The Chinese melamine scandal of 2008 pointed out the vulnerability of the global food supply. Be vigilant about where your food is coming from. Or better yet, become a locavore!

In September 2008, the world was shocked at the sight of little babies in China attached to dialysis machines as they fought for their lives. Yet, the news of contaminated milk formula did not gain much attention until it was realized that the melamine problem was not just restricted to China but had actually spread globally.

Melamine is an organic compound with the official IUPAC name of 1,3,5-triazine-2,4,6-triamine and the chemical formula of C₃H₆N₆. It is a solid white-colored base, and is odorless. It is slightly soluble in water, stable, and not easily biodegradable. Melamine is an industrial ingredient used to manufacture different kinds of products. It is used in combination with formaldehyde in the production of plastics and cleaning products. It is also combined with other compounds in the manufacture of fire retardants, pesticides, fertilizers, extra-strong concrete.

You may not be aware of it, but we are exposed daily to melamine. Many things in our home have been manufactured with the use of melamine, from Formica counter tops, to certain fabrics, to plastic kitchenware (melaware). Also, people working in many factories worldwide are exposed daily to melamine. It is estimated that over 100,000 workers are exposed to occupational melamine annually.

Is melamine toxic? It depends.

Like most industrial chemicals, toxicological tests on melamine have been performed using animals to determine its potential toxicity to humans. According to the Material Safety Data Sheet (MSDS), melamine is "Harmful if swallowed, inhaled or absorbed through the skin. Chronic exposure may cause cancer or reproductive damage. Eye, skin and respiratory irritant".¹

The toxicity of melamine, however, is low. To be “poisoned” by melamine, as determined by the so-called LD₅₀, which is the lethal dose that will kill 50% of animals tested, is 3 g per kg of body weight (source: WHO) And studies cited in the Hazardous Substances Data Bank (HSDB), “ indicate that melamine itself does not seem to be important industrial hazard except if decomposed by heat.” Allergic and irritative dermatitis have been observed to result from occupational exposure to melamine but no permanent injury due to toxicity has been reported.²

But, what is more important is chronic exposure to melamine. In the 2008 melamine contamination scandal, acute toxicity was not the issue that caused the health problems because nobody would voluntarily swallow big amounts of melamine. What made the babies ill was chronic or subchronic toxicity, e.g. taking in significant amounts of melamine regularly for long periods of time.

The toxicity of melamine increases when combined with another compound called cyanuric acid.

Cyanuric acid, theoretically non-toxic, is present in food additives for animal feeds and in water disinfectants. Human exposure to cyanuric acid may be through swimming pool waters, drinking water, and fish. The combination of these two compounds can lead to acute toxicity, as it produces melamine cyanurate, a toxic substance in the form of insoluble crystals that then accumulated in vital organs, especially the kidneys, forming renal crystals or kidney stones that block kidney tubules.³

According to the Center for Disease and Prevention (CDC), “Infants may be more affected than other people because formula is their primary food source and they therefore consume more melamine per unit of body weight than older children and adults who consume a variety of foods”.⁴

However, there are significant gaps in our knowledge of melamine and its effect on our body. The safety/risk assessment conducted by the U.S. FDA does not give any clear answers. According to its FAQs about melamine, the regulatory body “is currently unable to establish any level of melamine and melamine-related compounds in infant formula that does not raise public health concerns…In food products other than infant formula, the FDA concludes levels of melamine and melamine-related compounds below 2.5 parts per million (ppm) do not raise health concerns”.⁵

Here are some animal studies' results:

• Melamine caused the formation of calcareous deposits in the kidneys of female rats after 13 weeks of feeding melamine-containing food (WHO).
• Melamine was found to cause tumors in the urinary bladders of male rats fed diets with melamine for 103 weeks (IARC).⁶
• Melamine and cyanuric acid together caused renal toxicity in cats, pigs, and fish. The study concluded that “although melamine and cyanuric acid appeared to have low toxicity when administered separately, they induced extensive renal crystal formation when administered together. The subsequent renal failure may be similar to acute uric acid nephropathy in humans, in which crystal spherulites obstruct renal tubules”.⁷

So, how did melamine get into the world's food supply?

Food products are tested for protein content by measuring nitrogen content. And interestingly the chemical composition of melamine has high nitrogen content. It is speculated that manufacturers mixed melamine in milk formulas to increase the protein content of their products.

And there is no easy way to test for melamine contamination! Researchers at the University of Missouri used surface enhanced Raman spectroscopy and high performance liquid chromatography to detect melamine in gluten, chicken feed, and other processed foods. In kidney tissues of animals, melamine is detected post-mortem by the use of liquid chromatography/tandem mass spectrometry.^8,9

This was not the first time that melamine was used deliberately as a protein content enhancer. In 2007, many cats and dogs died of kidney failure as a result of the formation of renal crystals or kidney stones. The cause of the renal toxicity was traced to melamine which was detected in pet food. Melamine-cyanuric acid cocrystals were found in the animals’ kidneys and the case was well-publicized.¹⁰

The 2008 melamine scandal was more shocking and the most deadly so far.

Three babies were killed and upwards of 300,000 children in China and Hong Kong were sickened by melamine contamination. It is highly unlikely that the perpetrators who tainted the baby formulas were unaware of the hazards of melamine consumption. So, here's the melamine story.

September 11, 2008 Fourteen babies in the Chinese province of Gansu were reported to be suffering from kidney stones, a very rare occurrence in young children. The suspected cause was the milk formula they were drinking. More and more cases of ill babies were reported all over China. The milk powder in question was manufactured by the Sanlu Group.

September 12, 2008 The U.S. Food and Drug Administration issued a health information advisory on infant formulas. The advisory “is to assure the American public that there is no known threat of contamination in infant formula manufactured by companies that have met the requirements to sell infant formula in the United States… The following manufacturers have met the necessary FDA requirements for marketing milk-based infant formulas in the United States: Abbott Nutritionals, Mead Johnson Nutritionals, Nestle USA, PBM Nutritionals, and Solus Products LLC”.¹¹

September 13, 2008 Tests showed that the milk powder which caused the illness contained melamine. Sanlu ordered the recall of 700 tons of powdered milk.

September 15, 2008 Fonterra, the New Zealand dairy company and venture partner of Sanlu, declared that melamine contamination of their products is due to sabotage.

September 23, 2008 The director of the Chinese agency General Administration of Quality Supervision, Inspection and Quarantine resigned as investigations showed that the melamine contamination is quite widespread. Tests showed that milk products of up to 22 dairy producers were contaminated with melamine. This made sabotage a very unlikely explanation.

September 24, 2008 The European Food Safety Authority (EFSA) issued a statement to advise European consumers not to exceed the tolerable daily intake (TDI) of 0.5 mg/kg body weight of products such as chocolates and biscuits that could potentially contain melamine.¹²

September 26, 2008 The New Zealand Food Safety Authority found melamine in China’s most popular sweet White Rabbit Creamy Candies.¹³

October 2, 2008 The problem spread to Europe. Chinese candies contaminated with melamine were found in an Asian supermarket in Germany. There were also reports of contaminated food products in Belgium and the Netherlands.¹⁴

October 8, 2008 The Canadian Food Inspection Agency (CFIA) issued a warning against the consumption of Sherwood Brands Pirate’s Gold Milk Chocolate Coins which tested positive for melamine. It was not clear how the contamination occurred.¹⁵

October 14, 2008 The numbers of ill babies rose up to tens of thousands. Eighty percent of those affected were below the age of 2. Four cases proved to be fatal. China also recalled not only powdered milk but also liquid milk manufactured during the last couple of months.

October 27, 2008 Hong Kong found excessive amounts of melamine in eggs coming from mainland China. Officials suspected that the contamination came through melamine in the chicken feeds. They have ordered testing of all animal feeds and poultry products from the mainland. “Hong Kong has imposed a limit on melamine use in foods, restricting it to no more than 2.5 milligrams per kilogramme. Melamine found in food meant for children under three and lactating mothers should be no higher than one mg per kg”.

November 14, 2008 The U.S. FDA issued a nationwide alert warning for Chinese import food products. Food Standards for Australia and New Zealand issued a similar warning in early December.

December 4, 2008 The U.S. FDA tried to assure the American public that American-produced formulas are safe from contamination. “To date, FDA tests have found extremely low levels of melamine in one infant formula sample and extremely low levels of cyanuric acid in another. The levels were so low (well below 1 ppm) that they do not pose a health risk to infants.” The FDA made public the test results on domestic infant formula. Good Start Supreme Infant Formula with Iron from Nestle contained very low amounts of melamine. In addition, cyanotic acid was found in one type of Enfamil from the manufacturer Mead Johnson.

The Bottom Line

The 2008 melamine scandal points out how dependant we are on the global food system and how easy it is for it to be contaminated. Since there is no simple test to detect melamine contamination in our foods we have to depend on the regulatory agencies.

In the meantime be vigilant about what you buy and consume, especially products consumed by children in large quantities such as milk and milk products, chocolates, sweets, and biscuits. And make it a habit to determine where your food is coming from. Or better yet, become a locavore.

Published January 1, 2009, updated June 06, 2012

References

1. Material Safety Data Sheet, Melamine
2. Hazardous Substances Data Bank (HSDB), TOXNET
3. Melamine and Cyanuric acid: Toxicity, Preliminary Risk Assessment and Guidance on Levels in Food, WHO updated 30 October 2008
4. Melamine in Food Products Manufactured in China, Centers for Disease Prevention and Control
5. Melamine Contamination In China, U.S. FDA, Updated January 5, 2009
6. IARC Monographs on the evaluation of the carcinogenic risk of chemicals to humans, Vol:73 (1999) pp 329-38
7. Reimschuessel R, Evaluation of the renal effects of experimental feeding of melamine and cyanuric acid to fish and pigs, Am J Vet Res. 2008 Sep;69(9):1217-28
8. Lin M, Detection of melamine in gluten, chicken feed, and processed foods using surface enhanced Raman spectroscopy and HPLC, J Food Sci. 2008 Oct;73(8):T129-34
9. Filigenzi MS, Diagnostic determination of melamine and related compounds in kidney tissue by liquid chromatography/tandem mass spectrometry, J Agric Food Chem. 2008 Sep 10;56(17):7593-9. Epub 2008 Jul 25
10. Dobson RL, Identification and characterization of toxicity of contaminants in pet food leading to an outbreak of renal toxicity in cats and dogs, Toxicol Sci. 2008 Nov;106(1):251-62. Epub 2008 Aug 9
11. FDA Issues Health Information Advisory on Infant Formula, U.S. FDA, September 12, 2008
12. Statement of EFSA on risks for public health due to the presences of melamine in infant milk and other milk products in China, EFSA, 24 September 2008
13. Melamine in foods from China, Food Standards Australia New Zealand
14. Melamine contamination of dairy products in China – public health impact on citizens of the European Union, EuroSurveillance, Oct 2, 2008
15. Sherwood Brands Pirate's Gold Milk Chocolate Coins may be Contaminated with Melamine, CFIA, 8 October 2008