A mixture of RR and RS isomers of: (2-(2-methoxy-1-methyl)ethoxy)-1-methylethyl acetate; (2-(2-methoxy-2-methyl)ethoxy)-1-methylethyl acetate; (2-(2-methoxy-2-methyl)ethoxy)-2-methylethyl acetate; (2-(2-methoxy-1-methyl)ethoxy)-2-methylethyl acetate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

A bacterial mutagenicity, in vitro Chrom Abs and In vitro mammalian cell mutagenicity assay are available on DPMA

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study.

Qualifier:

according to guideline

Guideline:

other: KIHATSU No 603; Test guidelines for bacterial mutagenic testing, (Notice No 77, 1 September 1988, Ministry of Labour, amended subsequently by Notice No 67, 2 June 1997, and KIHATSU No 413, 2 June 1997)

GLP compliance:

yes

Type of assay:

bacterial gene mutation assay

Target gene:

his-/his+

Species / strain / cell type:

S. typhimurium TA 98

Details on mammalian cell type (if applicable):

- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: not specified in the report
- Periodically "cleansed" against high spontaneous background: not specified in the report

Species / strain / cell type:

S. typhimurium TA 1537

Details on mammalian cell type (if applicable):

- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: not specified in the report
- Periodically "cleansed" against high spontaneous background: not specified in the report

Species / strain / cell type:

S. typhimurium TA 100

Details on mammalian cell type (if applicable):

- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: not specified in the report
- Periodically "cleansed" against high spontaneous background: not specified in the report

Species / strain / cell type:

E. coli WP2 uvr A

Details on mammalian cell type (if applicable):

- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: not specified in the report
- Periodically "cleansed" against high spontaneous background: not specified in the report

Metabolic activation:

with and without

Metabolic activation system:

S-9 metabolic activation system

Test concentrations with justification for top dose:

Dose range-finding study: 0, 19.5, 78.1, 313, 1250, or 5000 ug/plate
Main study: 0, 313, 635, 1250, 2500, or 5000 ug/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: water
- Justification for choice of solvent/vehicle: As DPMA was easily soluble in water, injection water (Lot No. 99J14A) was used as the solvent.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

yes

Positive controls:

yes

Positive control substance:

other: AF-2, 9-aminoacridine, sodium azide and 2-aminoanthracene

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION
- Preincubation period: 20 minutes
- Exposure duration: 48 hours
- Expression time (cells in growth medium): 48 hours

NUMBER OF REPLICATIONS: 2 per concentration

NUMBER OF CELLS EVALUATED: not specified in the report

DETERMINATION OF CYTOTOXICITY
- Method: number of colonies

Frozen stock cultures of Salmonella typhimurium were transferred to nutrient rich broth and incubated at 37°C until reaching a cell density between 1 and 2E9 cells/ml for each of the four tester strains (TA98, TA100, TA1535, & TA1537).

Results were considered positive if the number of colonies exceeded twice background for any of the strains at any dose and if a dose-response relationship was observed in any strain, with or without S-9 activation. In addition the positive response had to be reproducible in a second experiment. Results were considered negative if the revertant counts did not exceed twice background for any tester strain and the negative response was reproducible in a second experiment

Evaluation criteria:

For a test to be considered valid, if each value of positive and negative control plates remained within the standard range calculated from the background data and there was no abnormal finding in the sterility test.
If the treatment plate did not show any growth inhibition caused at least a doubling of mean revertany colonies over the negative control and the reproducible positive results were observed in dose dependent way, it was concluded as a mutagenic activity.

Species / strain:

other: Salmonella typhimurium (strains TA98, TA100, TA1535 and TA1537) and Escherichia coli, strain (WP2uvrA)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: Not toxic at highest concentration.

Remarks on result:

other: strain/cell type: Salmonella typhimurium (strains TA98, TA100, TA1535 and TA1537) and Escherichia coli, strain (WP2uvrA)

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

DPMA did not induce a mutagenic response in any tester strain at any concentration, with or without S-9 metabolic activation and toxicity did not interfere with the assay and negative and positive controls fell within historical control limits

Executive summary:

Test substance, DPMA was tested for mutagenic potential using histidine dependent autotrophic mutants of Salmonella typhimurium, strains TA 98, TA1537, and TA100, and a tryptophan dependent mutant of Escherichia coli, strain WP2uvrA in two independent mutation tests in the presence (with metabolic activity) and absence (without metabolic activity) of liver preparations (S9-mix) by preincubation method.

DPMA dissolved in the distilled water for injection (Japan Pharmacopoeia) up to 5000 μg/plate were tested, and 6 dose levels were separated by 2 of common ratio in the preliminary study. In the definitive study, 5000μg/plate was a highest dose level and then 5 dose levels were selected by 4 of common ratio as set those in the preliminary test.

No evidence of mutagenic activity to show the increases in the reverse mutation colonies exceeding 2 folds of those of negative control value was seen at any dose level off DPMA in either mutation test. The values calculated for the concurrent negative and positive controls of each strain were within the range of the background data.

Under the conditions of the study, it was concluded that DPMA shows no evidence of mutagenic activity in this bacterial system.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

DPMA was negative for genotoxicity in all available studies.

Justification for selection of genetic toxicity endpoint
An OECD guideline, reliability 1 GLP study

Justification for classification or non-classification

All in vitro mutagenicity studies with the test substance were negative, therefore dipropylene glycol methyl ether acetate is not classified for genotoxicity.