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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
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The reliability and summary were made based on the HPV program adopted during OECD SIAM 25 (October 2007). Only limited information is available on methods and results; the article is a review article of more than 200 investigated substances.

Data source

Reference
Reference Type:
publication
Title:
Primary mutagenicity screening of food additives currently used in Japan
Author:
Ishidate Jr M, Sofuni T, Yoshikawa K, Hasashi M, Nohmi T, Sawada M and Matsuoka A
Year:
1984
Bibliographic source:
Fd Chem Toxic 22: 623-636

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
no metabolic activation used, cytotoxicity not measured, exposure durations of 24 and 48 hours, 100 metaphases investigated
GLP compliance:
no
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: Sodium nitrate
- Analytical purity: 99.3 %

Method

Species / strain
Species / strain:
other: Chinese hamster fibroblast cell line, CHL
Details on mammalian cell lines (if applicable):
- Type and identity of media: minimum essential medium (MEM), supplemented by 10 % calf serum
- Other: The cell line was originally established from the lung of a newborn female at the Cancer Research Institute, Tokyo (Koyama, Utakoji and Ono, 1970). The modal chromosome number was 25 and the doubling time was approximately 15 hours.

Reference
- Koyama H, Utakoji T and Ono T (1970). A new cell line derived from newborn Chinese hamster lung tissue. Gann 61: 161-167.
Metabolic activation:
without
Test concentrations with justification for top dose:
5 mg/mL (highest dose tested), maximum dose selected in a preliminary test (not reported), 3 different concentrations (not given)
Vehicle:
- Vehicle/solvent used: physiological saline
Controls
Negative controls:
yes
Solvent controls:
yes
True negative controls:
not specified
Positive controls:
not specified
Positive control substance:
not specified
Details on test system and conditions:
DURATION
- Exposure duration: 24 and 48 hours

SPINDLE INHIBITOR
- Colcemid (added 2 hours prior to cell harvesting)

FIXATION
- Cells were fixed with acetic acid-methanol (1:3 v/v)

STAIN
- Giemsa

NUMBER OF CELLS EVALUATED
- 100 well-spread metaphases were observed
Evaluation criteria:
The result was considered to be negative if the incidence of aberrations was less than 4.9 %, equivocal if it was between 5.0 and 9.9 % and positive if it was more than 10 %.
Statistics:
For a quantitative evaluation of the clastogenic potential, the D20 was calculated, which is the dose (mg/mL) at which structural aberrations (including gaps) were detected in 20 % of the metaphases observed.
In addition, the TR value was calculated, which indicates the frequency of cells with exchange-type aberrations per unit dose (mg/mL).

Results and discussion

Test results
Species / strain:
other: Chinese hamster fibroblast cell line, CHL
Metabolic activation:
without
Genotoxicity:
positive
Remarks:
24 % structural aberration at 48 hours
Cytotoxicity:
not specified
Vehicle controls valid:
other: incidence of aberrations usually less than 3.0 %
Negative controls valid:
other: incidence of aberrations usually less than 3.0 %
Positive controls valid:
not specified
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.
Additional information on results:
D20: 5.73 mg/mL
TR: 0.8
Also positive at 4 mg/mL at both 24 hours (10.0 %) and 48 hours (10.0 %).

Applicant's summary and conclusion