Hydrocarbons, steam-cracking tar middle

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:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non GLP, near guideline study, some restrictions in reporting but adequate for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1985

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

E. coli not included

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Naphtha, thermal cracked, residues, naphthalene cut

EC Number:

285-562-7

EC Name:

Naphtha, thermal cracked, residues, naphthalene cut

Cas Number:

85117-10-8

IUPAC Name:

85117-10-8

Constituent 2

Reference substance name:

rohnaphthalin-gemisch

IUPAC Name:

rohnaphthalin-gemisch

Details on test material:

- BASF test substance number: 83/142
- Storage +4°C
- No further details

Method

Species / strain

Species / strain / cell type:

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

Additional strain / cell type characteristics:

other: TA 98 and TA 100 have a modified post replication DNA repair system

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

0, 20, 100, 200, 300, 400, 500, 2500 and 5000 µg/plate

Vehicle / solvent:

- DMSO

Controls

Controls 1

Untreated negative controls:

yes

Remarks:

sterility control

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other:

Remarks:

all strains, with S9

Controls 2

Positive controls:

yes

Positive control substance:

other:

Remarks:

TA 100 and TA 1535, without S9

Controls 3

Positive controls:

yes

Positive control substance:

other:

Remarks:

TA 98, without S9

Controls 4

Positive controls:

yes

Positive control substance:

other: 100 μg 9-aminoacridine chloride monohydrate

Remarks:

TA 1537, without S9

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)
- Standard plate test: Test tubes containing 2 mL of soft agar (100 ml agar (0.6% agar + 0.6% NaCl) and 10 mL amino-acid solution: 0.5 mM histidine + 0.5 mM biotin) kept in a water bath at 45°C, and the remaining components are added in the following order: 0.1 mL test solution; 0.1 mL bacterial suspension; 0.5 mL S-9 mix (in tests with metabolic activation) or 0.5 mL phosphate buffer (in tests without metabolic activation).
- After mixing, the samples are poured onto the Vogel-Bonner agar plates (minimal glucose agar plates) within approx. 30 seconds.
- Preincubation test: 0.1 mL test solution, 0.1 mL bacterial suspension and 0.5 mL S-9 mix incubated at 37°C for the duration of 20 minutes. Subsequently, 2 mL of soft agar is added, and, after mixing, the samples are poured onto the Vogel-Bonner agar plates within approx. 30 seconds
- After incubation for 48 hours at 37°C in the dark, the bacterial colonies (his+ revertants) are counted.

NUMBER OF REPLICATIONS:
- For each test, 3 plates per dose or per control.

DETERMINATION OF CYTOTOXICITY
- Yes

CHECKING OF TESTER STRAINS
- The Salmonella strains are checked for the following characteristics at regular intervals: deep rough character (rfa); UV sensitivity (∆ uvrB); ampicillin resistance (R factor plasmid) .
- Histidine auxotrophy is automatically checked in each experiment via the spontaneous rate.

Evaluation criteria:

A substance is characterised as positive if it fulfils the following requirements: doubling of the spontaneous mutation rate (control); dose-response relationship; reproducibility of the results.

Statistics:

None specified.

Results and discussion

Test results

Test results 1

Species / strain:

other: S. typhimurium TA 1535 and TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

No increase in the number of his+ revertants

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

ambiguous

Remarks:

Only in 2 standard plate tests was a slight increase in the number of revertant colonies at 100 - 200µg by a factor 1.5-1.9 detected after metabolic activation.

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

other: In all 4 standard plate tests with S-9 mix a slight increase in the number of his+ revertants by a factor of 1.4-1.7 was observed at 100-200 µg/plate

Vehicle controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

Clear bacteriotoxic effect (reduced his^- background growth, decrease in the number of his⁺ revertants) at doses ≥200 µg/plate.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with and without metabolic activation

Rohnaphthalin-gemisch (CAS 85117-10-8) was negative with and without metabolic activation when tested in a bacterial reverse mutation assay.

Executive summary:

Rohnaphthalin-gemisch (CAS 85117-10-8) was tested in a bacterial reverse mutation test using Salmonella typhimurium tester strains TA98, TA100, TA1535 and TA1537 in the presence and absence or Aroclor-induced rat liver S9.

Toxicity was observed with some conditions at > 200 µg/plate. Small increases in revertant colonies seen in strains TA98 and 100, in only some of the experiments, were not seen on changing the test conditions (pre-incubation test to try to optimise any activity that may be present).  The increases in revertant colonies seen do not meet the criteria for a positive response and are considered not to indicate a mutagenic effect of the test material.

Rohnaphthalin-gemisch (CAS 85117-10-8) did not induce a significant increase in revertant colonies in Salmonella strains with or without rat liver metabolic activation at any dose level and is considered not to be a mutagen in this test system.