Background Paper on the Chemistry of Melamine Alone and in Combination with Related Compounds* Prepared for the WHO Expert Meeting on Toxicological and Health Aspects of Melamine and Cyanuric Acid In collaboration with FAO

* The views presented in this article do not necessarily reflect those of the United States Food and Drug Administration. 1 This chemistry background paper briefly summarizes key information on melamine related to past contamination incidents, uses, chemical structures and physicochemical properties (including the related triazines: cyanuric acid, ammeline and ammelide), manufacturing processes and product purity, complex formation and knowledge gaps. Since September 2008, when the current melamine contamination incident became widely known, the World Health Organization (WHO) reported that there have been three infant deaths, and " more than 47,000 infants and young children in China were hospitalized for urinary problems, possible renal tube blockages and possible kidney stones related to the consumption of melamine contaminated infant formula and related dairy products " (WHO, 2008). China's General Administration of Quality Supervision, Inspection and Quarantine conducted a national survey that revealed melamine contamination (from 0.1 to >2500 mg/kg) in powdered infant formulas produced by 22 Chinese companies (USFDA, 2008). Other countries have also reported detection of melamine in eggs (probably from contaminated feed) and milk-containing products manufactured in China, such as liquid milk, biscuits, candies, frozen yoghurt dessert and beverages. It appears that the contamination with melamine happened during milk production, where it had been intentionally added to raw milk at milk collection centres for at least 9 months (WHO, 2008). Several other melamine contamination incidents in pet food ingredients or products have been previously reported. Melamine has a high nitrogen content (66.6% by weight), which makes it attractive for economic adulteration as a fraudulent substitute for protein, especially when indirect protein assays based on total nitrogen are used. In 2007, melamine and related triazines were found at levels ranging from 0.8% to 26% in wheat gluten and rice protein extract imported from China that were used to manufacture pet food in the United States of America (USA) (Satzger, 2008). Pet food products contaminated by 0.001–0.7% melamine and related triazines (G. Diachenko, personal communication, 2008) led to the recall of 1154 pet food product types and are believed to have caused the deaths of more than 1000 dogs and cats due to kidney failure (Another incident of pet illnesses and acute renal failures occurred in several Asian countries during March 2004 due to pet food products manufactured at a single factory in Thailand (Brown et al., 2007). Recent chemical and histological analyses of tissues from the 2004 and 2007 incidents …