Melamine is a monomer (chemical name 1,3,5-triazine-2,4,6-triamine ) used in combination with formaldehyde to produce amine resins. It has various applications in plastic materials (such as the famous Formica), adhesives, fire retardants etc.
If swallowed it can interfere with or block renal functions or lead to stone formation.
In September 2008, melamine was discovered in powdered milk in China and in dairy products where it poisoned thousands of babies. Melamine is rich in nitrogen (in proteins) and can invalidate tests and increase apparent protein concentrations.