Sep 29, 2008
Melamine Contaminated Milk
A brief summary and update to the Sciencebase original posts on Melamine in Milk and Melamine Scandal Widens.
Dairy farmers have been feeling the squeeze for years, particularly in parts of the world where technological advancement has been slow in coming and so their profit margins on their milk output have not been lifted by improved efficiency. In order to boost profits milk has been diluted. However, this brings with it the problem of falling quality – dilute with water and measurable concentrations of milk proteins, fats, and sugars fall. Dilution by up to 30% has not been uncommon, which is where melamine (as I’ve mentioned) comes in. Melamine is a small organic molecule with a high nitrogen content that can easily fool the quality control equipment into thinking that nitrogen (from protein) is present at normal levels and so the milk is passed as good.
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Laura – thanks for spotting that, it was a typing error. Melamine and cyanuric acid co-crystallise but obviously don’t produce uric acid crystals, I’ve fixed the text. However, the reference to coffee drinking and low water intake was not meant to be in reference to melamine, but to the risk of kidney stones for anyone drinking lots of caffeine and little water. I’ve clarified the text in that regard.
Your statements regarding melamine related kidney stones and kidney stone risks are slightly incorrect and potentially misleading.
Melamine and cyanuric acid do not form ‘uric acid’ stones. They form melamine-cyanurate stones, which are completely different from uric acid. For example, you seem to imply that consumption of melamine in milk together with coffee consumption and low water intake might put someone at a higher risk for these stones. That is not correct.
My guess is that this suggestion is guided by the fact that reduced water consumption and diuretic use (such as coffee) can exacerbate kidney issues related to uric acid. That is because uric acid is still quite water soluble and so, higher water consumption can largely prevent over-concentration of uric acid into uric acid stones. This is not the case with melamine-cyanurate. Melamine, and melamine-cyanurate are almost completely insoluble in water. They form these stones in kidneys in a large part because the pH in the kidneys is perfect for them to bind together, and only partially because of the concentration effect. So, while water consumption is important for overall health, it is not a risk factor people should be focusing on to reduce their risk for melamine-cyanurate kidney stones.
All the epidemological and food surveilance information to date (9/30/08) suggest that melamine related kidney stones are isolated to formula fed infants in China and Taiwan between late 2007 and August 2008. Additionally adults seem to be able to process much larger quantities of melamine contamination without these kidney problems. As a result I would encourage folks to focus on infant risks.
Finally while one doctor’s statement that melamine levels were ‘not that high’ may seem to bolster the idea that there is more than melamine in the infant health problems in china, I would highly doubt it for a number of reasons. 1. He was not looking at the full range of melamine concentrations in products. In economic adulturation cases such as these (especially when offenders are using such low grade starting material) actual concentrations can vary several order of magnitude, and a one time measurement does not capture what the concentrations have been over the lifetime of the infants in question. 2. His idea that melamine was ‘not that high’ may be irrelevant when the compound in question is really melamine AND cyanuric acid forming melamine-cyanurate salts in the kidneys. It is abundantly clear that melamine and cyanuric acid when co-ingested are harmful at concentrations an order of magnitude lower than either one alone. 3. The suggestion that ‘other chemicals could just as easily explain’ infant kidney problems in china misses the fact that there is a documented mechanism by which melamine and cyanuric acid contaminated food damages kidneys, causes kidney stone and failure in mammals. The concentrations of melamine in infant formula reported to date (100s of ppms) is more than sufficient to cause these exact effects. I have heard of no such evidence for any other compounds and I have heard of no problems with the melamine-cyanurate hypothesis fitting the symptoms of affected Chinese infants.
There are currently issues about milk products coming from china that has melamine in it. Around the world people are scared that their foods might also be contaminated with melamine. Philippines is one of those countries that have started to pull milk products from groceries that are suspected of high melamine content. Here’s 52 Milk Products that could be banned due to high Melamine Content in the Philippines.
I am actually surprised that melamine has turned out to be such a huge story. More than a year ago during the pet food scandal, there are news reports coming out of China that melamine was used in human food, such cake and other pastries to get better texture. Melamine had been assumed to be relatively safe for humans and pets were supposed to be the anomaly.
I posted a comment to your previous article wondering about the effects of long term exposure to melamine (an open question you note above as well). In the reply comments I was directed to an article with “translations” of the FDA S/RA, quite helpful to me as I’m not a toxicologist. From this I understood that related open questions include what happens upon heating melamine, and what happens in dehydrated kidneys.
For what it’s worth I thought I’d add that in China, baby formula (either prepackaged, or homemade using with milk powder and rice cereal) is boiled in order to kill contaminants in the water (all water must be boiled – in the finest hotels, the maids bring to you your thermos of boiled water each morning). It’s actually shocking how hot the babies learn to take their bottles. Who knows (apparently no one) what impact, if any, this has upon any melamine that might be present. Secondly, malnutrition and diarrhea in children are common problems in some areas of China; dehydration (and perhaps kidneys worse at clearing melamine) would be present as well. Finally, I do not know how common breastfeeding is in China, although it’s easy to find news stories this week on the “wet nurse revival” for Chinese parents of means.
One does wonder why the problem is not more widespread than we have heard. I would venture to guess that it is widespread, but even with the best of intentions it is very hard for the Chinese government to collect and disseminate data on its vast, and often rural, population. They don’t even really know how many people they have, let alone if or how many babies and children have fallen ill due to this specific problem.
Thanks for this helpful thread.