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Toxicological information

Genetic toxicity: in vitro

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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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Full experimental details are not provided in the published paper
Justification for type of information:
The standard OECD 471 test is not suitable to test petroleum UVCBs, because it has a tendency to produce false negatives for these substances. Therefore, the petroleum industry has developed a Modified Ames assay, optimized to accurately identify positive results for this endpoint. This deviation from the prescribed testing procedure requires some further explanation which is given in the attached document. The document gives a brief history of the development of the Modified Ames test and outlines Concawe’s proposed work (as part of a wider testing strategy, see Annex 13) to further support the use of this test for PS.

Data source

Reference
Reference Type:
publication
Title:
Generation of bitumen fumes using two fume generation protocols and comparison to worker industrial hygiene exposures.
Author:
Kriech, A., Osborn, L., Wissel, H., Redman, A. Smith, L., Dobbs, T.
Year:
2007
Bibliographic source:
J Occup and Environ Hyg 4 (81) 6-19

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
other: ASTM Standard Method E 1687-04
Principles of method if other than guideline:
Modified Ames assay based on method described by Blackburn et al., 1986 and standardised as ASTM Standard Method E 1687-95 (ASTM, Philadelphia, PA, 1995). Enhanced method to detect PAH mediated mutagenic activity
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: low viscosity liquid hydrocarbon
Details on test material:
Four fume samples generated from tank headspaces containing paving bitumen
Distillation range, fluorescence and PAH content described in the attachment

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 98
Metabolic activation:
with and without
Metabolic activation system:
S-9 microsomal activation mixture
Test concentrations with justification for top dose:
Doses equivalent or similar to ASTM Standard Method E1687-04
Evaluation criteria:
Test criteria as follows:
MI greater than or equal to 1.0 = positive
MI less than 1.0 = negative

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Remarks:
MI 0.89 (TP-A sample)
Cytotoxicity / choice of top concentrations:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Remarks:
MI 0.98 (TP-B sample)
Cytotoxicity / choice of top concentrations:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
positive
Remarks:
MI 1.0 (TP-C sample)
Cytotoxicity / choice of top concentrations:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Remarks:
MI 0.69 (TP-D sample)
Cytotoxicity / choice of top concentrations:
not specified
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
Not mutagenic
Executive summary:

Samples of four paving fume condensates, collected form the headspace of heated storage tanks, were tested in a modifed Ames assay according to ASTM Standard Method E1687 -04. This method has been enhanced to detect PAH mediated mtagenic activity in petroleum substances.

Four samples were tested in S. typhimurium TA 98, with and without metabolic activation. Three samples were clearly negative (MI values < 1.0). The remaining sample was marginally positive with an MI value of 1.0.