Triethyl borate

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Acceptable, study with sufficient detailed documentation to demonstrate that study meets basic scientific principles and contains enough detail to be able to judge the results reliable as a contribution to the understanding of the genotoxic potential of this substance.

Data source

Reference

Reference Type:

publication

Title:

Mouse lymphoma L5178Y thymidine kinase locus assay of 50 compounds.

Author:

Wangenheim, J. and Bolcsfoldi, G.

Year:

1988

Bibliographic source:

Mutagen. 3(3):193-205.

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Remarks:

, no significant deviations noted

Principles of method if other than guideline:

Method: other: Clive et al. (Muta Res, 59, 61, 1979) with some minor modifications to reduce experiment time and plating efficiency. Study examined a large number of chemicals.

GLP compliance:

not specified

Type of assay:

mammalian cell gene mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Ethanol

EC Number:

200-578-6

EC Name:

Ethanol

Cas Number:

64-17-5

Molecular formula:

C2H6O

IUPAC Name:

ethanol

Details on test material:

- Supplier AB Svenska Sprit (Sweden)
- Purity: highest available (not specified)

Method

Target gene:

TK forward mutation

Species / strain

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: Fisher's medium with 10% horse serum, adjusted to pH 7.2
- Source: Boroughs Welcome Co, Research Triangle Park, NC, USA
- Periodically "cleansed" against high spontaneous background: yes by treatement with thymidine, hypoxanthine, methotrexate and glycine

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

Liver S9 from Sprague-Dawley rat livers, animals pre-treated with Aroclor 1254.

Test concentrations with justification for top dose:

0.092, 0.184, 0.369, 0.553, 0.738 mol/l without activation; 0.414, 0.465 and 0.517 mol/l with activation

Controls

Controls 1

Untreated negative controls:

yes

Negative solvent / vehicle controls:

not specified

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Controls 2

Positive control substance:

cyclophosphamide

Controls 3

Positive control substance:

4-nitroquinoline-N-oxide

Controls 4

Positive control substance:

2-nitrofluorene

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 4 hours
- Expression time (cells in growth medium): 48 hours
- Selection time (if incubation with a selection agent): no data
- Fixation time (start of exposure up to fixation or harvest of cells):

SELECTION AGENT (mutation assays): trifluorothymidine

NUMBER OF REPLICATIONS: 3 per dose level but 6 for negative control.

DETERMINATION OF CYTOTOXICITY
- Mitotic index: Not strictly applicable. Total growth cf. controls were 88, 84, 53, 34 and 17% from lowest to highest concentrations in the absence of activation. With activation, total growth was 43, 24, and 6% from lowest to highest concentration.

Evaluation criteria:

Two fold or greater increase in mutation frequency at 10% or greater total growth cf. controls.

Statistics:

Tested for normal distribution and then analysis of variance and 2-tailed Student's t-test against controls.

Results and discussion

Test results

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- None

ADDITIONAL INFORMATION ON CYTOTOXICITY: see table below
- Frequency of reversions etc: Without activation, mutation index values from lowest to highest dose were 1.3, 1.1, 1.2, 1.1 and 1.6. With metabolic activation these values were 1.1, 1.3 and 1.8.
- Dose-effect related observations: No dose-effect related observations were seen.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Only at the maximum concentration, with metabolic activation was total growth <10% control. Without activation, the lowest and highest concentrations of ethanol produced statistically significant increases in mutation frequency.

Without metabolic activation

Concentration (mols/litre)	Total growth	Mutation frequency	Mutation index
0	100%	80, 99	1.0
0.0922	88%	118*	1.3
0.184	84%	94	1.1
0.369	53%	104	1.2
0.553	34%	101	1.1
0.738	17%	140**	1.6

With metabolic activation

Concentration (mols/litre)	Total growth	Mutation frequency	Mutation index
0	100%	63, 46	1.0
0.414	43%	62	1.
0.465	24%	70	1.3
0.517	6%	97**	1.8

*significant, ** highly significant

Rates of spontaneous mutation frequencies in study: without metabolic activation 76 +/-25, with metabolic activation 86 +/-33.

Results are supported by those of Amacher, D., et al. (1980) Mutat. Res. 72:447 -474

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

Ethanol is judged not to have significant mutagenic activity in this system.

Executive summary:

In a mammalian cell mutation study using mouse lymphoma lymphoma cells in the TK forward mutation assay, ethanol was found to be non mutagenic with and without metabolic activation at very high doses up to and including those that cause significant cytotoxicity (typically in the region 0.3 -0.5M.