Tar bases, coal, crude

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:

other information

Study period:

17 July - 17 Aug. 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Principles of method if other than guideline:

Plate incorporation assay

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

- Name of test material (as cited in study report): Coal tar base
- Molecular formula (if other than submission substance): not applicable
- Molecular weight (if other than submission substance): not applicable
- Substance type: organic
- Physical state: liquid
- Stability under test conditions: no measured data; based on chemical structure assumed to be stable
- Storage condition of test material: room temperature, exclusion of light

Method

Target gene:

Histidin operon

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 102

Metabolic activation:

with and without

Metabolic activation system:

Microsomal fraction prepared from induced livers of male Wistar rats, induced with phenobarbital (80 mg/kg bw) and ß-naphthoflavone (100 mg/kg bw) orally (3x)

Test concentrations with justification for top dose:

1st experiment: 0.0316, 0.100, 0.316, 1.0, 2.5, and 5.0 µL/plate (all strains, +/-S9)
2nd experiment: 0.25, 0.5, 1.0, 2.0, 3.5, and 5.0 µL/plate (all strains, +/-S9)

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: compatible with survival of bacteria and S9 activity

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

other: see: Any other information on materials and methods

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth/colony formation

Evaluation criteria:

Considered as mutagenic
- if a clear and dose-related increase in the number of revertants occurs in at least one tester with or without metabolic activation
and/or
- if a biologically relevant positive response for at least one of the dose groups occurs in at least one tester with or without metabolic activation.

An increase is considered relevant
- if in TA 100 and TA 102 mutation rate is at least twice as high as the rate of the solvent control;
- if in TA 98, TA 1535, and TA 1537 the mutation rate is at least 3x higher than that of the solvent control.

Statistics:

According to the OECD guidelines, the biological relevance is the criterion for the interpretation of the results: a statistical evaluation was not considered necessary under this premise (report p. 21).

Results and discussion

Test results

Test results 1

Species / strain:

other: S. typhimurium TA 100, TA 1535, TA 1537, TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

reproducible in both tests

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at >= 3.5 or 5 µL/pl. (+/-S9)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with

Genotoxicity:

positive

Remarks:

clear effect, reproducible in both tests

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 5 µL/pl.

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 98

Metabolic activation:

without

Genotoxicity:

negative

Remarks:

clear effect, reproducible in both tests

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at >= 3.5 µL/pl.

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: strain/cell type: S. typhimurium TA 100, TA 1535, TA 1537, TA 102

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Summary:

In the presence of S9 clear dose-related increases in the mutation rates were found in TA 98 in both experiments

[Doses 0.3 - 2.5 µL with mutation factors = 2.5 - 6.5x, and doses 0.5 - 3.5 µL with mutation factors = 2.0 - 3.9x above background, respectively]. The effect was produced by non-cytotoxic doses.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
positive with metabolic activation only in TA 98, other strains negative