Naphtha (petroleum), light steam-cracked, debenzenized, C8-16-cycloalkadiene conc.

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:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant, guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Details on test material:

- Name of test material (as cited in study report): Dicyclopentadiene/Codimer Concentrate
- Synonyms: DCPD/Codimer Concentrate, DCP97, H-25430
- CA Index name: Naphtha (petroleum), light steam-cracked, debenzenized, C8-16-cycloalkadiene concentrate
- Lot number: 121302
- Substance type: a distillate from a C8+ fraction of thermally processed pyrolysis gasoline obtained from ethylene production
- Physical state: colourless liquid
- Purity: Not applicable (The test substance was within specifications and the occurrence and distribution of isomers was as expected).
- Stability under test conditions: stable at room temperature below 70°F, protected from light and air
- Composition of test material, percentage of components:
29.175 wt % endo- and exo-DCPD
18.726 wt % C4-MCPD and C5-MCPD codimers
13.210 wt % MCPD dimer
12.903 wt % CPD-MCPD codimer
8.129 wt % C8 aliphatic and aromatic hydrocarbons
7.144 wt % C4-CPD and C5-CPD codimers
3.625 wt % MCPD-C7 dimer
2.771 wt % Tetrahydroindene
1.917 wt % Trimers
0.927 wt % C7 cyclic hydrocarbon
0.697 wt % C5 acyclic hydrocarbon dimer
0.634 wt % MCPD monomer
0.078 wt % CPD monomer
0.063 wt % C6 acyclic hydrocarbons

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:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

S9 from Aroclor induced rat liver

Test concentrations with justification for top dose:

15, 50, 150, 500, 1500 and 5000 µg per plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: ethanol

Controls

Negative solvent / vehicle controls:

yes

Remarks:

ethanol

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene, 2-nitrofluorene, sodium azide, 90aminoacridine, methyl methanesulfonate

Remarks:

+S9: All S.typh strains 1 µg/plate, E.coli 10 µg/plate. -S9: S. typh TA98 2-nitrofluorene 1 µg/plate, TA100 and TA1535 sodium azide 1 µg/plate, TA1537 9-aminoacridine 75 µg/plate, E.coli methyl methanesulfonate 1000 µg/plate

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48-72 hours

NUMBER OF REPLICATIONS: 3

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth

Evaluation criteria:

For each replicate plating, the mean and SD of the number of revertants/plate were counted. For a positive result, there must be a dose-related increase in the mean revertants/plate of at least one tester strain over a minimum of 2 increasing concentrations of test substance. Data sets for TA1535 and TA1537 were judged positive if the increase in mean revertants at the peak of the dose response ≥ 3 times the mean vehicle control value. Data sets for TA98, TA100 and WP2uvrA were positive if the increase in mean revertants at the peak of the dose response ≥ 2 times mean vehicle control value.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

some conditions beginning at 667, 1000 or at 5000 µg/plate

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

some conditions beginning at 667, 1000 or at 5000 µg/plate

Vehicle controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Interpretation of results:
negative with metabolic activation
negative without metabolic activation

Dicyclopentadiene/codimer concentrate did not cause a positive response in either the presence or absence of Aroclor-induced rat liver S9.

Executive summary:

Dicyclopentadiene/codimer concentrate was tested in a bacterial reverse mutation test using Salmonella typhimurium tester strains TA98, TA100, TA1535 and TA1537 and Escherichia coli tester strain WP2 uvrA in the presence and absence or Aroclor-induced rat liver S9.

In the mutagenicity test, no positive mutagenic response was observed. The dose levels tested were 15, 15, 150, 500, 1500 and 5000 ug/plate. Toxicity was seen with some concentrations starting at 1500 or at 5000 ug/plate. No precipitate was observed.

It is concluded that dicyclopentadiene/codimer concentrate (CAS 68478-10-4) did not cause a positive response in either the presence or absence of Aroclor-induced rat liver S9 and is considered not to be mutagen in this test system.