Registration Dossier

Administrative data

Key value for chemical safety assessment

Additional information

Melaminephosphate was tested in the Salmonella typhimurium reverse mutation assay with four histidine-requiring strains of Salmonella typhimurium (TA1535, TA1537, TA100 and TA98) and in the Escherichia coli reverse mutation assay with a tryptophan-requiring strain of Escherichia coli WPrUvrA (Verspeek-Rip, 2002) . The test was performed in two independent experiments in the presence and absence of S9-mix (Aroclor-1254 induced rat liver S9-mix). The substance was tested up to concentrations of 5 mg/plate in the absence and presence of S9-mix. It precipitated on the plates at this dose-level. The bacterial background lawn was not reduced at all concentrations tested and no biologically relevant decrease in the number of revertants was observed.

The chromosome aberration study with melamine was performed according to the US NTP standard protocol which is similar to the procedure outlined in OECD testing guideline 473. Chinese hamstoer Ovary (CHO) cells were used together with and without S9 mix prepared from the liver of arochlor 1254 induced rats. Applied doses were 240, 270 and 300 µg per plate. Mitomycin C and cyclophosphamide were used as positive controls. Melamine was found to be non clastogenic in vitro. Considering the higher molecular weight of melamine phosphate and that both are of comparable solubility in water, this data is adequate to conclude that melamine phosphate is not clastogenic in vitro.

Mutagenicity in mammalian cells in vitro was assessed in the mouse lymphoma assay performed according the US National Toxicology Standard Program which is comparable to OECD testing guideline 476 (McGregor 1988). Concentrations of

melamine were 0; 10; 20; 40; 80; 100; 120; 140; 160 µg/ml ; testing of melamine was limited to 160 µg/ml by its solubility in the exposure medium. A dose-dependent increase in mutant frequency was observed for the postive control , but not for the solvent control DMSO and not for melamine. The cloning efficiency was not affected by melamine.

Considering the higher molecular weight of melamine phosphate and that both are of comparable solubility in water, this data is adequate to conclude that melamine phosphate is not mutagenic to mammalian cells in vitro.

Melamine was investigated in a micronucleus study in vivo (Shelby 1993). Groups of five mice were administered the substance at 0, 500, 1000 or 2000 mg/kg

by intraperitoneal injection on three consecutive days. Two days after the third treatment, animals were sacrificed and bone marrow and peripheral blood smears prepared. Per animal, two slides per tissue were prepared. The initial test gave a positive trend (P = 0 .003) from 2 .1 in the control to 3 .8 in the high dose (2,000 mg/kg) . Peripheral blood smears from the dose determination test were scored and were negative as was a repeat bone marrow test using doses of 1,000 and 2,000 mg/kg.

Short description of key information:
Melaminephosphate was found to be non mutagenic in a GLP-und OECD guideline 407-compliant Ames test (Verspeek-Rip, 2002). Adequate experimental data on chromosome aberration, mutagenicity in mammalian cells in vitro and genotoxicity in vivo showing absence of genotoxic properties has been published for melamine (Galloway 1987, McGregor 1988, Shelby 1993).

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

The available studies are considered reliable and suitable for classification purposes under 67/548/EEC. As a result the substance is not considered to be classified for genotoxicity under Directive 67/548/EEC, as amended for the 28th time in Directive 2001/59/EC.

Classification, Labelling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is not considered to be classified for genotoxicity under Regulation (EC) No. 1272/2008.