Category: Biology

Thousands of babies had apparently taken ill having drunk formula milk to which the organic compound melamine had been added. The melamine was being added by unscrupulous operatives somewhere in the milk supply chain, to artificially boost the nitrogen content of the product, and so spoof higher protein levels than are actually present.

Subsequently, lists of contaminated products appeared in the media and on the web and as the melamine scandal widened, the Chinese government issued an apology and promised to crack down on the problem.

However, with news this week that batches of eggs imported into Hong Kong from China have tested positive for melamine, which is suspected of causing kidney problems, it now appears that the compound is being added routinely to animal feed in China. According to the BBC, this news has been released into the Chinese state media by a government realising it has far less control over food standards that it ought to have.

The melamine scandal is not new. It is essentially an open secret in China that the compound is added to all kinds of foods, particularly animal feed and pet food to artificially inflate the protein readings at the so-called quality control stage. Melamine was at the heart of the petfood scandal in 2007, but that was simply the first time that the West learned of the problem. It seems obvious that melamine could have been in the food chain much longer than that.

But, whether the open secret of melamine in the food supply is actually as serious a problem as the media would have us believe is down to toxic dose. AP quotes Peter Dingle, a toxicologist from Murdoch University, Perth, Australia, who says that aside from the tainted baby formula that killed at least four Chinese infants and left 54,000 children hospitalized in September, it is unlikely humans will get sick from melamine. The amount of the chemical in a few servings of bacon, for instance, would simply be too low, he said. But he is not recommending that the practice continue unchecked. China should have cracked down sooner on feed companies he and others have said.

However, if the melamine open secret is as big as it appears from the outside, it is unlikely to be stopped any time soon, particularly because of the heirarchical government system in China. “It could take five or even 10 years” before some companies stop adding the chemical to food products, Jason Yan of the US Grains Council is quoted by AP.

Four infants in China have died and at least 53,000 are reportedly ill, many seriously so, having been fed milk powder contaminated with the industrial chemical melamine. A three-year old girl in Hong Kong is also ill, but has now been released from hospital, she was the first reported case outside mainland China. Major formula milk producer Nestle says none of its products in China has been contaminated with melamine, although the Hong Kong government says it has found the contaminant in the company’s milk formula.

I guess it’s no surprise that this scandal has emerged after, rather than before or during, the Olympic Games, but that is not something that would be peculiar to China. Governments the world over try to manage bad news and China certainly does not have a monopoly on cover-ups. If melamine is the primary contaminant, then regardless of claims that other compounds may be present, long-term use (six months or so) would be enough for this toxic compound to accumulate in an infant and lead to toxic effects such as kidney stones. The LD50, or acute toxic dose is not entirely relevant if an infant is being fed contaminated milk day after day. Incidentally, LD50 is a measurement per kilogram of body mass, so it is not higher for people than it is for rats, although it may be different because of differences in our body’s biochemistry.

I used to use an analytical instrument when I worked part-time in quality control in a milk-processing plant during my early post-student days. The machine could give you an almost instantaneous printout of fat, protein and sugar levels in the milk passing through the dairy. Those in QC also had to look at the milk for colour and quality and smell and taste it to check for taints (from pipe disinfectants, bacterial action, or contaminants). Indeed, one of the qualifications for the job was to have a palate sensitive enough to detect phenolic (smoky) compounds down to a few parts. It would usually have been quickly apparent if there was a problem with any incoming milk supply and I cannot see how others in the supply chain in China were not duplicitous in this conspiracy.

There could, of course, be other contaminants, I alluded to that in the original melamine in milk post. If someone is unscrupulous enough to add melamine to baby milk to falsify protein levels, then there’s no reason to think that they would use expensive chemically pure material. This would go some way to answering one of the questions asked by a commenter on the original post. Apparently, the Chinese government reported findings 2565 ppm or 0.25% of melamine in Sanlu’s milk powder. The cost of melamine is relatively high, so what would be the economic justification for such an irresponsible act if it were only increasing the apparent protein level by 1.2%?

The melamine may have been obtained from low-quality sources that are themselves contaminated with other toxic compounds, or it may be high-quality melamine, but stolen to order at some point in the supply chain? It has been suggested that other contaminants may be urea and aminopterin, but I have not seen any official note on that anywhere.

Melamine decomposes on heating, so one commenter on the original post was curious as to how does melamine survive the pasteurization and evaporation processes without decomposition used to make milk powder from raw milk.

Apparently, melamine has been mentioned in dispatches across China for more than 15 years, why is it that a pet food scare in 2007, and now this infant formula milk scandal are the only times that the western media has covered the problem?

It is becoming apparent that contaminated baby formula is not the only problem. Milk, ice cream, yoghurt, confectionery such as chocolates, biscuits and sweets, as well as any foods containing milk from China have been banned from import into Singapore after the country’s agri-food and veterinary authority found melamine in imported samples. Similarly, Taiwanese authorities seized imported products after notification of contamination from Beijing earlier this month. Japan has recalled various products. Canada’s Food Inspection Agency has warned citizens not to eat a dessert – Nissin Cha Cha Dessert – imported from China that has been found to be contaminated with melamine. The authorities in the Philippines are currently testing.

It is curious, but perhaps not surprising, that the Chinese authorities say not a single hospitalisation case has any connection with contaminated milk. Fonterra, parent company of milk producer Sanlu which is at the centre of the scandal says the whole debacle is one of sabotage and that there is no point in the production process at which melamine could have been added. Fonterra chief executive Andrew Ferrier claims an unknown third party put the banned chemical melamine into raw milk supplied to Sanlu. However, the company new about the contamination on August 2, just ahead of the Olympic Games, and claims that Chinese regulations prevented it from going public at the time.

RELATED: Melamine in Milk, this was the original item I posted on the melamine in milk scandal. I’ve also added an UPDATE: Milky Melamine, dated 2008-09-29.

UPDATE: Melamine Milk Update, January 22, 2009

Sciencebase will be keeping you updated on the melamine scandal with opinion from the experts and the latest news on the story as it unfolds.

Several thousand babies in China became ill, having apparently suffered acute kidney failure, with several fatalities, having been fed formula milk allegedly contaminated with the industrial chemical melamine. The toll is far higher than was previously admitted by the Chinese authorities, according to the BBC. Click here for a list of melamine contaminated products.

One manufacturer recalled all of its powdered milk products in China’s north-west province of Gansu. However, twenty-two brands of milk powder were quickly identified as containing melamine. “The majority of afflicted infants ingested [the] milk powder over a long period of time, their clinical symptoms showed up three to six months after ingesting the problematic products,” Health Minister Chen Zhu told Bloomberg Asia.

Allegedly, someone in the supply change, milk supplier or manufacturer, was adding melamine to the milk formula to artificially inflate the reading for protein levels. Formula milk was not until now tested for melamine, because regulators did not suspect this ingredient might be added. But, it turns out that melamine in the food supply is China’s big open secret.

So, what is melamine and how does it spoof the protein levels in baby formula milk?

Melamine is an organic compound, a base with the formula C₃H₆N₆. Officially it is 1,3,5-triazine-2,4,6-triamine in the IUPAC nomenclature system (CAS #108-78-1). It is has a molecular mass of just over 126, forms a white, crystalline powder, and is only slightly soluble in water. It is used in fire retardants in polymer resins because its high nitrogen content is released as flame-stifling nitrogen gas when the compound is burned or charred.

Indeed, it is this high nitrogen level – 66% nitrogen by mass – in melamine that gives it the analytical characteristics of protein molecules. Melamine can also be described as a trimer of cyanamide, three cyanamide units joined in a ring. It is described as being harmful according to its MSDS sheet: “Harmful if swallowed, inhaled or absorbed through the skin. Chronic exposure may cause cancer or reproductive damage. Eye, skin and respiratory irritant.” Not something you would want in your infant’s milk. However, that said, the toxic dose is rather high, on a par with common table salt with an LD50 of more than 3 grams per kilogram of bodyweight.

Previously, melamine was found in exported pet food last year and blamed for killing thousands of cats and dogs in the US. Bloomberg also reports that analysis of samples of ice cream produced by one company have also revealed the presence of melamine. Regardless of crushing inflation and legislative pressure, there is no excuse for the adulteration of food in this way. Diluting a product, the previous approach, is highly unethical and can lead to malnutrition, but straight poisoning is tantamount infanticide. This is also not the first time that Chinese consumers have faced problems with milk powder. In 2004, more than a dozen children died having been fed formula with minimal nutritional content.

But, if melamine has low toxicity (hat tip to commenter Barney) then what is it that has poisoned thousands of babies in China and why has this scandal occurred? Well, LD50, the toxic dose issue, tells us something about acute exposure not the apparent six-months’ worth of accumulated exposure these babies have suffered. Chronic exposure to melamine can lead to bladder or kidney stones and even bladder cancer and as we have learned, acute kidney failure. Health problems such as these can land you in the hospital. Most treatments cannot be given at home, therefore you will not have the comfort of your couch or bed. Many hospitals do not have the luxury of offering ergo mattresses to their patients.

The melamine in milk headlines also ignore the fact that the compound added to the milk may not be pure. There is no reason to imagine that those unscrupulous enough to add a toxic compound to baby formula milk would worry about contaminants, such as cyanuric acid, that might be found in the raw material. Indeed, even if melamine toxicity were not an issue and truly was an inert substance added to spike the protein readings in quality control tests, then any one of the impurities associated with rough melamine manufacture may be a major cause for concern.

UPDATES: A melamine apology from the Chinese premier, Melamine Scandal Widens and Milky Melamine, melamine and kidney failure.