metabolic activation. Appropriate solvent and positive controls were included and gave expected results. It is concluded that the test substance is negative for the induction of mutations in L5178Y cells under the conditions of the test.
In vivo
The conclusion reached from the in vitro results is confirmed by the negative result obtained when HMDS was tested in vivo in a rat bone marrow chromosome aberration assay conducted according to a protocol that is similar to OECD 475 using intraperitoneal administration. The test substance was considered to be non-clastogenic (negative for the induction of chromosome aberrations) in rat bone marrow cells under the conditions of the test (Dow Corning Corporation, 1982). In addition, HMDS, L3, L4 and L5 do not include structural alerts for genetic toxicity. It is concluded that the available data does not indicate a potential for germ cell mutagenicity.
Read-across from consituents justification
A detailed read-across explanation is available in Section 7.5.
Reaction Mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane (EC No 946-797-7) belongs to the structural class of siloxanes. All the substances have high log Kow (increasing with increasing chain length) and low water solubility. In vivo and in vitro genetic toxicity data are available for a number of these substances.
The available studies for the linear siloxanes from this analogue group, as well as key physicochemical properties, are summarised in the table below. There is no evidence from any of the available studies that the substances in this group have any potential for genetic toxicity or mutagenicity. It is therefore valid to read-across the lack of genotoxic potential between the members of the group where there are data gaps. The most recent and reliable studies for the substance’s constituents were chosen for weight of evidence.
Table: Summary of key mutagenicity data for linear siloxanes
CAS |
Name |
Bacterial Mutagenicity |
In Vitro Mammalian Cytogenicity |
In Vitro Mammalian Mutagenicity |
In Vivo Genotox |
107-46-0 |
HMDS |
Negative (Hita Laboratories, 1994) |
Negative (Hita Laboratories, 1995) |
Negative (Litton Bionetics, 1978a) |
Negative in chromosome aberration assay (Dow Corning Corporation, (1982)
|
107-51-7 |
L3 |
Negative (BioReliance, 2008) |
Negative (BioReliance, 2008) |
No data |
No data |
141-62-8 |
L4 |
Negative (BioReliance, 2005) |
No data |
Negative (Harlan, 2010) |
No data |
141-63-9 |
L5 |
No data |
Negative (Bioservice, 2014) |
No data |
No data |
Justification for classification or non-classification
Based on the available data for Reaction Mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane constituents, no classification is required for genetic toxicity 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.
