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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
15 Jul 1982 - 15 Dec 1982
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1982
Report date:
1983

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 tested
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
(3aα,4β,7β,7aα)-octahydro-4,7-methano-1H-indene
EC Number:
220-585-8
EC Name:
(3aα,4β,7β,7aα)-octahydro-4,7-methano-1H-indene
Cas Number:
2825-82-3
Molecular formula:
C10H16
IUPAC Name:
(1R,2S,6R,7S)-tricyclo[5.2.1.0^{2,6}]decane
Test material form:
liquid
Specific details on test material used for the study:
- Name of test material as cited in the report : exo-tetrahydrodi(cyclopentadiene); JP-10
- Storage conditions: stored at room temperature in a safety cabinet.

Method

Target gene:
Histidine
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Details on mammalian cell type (if applicable):
Not applicable
Species / strain / cell type:
S. typhimurium TA 1538
Details on mammalian cell type (if applicable):
Not applicable
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254 induced rat liver microsomal fraction, S9
Test concentrations with justification for top dose:
1, 5, 10, 20 and 50 µl/plate
Vehicle / solvent:
DMSO
Controls
Negative solvent / vehicle controls:
yes
Remarks:
the highest volume of DMSO used
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
other: 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: preincubation

JP-10 which was immiscible with the top agar overlay was assayed using a preincubation modification of the Ames assay which alters the conditions of exposure of tester strains to test chemicals to enhance exposure. As for the standard assay, bacteria (0.05 ml), the metabolic activation mixture (0.5 ml) or saline (for assays in the absence of S9) and the test substance (0.05 ml or less) were combined in a test tube. Before the addition of 2.0 ml of top agar, however, the tubes containing bacteria, enzymes and test material were incubated at 37°C for 30 minutes with end-over-end rotation. At that time, the 2.0 ml of top agar was added and the top agar layer was plated in the usual way. The doses of positive control chemicals per plate were as follows: 2-aminoanthracene, 25 µg; 2-nitrofluorene, 5 µg; sodium azide, 1 µg; and 9-aminoacridine, 50 µg.
Rationale for test conditions:
A liquid pre-incubation modification (standard operating procedure #CB/M-818) was used to test JP-10 which was not compatible with the standard plate-incorporation assay since it formed oil-like droplets on the surface of the top agar layer.

Results and discussion

Test results
Key result
Species / strain:
S. typhimurium, other: TA98, TA100, TA1535, TA1537, TA1538
Metabolic activation:
with and without
Genotoxicity:
not determined
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
even at the lowest dose tested (1µl/plate)
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Even at the lowest dose tested (1 µl/plate) toxicity was severe enough to result in sparse background lawns. Many plates had no revertants rather than the number normally obtained as a result of spontaneous reversion.

Any other information on results incl. tables

Table of results: see attached document

Applicant's summary and conclusion

Conclusions:
Under the test conditions, the test material is too cytotoxic to determine its mutagenic potential.
Executive summary:

JP-10 was assayed by a preincubation modification of the Ames assay because it was immiscible with the agar medium used in this assay. Varying volumes of the undiluted test material were added directly to the bacteria and S9 (or saline) mixes for preincubation because JP-10 was not sufficiently soluble in DMSO to obtain the necessary concentrates for the desired doses. Even at the lowest dose tested (1 µl/plate) toxicity was severe enough to result in sparse background lawns. Many plates had no revertants rather than the number normally obtained as a result of spontaneous reversion.

The results of this assay are inconclusive due to severe toxicity of JP-10 on the tester strains. Although a repeat assay with shorter exposure times is recommended, we consider that further modifications of the standard protocol for this particularly toxic test substance are outside the scope of this present work assignment.