Hydrocarbons, C3-4

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP status unknown, tested according to standard NTP methodology. Minor restrictions in reporting but otherwise adequate for assessment. Not all OECD required tester strains used, but main ones covered.

Data source

Reference

Reference Type:

publication

Title:

Genetic Toxicology - Salmonella (297396)

Author:

National Toxicology Program

Year:

1993

Bibliographic source:

Internet link. http://ntp-apps.niehs.nih.gov/ntp_tox/index.cfm

Materials and methods

Test guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

NTP Standard Protocol

Deviations:

yes

Remarks:

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

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Reference substance 001

Cas Number:

74-82-8

Molecular formula:

C H4

Method

Target gene:

Histidine gene

Species / strain

Species / strain / cell type:

other: Salmonella strains TA1535, TA100, TA97 and TA98

Metabolic activation:

with and without

Metabolic activation system:

rat liver S9 and hamster liver S9

Test concentrations with justification for top dose:

0, 0.001, 0.002, 0.007, 0.013 and 0.027 µg/plate

Vehicle / solvent:

No data

Controls

Untreated negative controls:

yes

Positive controls:

yes

Positive control substance:

other: sodium azide, 9-aminoacridine, 2-nitrofluorene or 4-nitro-o-phenylenediamine, 2-aminoanthracene

Details on test system and experimental conditions:

The plate tests were conducted within a sealed dessicator (gas chamber) for exposure to gaseous substances.

Evaluation criteria:

A positive response was defined as a reproducible, dose-related increase in histidine-independent (revertant) colonies in any one strain/activation combination. An equivocal response was defined as an increase in revertants that is not dose related, is not reproducible, or is not of sufficient magnitude to support a determination of mutagenicity. A negative response was obtained when no increase in revertant colonies is observed following chemical treatment. There was no minimum percentage or fold increase required for a chemical to be judged positive or weakly positive.

Results and discussion

Test results

Species / strain:

S. typhimurium, other: Salmonella strains TA1535, TA100, TA97 and TA98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Cytotoxicity was observed (reduced numbers of colonies) at the higher dose levels in some tester strains in both the absence and presence of S9.

Remarks on result:

other: all strains/cell types tested

Applicant's summary and conclusion

Conclusions:

Interpretation of results:
negative with metabolic activation both rat and hamster S9
negative without metabolic activation

Methane was Ames negative in all of the strains tested both with and without metabolic activation

Executive summary:

Methane was Ames negative in all of the strains tested both with and without metabolic activation