Isobutyl acetate

Genetic toxicity: in vitro

Administrative data

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:

From 14 AUG 1989 to 08 SEP 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP-study, comparable to guideline study with acceptable restrictions (no information on test substance).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

: no information on test substance

Principles of method if other than guideline:

No guideline stated but study according to Ames et al. (1975), Mutat. Res. 31, 347-364

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Isobutyl acetate

EC Number:

203-745-1

EC Name:

Isobutyl acetate

Cas Number:

110-19-0

Molecular formula:

C6H12O2

IUPAC Name:

isobutyl acetate

Details on test material:

- Name of test material (as cited in study report): C-01360; isobutyl acetate, urethane grade
- Physical state: clear colourless liquid
- Analytical purity: no data ( but as iso-butyl acetate is usually available as high quality / purity, it can probably be assumed that test item purity was high)
- Purity test date: no data
- Lot/batch No.: no data
- Stability under test conditions: no data
- Storage condition of test material: room temperature

Method

Target gene:

his

Species / strain

Species / strain / cell type:

S. typhimurium, other: TA98, TA100, TA1535, TA1537, and TA1538

Details on mammalian cell type (if applicable):

- Properly maintained: yes

Additional strain / cell type characteristics:

other: all strains: rfa - cell wall deficiency, uvrB - deficient DNA excision-repair system, strains TA98 and TA100: presence of pKM101 plasmid (carriing r-factor) - increased sensitivity to some mutagens

Metabolic activation:

with and without

Metabolic activation system:

S-9 mix from the livers of Aroclor 1254 induced (500 mg/kg) male Sprague-Dawley rats.

Test concentrations with justification for top dose:

0, 100, 333, 1000, 3333 and 10000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: no data

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: with S-9 mix: 2-aminoanthracene; without S-9 mix: 2-nitrofluorene (TA98, TA1538), sodium azide (TA100, TA1535), ICR-191 (TA1537)

Remarks:

S-9 preparations were tested for metabolic activity with 7,12-Dimethylbenzanthracene and 2-aminoanthracene

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 h
- Expression time (cells in growth medium): 48 h

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth; toxicity was determined in a preceding-range finding test with tester strain TA100.

OTHER: The integrity of tester strains was checked by testing for rfa wall mutation (sensivity to crystal violet) and for pKM101 plamid r-factor (resistance to ampicillin).

Evaluation criteria:

- To be evaluated as positive, a test substance must cause at least a doubling in the mean revertants per plate of at least one tester strain.
- This increase in the mean number of revertants per plate must be accompanied by a dose response to increasing concentrations of the test substance.
- If the study is to be judged positive solely on the basis of a dose-responsive, less than 3-fold increase on TA1537 or TA1538, the response must be confirmed in a repeat experiment.

Results and discussion

Test results

Species / strain:

S. typhimurium, other: TA98, TA100, TA1535, TA1537, and TA1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

In the range finding test, no cytotoxicity was observed in tester strain TA100 up to the highest concentration tested (10000µg/plate).

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING/SCREENING STUDIES:
- A range-finding test was performed using tester strain TA100 and 10 evenly spaced test substance concentrations between 10 and 10,000 µg/plate.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- In the range-finding test, cytotoxicity was examined. No cytotoxicity was observed up to the highest test substance concentration of 10,000 µg/plate.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Table 7.6.1: Gene mutation assay (plate incorporation) results Average revertants per plate in tester strains TA98, TA 100, TA 1535, TA1537 and TA 1538 with and without S9-mix
Concentration [µg/plate]	S9	Revertants/plate [mean of 3 plates]
		TA 98	TA 100	TA 1535	TA 1537	TA 1538
DMSO	–	10	94	12	4	5
100	–	13	95	8	6	5
333	–	11	101	11	6	5
1000	–	11	99	10	6	5
3333	–	10	89	4	4	5
10000	–	11	102	11	5	5
Pos. control	–	211	673	412	123	351
DMSO	+	20	106	7	6	10
100	+	19	116	8	8	13
333	+	23	117	12	7	15
1000	+	16	112	11	6	14
3333	+	17	104	13	6	14
10000	+	17	117	10	6	12
Pos. control	+	285	500	46	36	400

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

In a reverse gene mutation assay according to Ames, isobutyl acetate was not mutagenic as it did not show any positive response (increasein the number of revertants of S. typhimurium) with any of the tester strains used either in the presence or absence of microsomal enzymes.

Executive summary:

In a reverse gene mutation assay in bacteria according to Ames (1975), strains of S. typhimurium (TA 98, TA 100, TA 1535, TA 1537, TA 1538) were exposed to isobutyl acetate at concentrations of 0, 100, 333, 1000, 3333, and 10000 µg/plate in the presence and absence of mammalian metabolic activation (S-9 mix from Aroclor 1254 induced rat liver) in a plate incorporation test.

 

Isobutyl acetate was tested up to the limit concentration of 10000 µg/plate. No toxicity or precipitation was observed. The positive controls induced the appropriate responses in the corresponding strains. Isobutyl acetate did not increase the number of revertants in any of the test strains. There was no evidence of induced mutant colonies over background. Isobutyl acetate was negative under test conditions.