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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:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
publication
Title:
Primary mutagenicity screening of food additives currently used in Japan
Author:
M. Ishidate, JR et al.
Year:
1984
Bibliographic source:
Fd Chem. Toxic. Vol, 22, No. 8, pp. 623-636, 1984

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
no
Type of assay:
other: in vitro mammalian chromosome aberration test

Test material

Constituent 1
Chemical structure
Reference substance name:
Disodium hydrogenorthophosphate
EC Number:
231-448-7
EC Name:
Disodium hydrogenorthophosphate
Cas Number:
7558-79-4
Molecular formula:
H3O4P.2Na
IUPAC Name:
disodium hydrogen phosphate

Method

Species / strain
Species / strain / cell type:
mammalian cell line, other: Chinese hamster lung fibroblast cell line (CHL)
Details on mammalian cell type (if applicable):
- Type and identity of media: Minimum Essential Medium (MEM;GIBCO) supplemented with 10 % calf serum
- Properly maintained: yes
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
without
Test concentrations with justification for top dose:
Three concentrations up to a maximum of 1 mg/mL (the highest non cytotoxic dose used in this experiment)
Vehicle / solvent:
- Vehicle used: physiol. saline
- Justification for choice of vehicle: Solubility of the test substance was adequat in this vehicle.
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
no
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 24 and 48 hours

SPINDLE INHIBITOR (cytogenetic assays): Colcemid (0.2 µg/mL) was added to the cultures two hours befor harvesting.
STAIN (for cytogenetic assays): with Giemsa solution (1.5 %; at pH 6.8)

NUMBER OF REPLICATIONS: 1

NUMBER OF CELLS EVALUATED: 100 well spread metaphases were analysed.

OTHER EXAMINATIONS:
- Determination of polyploidy: Yes
Evaluation criteria:
The results were considered to be negative if the incidence was less than 4.9 %, equivocal if it was between 5.0 and 9.9 %, and positive if it was more than 10.0 %.

Results and discussion

Test results
Key result
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not determined
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
not examined

Applicant's summary and conclusion

Conclusions:
Under the described test conditions, sodium phosphate monobasic is regarded as not clastogenic.
Executive summary:

In a chromosome aberration test equivalent or similar to OECD guideline 473, a Chinese hamster fibroblast cell was exposed to sodium phosphate monobasic (three different doses for 24 h and 48 h). The maximum dose of each sample was choosen via a preliminary test (dose needed for 50 % cell-growth inhibition). Untreated cells and solvent-treated cells were used as negative controls when the incidence of aberrations was less than 3 %. The results were considered as negative if the incidence was <= 4.9 % and positive if it was > 10 %. The test results for sodium phosphate monobasic were negative.

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