Melamine update

After my last melamine post, a visitor to the site wrote to me:

My wife and I had a baby two weeks ago. We’ve had some problems getting breastfeeding going. The hospital had us on one type of formula and then another (don’t remember the name of the first but the second was Nestle’s Good Start). So we’ve had him on a combination of breast milk and Good Start since we took him home on 11/20.

Then, I read yesterday on Daily Kos that trace amounts of melamine have been found in most domestic formula, and also that the FDA has issued some kind of flash advisory indicating that the detected levels of melamine are ‘safe’. So naturally, being the upstanding post-boomer parents that we are, we did a hard stop on the aforementioned formula and went to an organic powdered brand instead.

I’d still like a little more info about the underlying science of melamine. It’s an organic chemical. Check. What does that mean? It has 66 percent nitrogen. Check. Well, the air I breathe is 70 percent nitrogen. I guess I’m asking you to do my homework for me — but then, that’s your new job as a blogger, right? ;-) Net, why has this chemical wrought the death and illness that it has wrought? What more can you tell us about the underlying chemical processes?

Thanks for asking, Suneel, and congratulations on that new baby boy!

Melamine combines with cyanuric acid

From what I can determine, the problem is not melamine by itself. If an infant eats melamine, it gets absorbed through the digestive tract, goes into the blood stream, and is excreted in the urine. It doesn’t become part of the body, i.e., it’s not ‘metabolized.’ In three hours, half the melamine would be gone.

But melamine can interact with a substance called cyanuric acid. This is a white, odorless solid used to make bleach, disinfectants, and herbicides. If you add water to a cyanuric acid tablet and drop in a pair of dentures, you get bleached-white teeth. If an infant eats both melamine and cyanuric acid, the two can combine to form a crystal called melamine cyanurate.

I need to say a few simple words about chemical bonding. In the diagram on the left, the melamine atoms are in green and the cyanuric acid atoms are blue. Together they form melamine cyanurate. Notice that the melamine and the cyanuric acid are joined at hydrogen (H) atoms. These hydrogen bonds are quite strong.

In the larger diagram below, you can see that when you get a whole bunch of melamine and cyanuric acid together, they form a more complex crystalline struture. These crystals do not dissolve easily.
And that’s the problem.

When both melamine and cyanuric acid are present in our food supply, the crystals that they produce eventually make their presence known in the form of kidney stones. At least that’s what scientists currently think. It’s the crystals that produce the symptoms seen in infants in China: sand-like kidney stones in the urinary tract and, ultimately, kidney failure.

Where does this stuff come from?

So, where is the cyanuric acid coming from? It could be a contaminant of melamine: When melamine is broken down (by hydrolysis), cyanuric acid is a by-product. Melamine scrap, much cheaper than pure melamine, contains cyanuric adic. It could be introduced more directly: The FDA allows cyanuric acid as an ingredient in food additives for cattle. Cyanuric acid is also found in swimming pool water, some drinking water, and some fish.

So there are all kinds of ways this duo can come together.

The best official source of information I’ve found on this is a report by the World Health Organization (WHO), last updated on October 30, 2008. The contaminated ingredient (gluten) in the 2007 pet food contamination scandal contained 8.4% melamine and 5.3% cyanuric acid. The melamine was added deliberately because it mimics protein in a nutritional analysis. They state, diplomatically: “It is not known whether the cyanuric acid was also added deliberately or whether it was a by-product of the melamine preparation added.”
The FDA separately tests for both melamine and cyanuric acid, but they sometimes refer to cyanuric acid as a melamine-like compound or a melamine analogue. News reports sometimes state that melamine by itself causes kidney stones. I believe this is inaccurate; melamine has been associated with bladder stones in lab mice, but not kidney stones.
The role of cyanuric acid in melamine contamination is not widely reported, so melamine’s growing reputation as the evil-doer is a simplification, but perhaps an understandable one.

The current situation

Sadly, the number of infants in China affected by tainted milk products has risen from previous reports of 54,000 to 294,000. Deaths have risen from four to six. The US FDA continues to embarrass itself by its handling of the melamine mess, and they seem to know it. The Associated Press had to file a Freedom of Information Act request to get the FDA to release the names of contaminated milk products. Then the FDA said there were errors in the information it initially gave the AP.
I’m uncertain where the following sentence originated, but I’ve found over a dozen news stories with these exact same words: “The FDA said last month that the toxicity of cyanuric acid is under study, but that in the meantime it is ‘prudent’ to assume that its potency is equal to that of melamine.” The FDA employs real scientists. I’m just an educated science fan doing research on the web. If I’m wrong about the way melamine and cyanuric acid combine to create the problem we’ve seen in China, I’m sure someone will set me straight.

Name your poison

Just for fun, I’ve made a table that shows how many ounces of a toxic substance a 150-pound person needs to eat (or inhale) to have a 50 percent chance of dying. This table is usually presented in milligrams of substance per kilogram of body weight (usually the weight of rats, on which substances are tested). It’s called LD50: Lethal Dose 50% or Median Lethal Dose. For those of us who don’t enjoy the convenience of the metric system, I’ve added a conversion to ounces and pounds.

Melamine by itself, as a poison, is about as dangerous as table salt. But nothing happens in isolation, especially when it comes to something as intricate and complex as living organisms. I love science and I have great respect for medicine. But science, by definition, is limited to what can be observed and measured. On the other hand, health is determined by complex social and economic conditions that are subjective and difficult to quantify.
The environment, in the broadest sense of that word, is just as important to our health as the advances of scientific medicine. It’s certainly more important than any “healthy lifestyle” practice we may choose to adopt. We can avoid foods we know are contaminated – but only IF we know. And we have no way of knowing what’s coming next. What happened in China, and what threatens a widening swath of the world’s food supply, is a human tragedy that can’t be understood simply in terms of science.
And watch out for those poison dart frogs.

Related posts:
Melamine, cadmium, and Heidi Montag
To make more money
Eat fish? Don’t read this
Paging Dr. Frankenstein