Hydrocarbons, C4, 1,3-butadiene-free

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

Study dates not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Modified guideline study, GLP status unknown. Not all OECD required tester strains used , but main ones covered . Only illustrative data shown, sufficient for assessment of strains but not evaluation of any dose response or toxicity response.

Justification for type of information:

Justification for Category/Read-across approach:
See justification document for category approach and read-across to individual UVCB constituents in section 13.2.

Data source

Reference

Reference Type:

publication

Title:

In Vitro Microbiological Mutagenicity Studies Of Hydrocarbon Propellants

Author:

Kirwin CJ and Thomas WC.

Year:

1980

Bibliographic source:

J. Soc. Cosmet. Chem., 31, 367 - 370

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

Not all OECD required tester strains used , but main ones covered .

Principles of method if other than guideline:

A modified procedure was used to enable testing of a gaseous chemical.

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

n-Butane

IUPAC Name:

n-Butane

Constituent 2

Reference substance name:

Butane

EC Number:

203-448-7

EC Name:

Butane

Cas Number:

106-97-8

Molecular formula:

C4H10

IUPAC Name:

butane

Details on test material:

The hydrocarbon propellant tested was composed as follows: n-butane 99.7Mole% and isobutane 0.3Mole%

Method

Target gene:

Not specified

Species / strain

Species / strain / cell type:

other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100

Additional strain / cell type characteristics:

other: All histidine auxotrophs.

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9.

Test concentrations with justification for top dose:

5, 10, 20, 30, 40 and 50%

Vehicle / solvent:

None.

Controls

Untreated negative controls:

yes

Positive controls:

yes

Positive control substance:

other: methylene chloride

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)
- Duplicate agar plates, with Salmonella were prepared. The plates, without Iids, were placed on a perforated shelf inside a 9-liter desiccator, the latter was then sealed. The air was evacuated, then a known volume of test gas was introduced into the desiccator. Air was then introduced through a sterile cotton plug to normalise the pressure inside. The desiccator was then sealed and placed on a magnetic stir plate in a room which was maintained at 37°C. Magnetic stirrer bars, placed inside the base of each desiccator, facilitated mixing of the gases.

DURATION
- Exposure duration: The plates were exposed to the test gas for 6 hours, then incubated for an additional 40 - 45 hours before scoring.

NUMBER OF REPLICATIONS: 2

Evaluation criteria:

The spontaneous mutation frequency of each Salmonella strain remains relatively constant, however the mutation frequency may be greatly increased by a mutagen being added to the agar. The number of his+ revertants on each plate is counted and compared to the negative control.

Results and discussion

Test results

Species / strain:

other: S. typhimurium TA 1535, TA 1537, TA 1538, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Untreated negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

Results from the highest non-toxic concentrations are shown.

Table 1: Summary of results:

Metabolic activation	Conc of gas in the desiccators (v/v)%	Average histidine revertants per plate
		TA 1535	TA 1537	TA 1538	TA 98	TA 100
no	50	24	6	18	22	122
yes	50	26	4	37	48	134
no	Negative control	15	12	10	29	138
yes	Negative control	16	18	30	38	155
no	Positive control (2%)	34	10	16	234	900
yes	Positive control (2%)	52	12	52	237	1066

 

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with metabolic activation
negative without metabolic activation

Hydrocarbon propellant (containing 99.7% n-butane) was not toxic or mutagenic in any of the tested strains at concentrations up to 50%.

Executive summary:

In a modified Ames assay, hydrocarbon propellant (containing 99.7% n-butane) was not toxic or mutagenic in any of the tested strains at concentrations up to 50%. The positive control (methylene chloride) was mutagenic in strains TA98 and TA100 and was slightly mutagenic in TA1535.