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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
yes (incl. certificate)
Type of assay:
other: in vitro mammalian chromosome aberration test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Specific details on test material used for the study:
- Appearance: Slightly viscous; water-clear liquid
- Purity: 100%
- Specific gravity: 1.1254
- pH in a 50% solution: 7.51

Method

Species / strain
Species / strain / cell type:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Metabolic activation system:
rat liver S-9 mix
Test concentrations with justification for top dose:
35, 42, 50 mg/mL
Vehicle / solvent:
water
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
yes
Positive controls:
yes
Positive control substance:
triethylenemelamine
cyclophosphamide
Details on test system and experimental conditions:
- Dose selection: Appropriate concentrations for cytogenetic testing were determined by preliminary measurements of cytotoxicity to CHO cells using a broad range of concentrations from 1 - 50 mg/mL tested both the presence and absence of a rat liver S-9 metabolic activation system. Selection of a suitable range of concentrations for testing was based upon an estimate of the doses which would not excessively inhibit mitotic cell invasion of the treated cells. A maximum concentration of 50 mg/mL is tested for non-cytotoxic test chemicals.
- Test procedure: For evaluation of direct clastogenic potential, CHO cells were exposed to TEG and appropriate controls for a continuous 6- or 10-hour period without S-9 activation. Indirect genotoxic potential, requiring metabolic activation by liver S-9 homogenate, was studied with a 2-hour exposure period to test chemical and S-9 activation system. Following the 2-h exposure period, cells were rinsed, fresh medium was added and cells were then harvested at 6 and 10 h after the start of exposure. Chromosomes were prepared by standard procedures. A total of 50 cells/culture/harvest interval was examined for chromosome damage using duplicate cultures for the test agent and solvent controls. At least 5 dose levels were tested both with and without metabolic activation. Incidence of chromosome damage was determined for the highest 3 doses which did not produce excessive cytotoxic inhibition of cell division (mitosis).
Statistics:
Analyses of the test data employed the Fisher's Exact Test (one-tailed) to determine statistical significance and differences between the test and control populations.

Results and discussion

Test results
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Results obtained in this study demonstrated that the test substance did not produce significant increases in the proportion of cells with chromosome aberrations. The predominant type of chromosome damage observed in this study was simple chromatid breakage. None of the other types of typical chromosome damage scored in this test system were remarkable different from normal variations generally encountered with these cultured cells.

Applicant's summary and conclusion