Melamine
Melamine is used to manufacture melamine-formaldehyde resin, a type of plastic known for its flame retardant properties and commonly employed in countertops, dry erase boards, etc. Melamine itself is nitrogen-rich and is sometimes illegally added to food products to increase their apparent protein content. It has also been employed as a nonprotein nitrogen, appearing in soy meal, corn gluten meal and cottonseed meal used in cattle feed. Melamine is known to cause renal and urinary problems in humans and animals when it reacts with cyanuric acid inside the body, sometimes present in drinking water and in animal feed, so its use in food production is universally banned.
The Kjeldahl and Dumas methods used to test for protein levels fail to distinguish between nitrogen in melamine and naturally occurring in amino acids, allowing the protein levels to be falsified. Introduced into milk, it can help conceal its fraudulent dilution with water. Melamine adulteration of food products also made headlines when pet food was recalled in Europe and the U.S. in 2007.
Read more about this topic: 2008 Chinese Milk Scandal