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Diss Factsheets

Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
genetic toxicity in vitro, other
Remarks:
Allium chromosome aberration test
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1982
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment

Data source

Reference
Reference Type:
publication
Title:
Chromosome aberration assays in Allium: A report of the US Environmental Protection Agency Gene-Tox Program
Author:
Grant WF
Year:
1982
Bibliographic source:
Mutation Research 99 (1982) 273-291
Report date:
1982

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Breaks, exchanges and gaps involving subchromatid, chromatid, and chromosomate aberrations and rearrangements can be seen in Allium cepa, whose morphological characteristics are established and can be compared to determine the effect of a potentially mutagenic chemical.
GLP compliance:
not specified
Type of assay:
other: Allium chromosome aberration assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Purin-6(1H)-one
EC Number:
200-697-3
EC Name:
Purin-6(1H)-one
Cas Number:
68-94-0
Molecular formula:
C5H4N4O
IUPAC Name:
hypoxanthine
Test material form:
solid: particulate/powder

Method

Species / strain
Species / strain / cell type:
other: Allium cepa
Test concentrations with justification for top dose:
no test concentration specified
Vehicle / solvent:
Vehicle not specified
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
ethylmethanesulphonate
Details on test system and experimental conditions:
GENERAL PROCEDURE
Young onion bulbs of 10-30 g are prepared so that the apices of the root primordia are exposed. The bulbs are cultured in tap water (submerged 1/4 the depth of the bulb) aerated by continuous bubbling in the dark 2-5 days at 20°C. The mitotic cycle and period of DNA is measured.
When the root tips are 1-5 cm in length, the bulbs are transferred to a similar vessel containing the test substance in solution. Treatment times vary between 2 to 24 hours.
Chromosome aberrations aberrations are scored at different stages in the cell cycle, so recovery period prior to fixation includes one complete cell cycle.
After the recovery period, the root tips are fixed immediately or pretreated with colchicine or 8-hydroxyquinoline prior to fixation for accumulation of metaphases. Then, they are fixed in 95% alcohol-alcial acetic acid from 30 min to 24 hours, stored in 70% ethanol, and then stained at any point using aceto-carmine, aceto-orcein, or Feulgen reagent procedures.
To prepare slides, samples are treated with 5% pectinase for 1-3 hours. On each slide, the meristematic region is pressed in a drop of 45% acetic acid and mounted with a coverslip and a temporary seal.
Evaluation criteria:
The number of specifci type of aberration per 100 cells or the total number of aberrations per 100 cells.

Results and discussion

Test results
Key result
Species / strain:
other: Allium cepa
Metabolic activation:
not specified
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified

Applicant's summary and conclusion

Conclusions:
The test substance, Hypoxanthine, tested negative in the Allium chromosomal aberration test.
Executive summary:

The test substance, Hypoxanthine, tested negative in the Allium chromosomal aberration test.