Let me start by saying that this is not an article about whether melamine dinnerware is safe. We personally don't use melamine dishes, because we're waiting for more scientific evidence that toxic chemicals (like formaldehyde) don't migrate from them into our food.
Rather, this is an exploration of the difference between the organic compound melamine, and melamine in combination with other materials. I'm hearing a lot of confusion about the melamine found in China's milk, and since I've already been researching the topic, I thought this would be a great way to begin a series on melamine in general.
What is Melamine?
According to the FDA, Wikipedia and Wise Geek, melamine is an organic-based chemical substance. It can be combined with formaldehyde to create a hard plastic (or resin) used in utensils, plates, laminates (such as Formica countertops), and in fire retardant fabric. A special form of melamine resin is melamine foam, which is used mainly as an insulating and soundproofing material and more recently as a cleaning abrasive.
Wikipedia also points out that melamine resin utensils and bowls are not microwave safe, as they absorb the microwave radiation and heat up. The dishes are also not recyclable.
What Type of Melamine Was Found in Milk?
I found an amazing discussion about this on the Prudence, M.D. blog. Tess explains that it was most likely melamine combined with cyanuric acid added to the milk:
The high nitrogen level (66% of nitrogen mass) in melamine gives it analytical characteristics of protein molecules and thus, when milk gets checked for protein levels, it registers a higher level than the actual. However, it’s not solely melamine that is causing the renal failure in those who have consumed the contaminated dairy products. Most often cyanuric acid appears as an impurity of melamine.
[Cyanuric acid] can exist in low levels in human food (because of animals fed with feeds containing melamine and its structural analogs) but not necessarily due to adulteration. If taken at higher levels with melamine, due to chronic and continuous use, the combination of melamine and cyanuric acid could produce melamine cyanurate, forming spore-like crystals in aqueous solutions and can block the renal tubules, causing renal damage and failure, since melamine is not metabolized and is eliminated through the urinary tract.
This was the issue with the pet food scandal in 2007. The Scientific American gives a comparative description of both scenarios:
What does melamine do in the body? A Cornell veterinarian told us last year that melamine is not considered to be “a very toxic compound,” but can result in kidney stones and kidney failure especially in small animals. Investigators found crystals made up of melamine and its byproducts in the urine and kidneys of in the dogs and cats that were poisoned last year. Because it formed crystals in the body and was not fully dissolved in urine, the melamine gathered in the kidney, gunking up the organ and forming stones. The pets that died suffered acute kidney failure. Now the same thing appears to be happening to China's tiny tots.
Very interesting. At least now we can see the fundamental difference between the singular form of melamine and melamine resin. I'll keep you updated as new research on melamine resin becomes available.
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