Melamine toxicity

In fires, melamine—phenolic laminates ignite slowly at high temperatures and bum slowly producing smoke that has about the same toxicity as wood smoke (17). 

Daylight fluorescent pigments (qv) are considered to be nontoxic. Since they are combinations of polymers and dyestuffs, the combined effect of the ingredients must be taken into account when considering the net toxic effect of these materials. Table 5 gives results of laboratory animal toxicity tests of standard modified melamine—formaldehyde-type pigments, the Day-Glo A Series, and the products recommended for plastic mol ding, Day-Glo Z-series. 

Both urea— and melamine—formaldehyde resins are of low toxicity. In the uncured state, the amino resin contains some free formaldehyde that could be objectionable. However, uncured resins have a very unpleasant taste that would discourage ingestion of more than trace amounts. The molded plastic, or the cured resin on textiles or paper may be considered nontoxic. Combustion or thermal decomposition of the cured resins can evolve toxic gases, such as formaldehyde, hydrogen cyanide, and oxides of nitrogen. 

Melamine ia a skin test on rabbits produced neither local irritation nor systemic toxicity. As a 10% solution ia methylceUulose, it caused no irritation ia the eyes of rabbits. Human subjects were given patch tests with melamine. No evidence of either primary irritation or sensitization was found. Such results suggest that melamine crystal may be handled ia ordinary iadustrial use without special hygienic precautions. 

Polyurethane foams do, however, suffer from one serious disadvantage. Unless modified they bum with copious evolution of smoke and toxic by-products, which has led to a number of fatal fires, particularly in domestic accommodation. To some extent the problem may be reduced by suitable upholstery covering, but as mentioned on p. 775 a number of countries have now made mandatory the use of fire retardent additives. At the time of writing there is considerable activity in the development of new safer systems, particularly in the use of amino materials such as melamine as additives. Further developments may also be expected in the near future. 

However, the decomposition of organic compounds does not always lead to nontoxic solutions. Mineralization of melamine (2,4,6-triamino-l,3,5-triazine) and other chemicals was accomplished on Ti02 Degussa P-25. The formation of cyanuric acid prevents the complete mineralization of melamine as observed for atrazine and other. v-tria/incs on Ti02 photocatalysts, and the toxicity of the photocatalyzed solutions was higher than initially found for melamine [199],... 

CPSC staff performed a preliminary assessment of the potential health risks associated with the use of selected FR chemicals in upholstered furniture foam. FR-treated foam samples that could be used to meet the draft standard and were available to the CPSC staff for testing included melamine tris(l,3-dichloro-2-propyl)phosphate (TDCP) a mixture containing triphenyl phosphate (TPP), phenol isopropylated phosphate (PIP), and octyl tetrabromobenzoate (OTB). Other flame-retardants that could be used in foam have been discussed by the U.S. EPA Design for the Environment Program. Based on limited exposure or toxicity data, the following preliminary conclusions were published in 2006 ... 

Melamine Cyromazine Toxic by ingestion. Causes skin and eye irritation upon contact. Same as above. 

Pet Food-Related Toxicity by Melamine and Cyanuric Acid... 

Shaffer, C. B. Melamine.- Acute and Chronic Toxicity, Am. Cyanamid, Central Medical Department Wayne, N.J., 1955. 

USE Convenient lab source of cyanic acid gas. In prepn of melamine, sponge rubber. Selective herbicide. Very toxic to certain types of barley and radishes. 

Therefore, melamine appears to exert its effect via precipitation and chronic mechanical irritation. Since chronic irritation is a known promoting function, this is a likely hypothesis of the mechanism of toxicity. This hypothesis is further supported by the absence of carcinogenicity in doses below the dose which results in bladder calculi. The conclusions reached from this mechanism indicate that a threshold exists at the dose resulting in calculi and safe limits on exposure for melamine should be based upon the acceptable daily intake even though the compound by some definitions is a carcinogen. 

Synonyms Methyiated-butyiated meiamine-formaidehyde resin Poly (melamine-co-formaldehyde), methylated/butylated Classification Formaldehyde copolymer Properties Dens. 1.096 flash pt. 110 C ref. index 1.5010 (20 C) Toxicology LD50 (oral, rat) > 5000 mg/kg, (skin, rabbit) > 5000 mg/kg toxic harmful by ing. inh., skin absorption irritating to eyes, skin, respiratory system sensitizer may cause allergic skin reaction cancer suspect agent mutagen... 

Properties Wh. gran, to pale yel. cryst. powd. sol. in water si. sol. in alcohol, acetone m.w. 180.17 dens. 1.25 dec. without melting 197-199 C Toxicology LD50 (oral, mouse) 350 mg/kg LDLo (subcut., rabbit) 500 mg/kg toxic by ing. mod. toxic by subcut. route TSCA listed Precaution Combustible Hazardous Decomp. Prods. Heated to decomp., emits toxic vapors of NOx Uses Comonomer for melamine-formaldehyde resins buffer, skin conditioner in cosmetics softener, antistat for hair care aikaii org. intermediate soaps component for fiame retardants... 

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