Pitch, petroleum, arom.

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Pitch, petroleum, arom. showed a positive response in a bacterial reverse mutation assay (Ames test). Furthermore, the substance is classified as mutagenic Cat. 1B due to its benzo[a]pyrene content of up to 0.14 %.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 Aug. - 01 Sep. 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

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

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: 31.6, 100, 316, 1000, 2500, and 5000 µg/plate (+/-S9)
2nd experiment: 62.5, 125, 250, 500, 1000, 3000, and 5000 µg/plate (TA 98, TA 100, +/- S9)
125, 250, 500, 1000, 3000, and 5000 µg/plate (TA 1535, TA 102, +/- S9)
15.8, 50, 158, 500, 1580, and 5000 µg/plate (TA 1537, +/- S9)

Vehicle / solvent:

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

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

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. 21).

Species / strain:

S. typhimurium, other: TA 98, TA 100, TA 1537

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

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 >= 31.6 µg/plate

Considerable mutagenic activity was found in the absence of metabolic activation: a maximum mutation factor of 33.4 was reached in TA 98 at a dose of 3000 µg/plate.

Conclusions:

Interpretation of results (migrated information):
positive

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Additional information

Additional information from genetic toxicity in vitro:

Mutagenicity of pitch, petroleum, arom. (petro pitch) was tested in a bacterial reverse mutation assay (Ames test) according to OECD TG 471/EU Method B.13/14. Petro pitch proved to be positive in three of five tester strains. Additional cytotoxicity/mutagenicity tests were not conducted as pitch petroleum, arom, is self-classified as mutagenic (Muta. 1B) and carcinogenic (Carc 1B) due to its content of benzo[a]pyrene (≥ 0.1 %), a substance classified as carcinogenic and mutagenic (Carc. 1B, Muta.1B).

Justification for classification or non-classification

Pitch, petroleum, arom. (petro pitch) contains benzo[a]pyrene (BaP) in concentrations up to 0.14 %. BaP is known to be mutagenic and is classified as mutagenic Cat. 1B. In an Ames test, petro pitch was demonstrated to be mutagenic. Based on BaP content, pitch, petroleum, arom. is classified as mutagenic Cat 1B by the registrant.