Propene

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, guideline study, fully adequate for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

minor modifications to the method as the test item is a gas at ambient temperature

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Propene

EC Number:

204-062-1

EC Name:

Propene

Cas Number:

115-07-1

Molecular formula:

C3H6

IUPAC Name:

prop-1-ene

Constituent 2

Reference substance name:

Propylene

IUPAC Name:

Propylene

Details on test material:

- Batch No. U05278
- >99% purity
- gas at ambient temperature
- expiry date assigned by Inveresk: 01.10.03

Method

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Additional strain / cell type characteristics:

not applicable

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A pKM 101

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

S9 prepared from liver of Aroclor 1254 induced male Fischer 344 rats.

Test concentrations with justification for top dose:

0, 0.031, 0.063, 0.125, 0.25 and 1%.

Vehicle / solvent:

Air

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Air

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene (2-AAN), Ethylene oxide (ETHOX), 9-aminoacridine (9-AA), 2-nitrofluorene (2-NF) and N-ethyl-N-nitro-N-nitrosoguanidine (ENNG)

Remarks:

The positive control substances, except ethylene oxide, were dissolved in DMSO. Ethylene oxide was tested as a mixture in air.

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation) Vogel-Bonner Medium E agar with 2% glucose

DURATION
- Preincubation period: 3 days
- Exposure duration: 48 h
- Expression time (cells in growth medium): 24 h

NUMBER OF REPLICATIONS: 2

Evaluation criteria:

Positive mutagenic response if there was:
i) at least a 3-fold increase over the mean concurrent vehicle control values at some concentration of the test item (S. typhimurium strains TA 1535, TA 1537, TA 98, E. coli); or a 2-fold increase (S. typhimurium strain TA 100). If the mean colony count on the vehicle control plates was less than 10, then a value of 10 was assumed for assessment purposes. In such cases, a minimum count of 20 was required before a positive mutagenic response was registered.
And,
ii) a dose related response, although at high dose levels this relationship could be inverted because of, for example, (1) toxicity to the bacteria generally, (2) specific toxicity to the mutants and (3) inhibition of foreign compound metabolising enzymes where mutagens require metabolic activation by the liver

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

other: an increase was seen only in one strain, reaching 3-fold over background in one experiment and hence was considered of little biological relevance

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

E. coli WP2 uvr A pKM 101

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

The weak positive response in the presence of S9 may be due to the generation of trace levels of propene oxide.

Remarks on result:

other: strain/cell type: weakly mutagenic in TA1535 only

Applicant's summary and conclusion

Conclusions:

Interpretation of results:
negative with metabolic activation with the exception of a weakly mutagenic response in TA1535 only
negative without metabolic activation

Propene was weakly mutagenic in strain TA1535 in the presence of S9 mix, when tested in air at a concentration of 1%. No mutagenic activity was observed with any of the other Salmonella strains tested or with Escherichia coli.

Executive summary:

In the main study, propene was tested for mutagenic activity according to the OECD 471 guideline protocol in Salmonella typhimurium strains TA1535, TA1537, TA98 and TA100 and Escherichia coli WP2uvrA (pKM101) at exposure levels ranging from 0.031% to 1.0% in air. The highest concentration was selected to be one half of the lower explosivity limit for propene, which is 2.2%

Two mutation assays were conducted on agar plates in the presence and absence of an Aroclor-1254 induced rat liver preparation and the co-factors required for mixed-function oxidase activity (S9 mix). Concurrent positive controls demonstrated the sensitivity of the assay and the metabolising activity of the S9 mix. The results obtained in the first and second mutation assays were similar. A weak, mutagenic response was observed with TA1535, in the presence of S9 mix only, and only at the highest concentration of propene (1%). In both assays, a 2-fold increase over the vehicle control group was observed at 0.5%. In the first mutation assay the mean colony number at the highest concentration of 1% met the required criterion for a positive result, namely a 3-fold increase over the concurrent vehicle control value. In the second mutation assay, the mean colony number of 38 was just below the 3-fold value of 39.

The weak positive response in the presence of S9 may be due to the generation of trace levels of propene oxide. No toxicity to the bacteria was observed in either mutation assay, in either the presence or the absence of S9 mix.

(Note: A sighting study, Inveresk 2003b, was carried out with exposure levels ranging from 3.125% to 100% propene. In this assay, TA1535 demonstrated a 3 -fold increase in the incidence of mutant colonies over the vehicle control group at all exposure levels below 100% in the presence of S9 mix. With the other four Salmonella strains tested, as well as Escherichia coli, propene was not mutagenic.)