Trilithium orthophosphate

Genetic toxicity: in vitro

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

Test material information

Constituent 1

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.