Registration Dossier

Toxicological information

Genetic toxicity: in vitro

Currently viewing:

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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Near-guideline, GLP-compliant study. Adequate for assessment.
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:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Principles of method if other than guideline:
Salmonella typhimurium TA98 exposed using either a standard plate incorporation assay or a modified protocol (8-fold increase in S9; 3-fold increase in NADP)
GLP compliance:
yes
Type of assay:
bacterial gene mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Viscous hydrocarbon liquid
Details on test material:
Catalytic cracked clarified oil (CCCO), CAS No. 64741-62-4.
Sample No API 81-15
Gravity degrees API: 0.1
Specific gravity: 1.0753
Viscosity in SUS 210 °F: 56.1
Flash Pt °F: 396
Ash, weight %: 0.05
Sulfur weight %:1.1
Pour Pt °F: 35
Asphaltenes (MM-596): 4.2 %
Carbon residue in weight %: 4.6

Method

Target gene:
hisD3052
Species / strain
Species / strain / cell type:
S. typhimurium TA 98
Details on mammalian cell type (if applicable):
not applicable
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with
Metabolic activation system:
Aroclor 1254-induced rat S9
Test concentrations with justification for top dose:
Trial 1: 1000, 5000, 10000, 25000, 50000 ug/plate
Trial 2: 33, 100, 333, 1000, 3333 ug/plate
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene (4 ug); perylene (50 ug)
Details on test system and experimental conditions:
Standard plate incorporation assay: 10% Aroclor 1254- induced rat S9 homogenate mix per ml; 4 mM NADP
Modified protocol: 80% S9 homogenate per ml; 12 mM NADP
Testing performed twice (independent repeat)
2-aminoanthracene and perylene used as positive control substances
Evaluation criteria:
Doubling in mutation frequency
Statistics:
None reported

Results and discussion

Test results
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
>10000 ug/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Remarks on result:
other: strain/cell type: Modified Ames assay using Salmonella typhimurium strain TA98
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

In both cases, significant and reproducible dose-dependent increases in the number of revertants were obtained.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive

positive in Salmonella typhimurium TA98 in vitro with and without metabolic activation
Executive summary:

The mutagenic potential of catalytic cracked clarified oil (up to 50000 µg/plate; sample API 81-15) was investigated in a non-guideline GLP-compliant study. Four separate tests were conducted in duplicate using S. typhimurium strain TA 98 in the presence of either 10% Aroclor 1254-induced rat liver S9 mix and 4 mM NADP or 80% S9 mix and 12 mM NADP; 2-aminoanthracene and perylene were used as positive control substances. A two-fold increase in revertants per plate was regarded as a positive response.

The test substance was positive in all 4 tests, with the number of revertants increased maximally 13.1, 27.8, 44 and 46.3-fold, respectively over solvent controls. The largest increase in revertants occurred in the assays activated with 80% S-9 and 12 mM NADP. A satisfactory response was obtained with the positive control substances.