1,3,5-triazine-2,4,6-triamine phosphate

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 1

Reference Type:

publication

Title:

Chromosome Aberrations and Sister Chromatid Exchanges in Chinese Hamster Ovary Cells: Evaluations of 108 Chemicals

Author:

Galloway S.M. et al.

Year:

1987

Bibliographic source:

Environ. Mol. Mutagen., 10, 1-175

Reference 2

Reference Type:

secondary source

Title:

Prediction of chemical carcinogenicity in rodents from in vitro genotoxictiy assays

Author:

Tennant R.W. et al.

Year:

1987

Bibliographic source:

Science, 236, 933-941

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

yes

Remarks:

details on results (incl. cytotoxicity) and some details on the method are missing; differing positive control (with MA) was used

Principles of method if other than guideline:

according to NTP Standard protocol
(Galloway S. et al.: Environ. Mutagen., 7, 1)

GLP compliance:

not specified

Type of assay:

other: chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

Melamine

EC Number:

203-615-4

EC Name:

Melamine

Cas Number:

108-78-1

Molecular formula:

C3H6N6

IUPAC Name:

1,3,5-triazine-2,4,6-triamine

Method

Species / strain

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Metabolic activation system:

S9 mix from male SD rats induced with Aroclor 1254

Test concentrations with justification for top dose:

0; 240; 270; 300 µg/mL

Vehicle / solvent:

Vehicle(s)/solvent(s) used: DMSO (20 µg/mL)

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other: without MA: Mitomycin C (TEM, 0.5 µg/mL); with MA: cyclophosphamide (CP, 25 µg/mL)

Details on test system and experimental conditions:

DURATION
- Exposure duration:
with MA: 2hr - harvest time 10.5 hrs, without MA: exposure/harvest time 10.5 hours ; 2-3 hours before harvesting, colcemid was added

NUMBER OF CELLS EVALUATED: 100 cells were scored from each of the three highest dose groups having sufficient metaphases for analysis; 50 cells were scored from the positive controls

STAIN (for cytogenetic assays): Giemsa

NUMBER OF REPLICATIONS: presumably 3 (as stated in Galloway S. et al.: Environ. Mutagen., 7, 1)

DETERMINATION OF CYTOTOXICITY
(For most tests reported, doses were based on observations of cell confluence and mitotic cell availability in the SCE test)

Evaluation criteria:

All types of aberrations were recorded separately, but for data analysis they were grouped into categories of "simple" (breaks and terminal deletions), "complex" (exchanges and rearrangements), "other" (includes puverized chromosomes), and "total". Gaps and endoreduplications were recorded but were not icluded in the totals. Aberrations in polyploid cells were not scored but metaphases with 19-23 chromosomes were used.
For data analysis the "total" aberration category was used and the criterion for a positive response was that the adjusted P value was =<0.05

Results and discussion

Test results

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: No toxicity was observed, although some cell cycle delay was found in the SCE test.

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

Table 1.: Without Metabolic Activation

	Total aberrations; No of Abs/ % Cells	Complex aberrations No of Abs/ % Cells	Simple aberrations No of Abs/ % Cells	Other aberrations No of Abs/ % Cells
Vehicle/negative Control	3 3.0	1 1.0	0 0.0	2 0.02
Vehicle/Solvent Control	3 2.0	0 0.0	2 2.0	1 0.01
Positive Control	11 18.0	8 17.0	2 4.0	1 0.02
240 µg/mL	0 0.0	0 0.0	0 0.0	0 0.0
270 µg/mL	3 3.0	3 3.0	0 0.0	0 0.0
300 µg/mL	2 2.0	2 2.0	0 0.0	0 0.0

Table 2.: With Metabolic Activation

	Total aberrations; No of Abs/ % Cells	Complex aberrations No of Abs/ % Cells	Simple aberrations No of Abs/ % Cells	Other aberrations No of Abs/ % Cells
Vehicle/negative Control	1 1.0	0 0.0	0 0.0	1 0.01
Vehicle/Solvent Control	7 6.0	3 3.0	2 2.0	2 0.02
Positive Control	11 20.0	9 18.0	1 2.0	1 0.02
240 µg/mL	0 0.0	0 0.0	0 0.0	0 0.0
270 µg/mL	2 2.0	2 2.0	0 0.0	0 0.0
300 µg/mL	3 3.0	2 2.0	0 0.0	1 0.01