Melamine is a cyclic molecule made from urea which contains 66% nitrogen by weight. Melamine in combination with formaldehyde is used to produce melamine resin, a very durable thermosetting plastic. Formica counter tops and Melmac dinner plates are made from melamine resins.
Recently, several Chinese food products have been found to be intentionally contaminated with melamine. In 2007 several brands of pet food were recalled after thousands of dogs died of kidney failure. This month, China recalled more than 700 tons of infant formula containing melamine following the death of several children and over 50,000 cases of illnesses. Tests found that melamine had been added illegally to baby formula in order to increase the apparent protein content. Standard tests such as the Kjeldahl and Dumas tests estimate protein levels by measuring the nitrogen content. Adulterating watered down milk with nitrogen-rich melamine fools these tests.
Melamine-contaminated products from China have made their way around the globe. The latest impact is the recall of instant coffee and milk chocolate products from Kraft Foods, Mars, and Cadbury. Melamine is nontoxic in low doses, but it can combine with other chemicals to form insoluble compounds that cannot be excreted.
The Food and Drug Administration (FDA) set 2.5 parts per million as the maximum “tolerable” amount of melamine that could be safely consumed in foods, but the agency was not able to determine a safe amount for baby formula. Melamine levels in imported Chinese candies recalled in California were as high as 520 parts per million.