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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

The conclusion on genotoxic properties is drawn on reliable in vitro genotoxicity studies of two substance analogues. The rationale to read across the data is attached in Section 13.

Link to relevant study records

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Endpoint:
in vitro gene mutation study in bacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
The rationale to read across the data is attached in Section 13.
Reason / purpose for cross-reference:
read-across source
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
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: No precipitation was observed up to and including the top dose of 5000 µg/plate

RANGE-FINDING/SCREENING STUDIES:
- No toxicity or mutagenicity was observed up to and including the top dose of 5000 µg/plate

COMPARISON WITH HISTORICAL CONTROL DATA:
- The negative and strain-specific positive control values were within our laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.
Conclusions:
In an AMES test, performed according to OECD guideline and GLP principles, TMAC was found not to be mutagenic with or without metabolic activation. The result is read across to TEAH.
Executive summary:

An AMES test was performed according to OECD guideline and GLP principles. All bacterial strains showed negative responses up to 5000 ug/plate, i.e. no significant dose-related increase in the number of revertants with or without metabolic activation was seen. The negative and strain-specific positive control values were within the laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.

Based on the results of this study it is concluded that TMAC is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay with and without metabolic activation. The result is read across to TEAH.

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
The rationale to read across the data is attached in Section 13.
Reason / purpose for cross-reference:
read-across source
Type of assay:
bacterial reverse mutation assay
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:
cytotoxicity
Remarks:
at 1250 ug/plate and above
Vehicle controls validity:
valid
Positive controls validity:
valid
Conclusions:
In an AMES test conducted according to OECD guideline 471 and GLP principles, TMAH was found to be negative for mutagenicity, with or without metabolic activation. The result is read across to TEAH.
Executive summary:

An AMES test was conducted according to OECD guideline 471 and GLP principles. Considerable growth inhibition was observed in all strains treated at the highest concentrations of tetramethylammonium hydroxide. However, no increase in the number of revertant colonies was observed in either strain (S. typhimurium TA98, TA100, TA1535, TA1537, or E.coli WP2 uvrA) treated at any concentrations of tetramethylammonium hydroxide with or without metabolic activation (S9 mix). These results have led to the conclusion that tetramethylammonium hydroxide is negative for mutagenicity in the bacterial reverse mutation assay (Ames test) regardless of metabolic activation. The result is read across to TEAH.

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
The rationale to read across the data is attached in Section 13.
Reason / purpose for cross-reference:
read-across source
Species / strain:
Chinese hamster lung (CHL/IU)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid
Conclusions:
In a chromosomal aberration test Tetramethylammonium was found not to induce polyploidy or other genetic aberrations. The result is read across to TEAH.
Executive summary:

A chromosomal aberration test was conducted according to OECD guideline 473 and GLP principles. Chinese hamster lung (CHL/IU) cells were exposed to 228, 455 or 910 ug/ml with and without metabolic activation. No considerable inhibition of cell growth was observed up to the highest dose. No increase in the number of polyploid cells or cells with structural genetic aberrations were found after treatment with the test substance for 24 hr in the absence of metabolic activation or shortly for 6 hr with the test substance in the presence or absence of metabolic activation. Based on these findings, tetramethylammonium hydroxide was considered negative in the induction of chromosomal aberrations. The result is read across to TEAH.

Endpoint:
in vitro gene mutation study in mammalian cells
Remarks:
T
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
The rationale to read across the data is attached in Section 13.
Reason / purpose for cross-reference:
read-across source
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS:
- Effects of pH: No, pH at highest concentration (1812 μg/ml (= 10 mM)) was 7.9 versus 7.3 in the solvent control.
- Effects of osmolality: No, osmolality at highest concentration (1812 μg/ml (= 10 mM)) was 0.308 Osm/kg versus 0.311 Osm/kg in the solvent control.
- Precipitation: No precipitation in the exposure medium was observed at any concentration.

RANGE-FINDING/SCREENING STUDIES:
- No toxicity was observed up to the precipitating dose levels of 1812 μg/ml in the absence and presence of S9-mix.

COMPARISON WITH HISTORICAL CONTROL DATA:
The spontaneous mutation frequencies in the solvent-treated control cultures were between the minimum and maximum value of the historical control data range and within the acceptability criteria of this assay.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
No toxicity was observed up to and including the highest tested dose level in both experiments in the absence and presence of S9-mix.
Conclusions:
Based on a mouse lymphoma assay conducted according to OECD 476 guideline and GLP principles, it can be concluded that TMAH is not mutagenic in the mouse lymphoma L5178Y test system under the experimental conditions described in this report. The result is read across to TEAH.
Executive summary:

A mouse lymphoma assay was conducted according to OECD 476 guideline and GLP principles. The spontaneous mutation frequencies in the solvent-treated control cultures were between the minimum and maximum value of the historical control data range Positive control chemicals, methyl methane sulfonate and cyclophosphamide induced appropriate responses. In the absence of S9-mix, TMAH did not induce a significant increase in the mutation frequency in the first experiment. This result was confirmed in an independent repeat experiment with modifications in the duration of treatment time. In the presence of 8% v/v S9-mix, TMAH did not induce a significant increase in the mutation frequency in the first experiment. This result was confirmed in an independent repeat experiment with 12% v/v S9 for metabolic activation. It is concluded that TMAH is not mutagenic in the mouse lymphoma L5178Y test system under the experimental conditions described in this report. The result is read across to TEAH.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

An AMES test was conducted with TMAH according to OECD guideline 471 and GLP principles. Considerable growth inhibition was observed in all strains treated at the highest concentrations of tetramethylammonium hydroxide. However, no increase in the number of revertant colonies was observed in either strain (S. typhimurium TA98, TA100, TA1535, TA1537, or E.coli WP2 uvrA) treated at any concentrations of tetramethylammonium hydroxide with or without metabolic activation (S9 mix).These results have led to the conclusion that tetramethylammonium hydroxide is negative for mutagenicity in the bacterial reverse mutation assay (Ames test) regardless of metabolic activation.

A chromosomal aberration test was conducted with TMAH according to OECD guideline 473 and GLP principles. Chinese hamster lung (CHL/IU) cells were exposed to 228, 455 or 910 ug/ml with and without metabolic activation.No considerable inhibition of cell growth was observed up to the highest dose. No increase in the number of polyploid cells or cells with structural genetic aberrations were found after treatment with the test substance for 24 hr in the absence of metabolic activation or shortly for 6 hr with the test substance in the presence or absence of metabolic activation.Based on these findings, tetramethylammonium hydroxide was considered negative in the induction of chromosomal aberrations.

A mouse lymphoma assay was conducted with TMAH according to OECD 476 guideline and GLP principles. The spontaneous mutation frequencies in the solvent-treated control cultures were between the minimum and maximum value of the historical control data range Positive control chemicals, methyl methane sulfonate and cyclophosphamide induced appropriate responses. In the absence of S9-mix, TMAH did not induce a significant increase in the mutation frequency in the first experiment. This result was confirmed in an independent repeat experiment with modifications in the duration of treatment time. In the presence of 8% v/v S9-mix, TMAH did not induce a significant increase in the mutation frequency in the first experiment. This result was confirmed in an independent repeat experiment with 12% v/v S9 for metabolic activation. It is concluded that TMAH is not mutagenic in the mouse lymphoma L5178Y test system under the experimental conditions described in this report.

An AMES test was performed with TMAC according to OECD guideline and GLP principles. All bacterial strains showed negative responses up to 5000 ug/plate, i.e. no significant dose-related increase in the number of revertants with or without metabolic activation was seen. The negative and strain-specific positive control values were within the laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.

Based on the results of this study it is concluded that TMAC is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay with and without metabolic activation.

The rationale to read across these data to TEAH is included in section 13.


Justification for selection of genetic toxicity endpoint
No key study was selected, since several in vitro studies performed with substance analogues TMAH were used.

Short description of key information:
Three in vitro tests were performed with substance analogue TMAH (AMES test, chromosome aberration test and MLA assay). TMAH was shown to be negative with and without metabolic activation in all tests. In an AMES test, TMAC was found not to be mutagenic with or without metabolic activation. All available studies have Klimisch score 2. The rationale to read across these data to TEAH is included in section 13.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available data on substance analogues, TEAH is not classified for genotoxicity according to CLP Regulation (EC) No. 1272/2008.