Pitch, coal tar, high-temp.

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 Jul. - 03 Sep. 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

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 test

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Pitch, coal tar, high-temp.

EC Number:

266-028-2

EC Name:

Pitch, coal tar, high-temp.

Cas Number:

65996-93-2

Molecular formula:

not applicable

IUPAC Name:

Pitch, coal tar, high-temp.

Test material form:

solid

Details on test material:

pitch, coal tar, high-temp.; CCSG composite sample no. 8 (ATE 10444)
- Substance type: organic
- State of aggregation: bulk solid
- Density: ca. 1.32 g/cm³ (composite sample)
1.15 - 1.4 g/cm³ (typical range for coal-tar pitch)
- Composition of test material, percentage of components: 100 % (UVCB substance)

Specific details on test material used for the study:

- Name of test material (as cited in study report): pitch (coal tar)
- Lot/batch No.: ATE no. 10444
- 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

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

Species / strain 3

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and 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: 3.16, 10, 31.6, 100, 316, 1000, 2500, and 5000 µg/plate (TA 98, TA 100: +/-S9)
31.6, 100, 316, 1000, 2500, and 5000 µg/plate (TA 1535: +/-S9)
10, 31.6, 100, 316, 1000, 2500, and 5000 µg/plate (TA 1537, TA 102: +/-S9)
2nd experiment: 1.58, 5.0, 15.8, 50, 158, 500, 1580, and 5000 µg/plate (TA 98, TA 1537: +/- S9)
15.8, 50, 158, 500, 1580, and 5000 µg/plate (TA 100, TA 1535, TA 102: +/- 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

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

other: see Report p. 16

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. 22).

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium, other: TA 100, TA 1537

Metabolic activation:

with

Genotoxicity:

positive

Remarks:

reproducible, dose response

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:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

positive

Remarks:

reproducible, dose response

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium, other: TA 1535, TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

reproducible in both tests

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: yes, at test concentrations of >= 158 µg/plate

Any other information on results incl. tables

No biologically relevant increases in TA 1535 and TA 102.

Biologically relevant increases in TA 98 (-S9, reproducible) ==> Mutation factor =< 6.6

Biologically relevant increases in TA 98, TA 100, and TA 1537 (+S9) ==> Mutation factor =<24.6 in TA 98

Applicant's summary and conclusion

Conclusions:

The results of the bacterial reverse mutation test show a positive mutagenic response of pitch, coal tar, high-temp. in three out of five Salmonella typhimurium tester strains, in one with and without and in two only with metabolic activation.