Melamine Contamination Expands

The latest in the investigation of melamine in Chinese milk and milk-containing products is the revelation that Cadbury chocolates may contain the contaminant. According to the AP, the British candy maker is recalling 11 of its products made at a Beijing plant, which were distributed in Taiwan, Hong Kong, and Australia.

The Xinhua News Agency reports that 22 people in Hebei Province—including managers of pastures, breeding farms, and milk-purchasing stations—have been detained under the suspicion of making or selling melamine and putting the contaminant into milk. Police seized nearly 500 pounds of the toxin in connected raids.

Last year, melamine (along with cyanuric acid) caused renal dysfunction or failure in unknown numbers of domestic cats and dogs as a result of pet food made with contaminated Chinese wheat gluten. In the September 1 issue of the Journal of the American Veterinary Medical Association, investigators reported their findings in 70 cats from a single, commercial cattery* that were inadvertently fed tainted pet food.

Forty-three cats developed clinical signs of disease, including lethargy, poor eating, vomiting, polydipsia, and polyuria. More than half of the cats (38 of 68) that were biochemically analyzed developed azotemia, and 1 cat died. Among the 13 cats that were euthanized, kidney specimens revealed crystal-associated tubular necrosis and perivascular inflammation.

Cyanuric acid, which is produced by the hydrolysis of melamine, forms insoluble (or poorly soluble) crystals when combined with melamine. According to the FDA, cyanuric acid may be generated in the production of melamine or by its degradation. 

There are no news reports, as yet, regarding the content of cyanuric acid in the currently tainted Chinese milk products.

* Cats were used to assess the "routine palatability and acceptability" of commercial cat foods.

Photomicrograph of cat renal tubule containing gold-brown circular crystals of melamine and cyanuric acid (arrow); bar = 50 microns. Source: Ciancolo RE et al. J Am Vet Med Assoc. 2008;233:729-737.