Melamine is a synthetic chemical made up of carbon, nitrogen and hydrogen. It is widely used in making plastics, adhesives, countertops, dishware and whiteboards. It is also used in some pesticides and fertilizers.
As melamine is rich in nitrogen, it has been used in China to falsely increase test results for protein levels in certain foods.
In 2007, pet food made in China was contaminated with melamine. This led to the deaths of dogs and cats across the United States and Canada. Some of this pet food was also used as feed for farm animals and fish in North America.
In 2008, melamine was purposely added to milk and powdered infant formula in China. More than 51,900 people were hospitalized as a result of this contamination. The effects included urinary problems, blockage of tubes in the kidneys, and kidney stones. Six related deaths have been confirmed.
Melamine contamination has since been discovered in infant formulas and other products from China containing milk. These include liquid milk, frozen yogurt, biscuits, candies and coffee drinks. No illnesses related to melamine have been reported in Canada.
Melamine has also been found in eggs in China. This was most likely from chicken feed contaminated with melamine. Canadian authorities have ensured that products such as meat, eggs, dairy, and fish meet our regulatory standards. No reports have been made of melamine contamination in these products.
Our bodies do not use melamine. It quickly passes out of the body in urine. Melamine does not build up in our bodies over time.
Melamine is not approved for use as a food additive. However, we may eat or drink trace amounts indirectly through materials that are in contact with food. For instance, melamine is approved for use as an adhesive in certain juice and milk containers. Since melamine is widely used in plastics including dishware, very low levels may be found in many foods if sensitive test methods are used to test for it.
Levels resulting in foods from these ‘allowed’ uses of melamine are vastly lower than levels from the intentional contamination in China. Eating foods with trace amounts of melamine does not present a risk of kidney damage to adults, children or infants.
A recent expert review done by the World Health Organization set limits of melamine to protect against harmful effects. These are 1 mg/kg (parts per million) in powdered infant formula and 2.5 mg/kg (parts per million) for other foods. In contrast, the intentional addition of melamine to infant formula and other foods in China resulted in levels as high as 6196 mg/kg. This is over a thousand times higher.
Compared to many other substances, melamine’s toxicity is actually quite low. When measuring and comparing the poisoning potential of a given substance, a value known as the LD50 is used. LD stands for ‘lethal dose.’ The LD50 represents the amount of a substance, given all at once, that causes the death of 50 per cent of a group of test animals. Using the LD50, melamine is as toxic as common table salt. In other words, it would take a very large amount of melamine to cause an acute poisoning.
However, the amounts purposely added to foods recently in China were high enough to damage health even after relatively little exposure.
Melamine becomes a concern when it is consumed in large amounts. Animal studies show that at high doses and over a long exposure time, melamine can cause bladder irritation and bladder stones. It is also linked with increased numbers of bladder tumours in rodents. However, there is not enough evidence to make any conclusions about human cancer risk.
Taking in melamine along with cyanuric acid gives more cause for concern. Together, melamine and cyanuric acid may form crystals that eventually block tubes in the kidneys. This leads to kidney failure, and sometimes to death. Again, this would only occur at very high dose levels and does not apply to the low levels to which the average person is exposed.
n the case of the contaminated infant formula in China, the high levels of melamine alone were enough to produce kidney stones.
The Canadian Food Inspection Agency's website is a good source. It also maintains an updated list of recalled food products:
You can subscribe to receive e-mail recalls through the same website by clicking on the E-mail Notification Services’ option under the title ‘Quick Links.’
Health Canada has confirmed that all major Canadian makers and importers of infant formula do not use any milk ingredients from China. As well, infant formula made in China is not approved for sale in Canada.
Other products with milk ingredients from China are being tested to ensure that melamine levels do not exceed standards set by Health Canada. Any high risk product will be recalled and the public will be notified. Canadian standards continue to be updated to reflect new evidence about melamine. Testing is being done to ensure compliance with the limits.
The Public Health Agency of Canada has advised that you should not consume a recalled product. Throw it away or return the product to the place of purchase. You may also contact the Canadian Food Inspection Agency at 1-800-442-2342.
If you travel to China, take all formula and milk products with you. Avoid giving your baby infant formula or milk products that are made in China. Keep in mind that ingredients made from milk include whole milk powder, non-fat milk powder, whey powder, lactose powder and casein. If you must use such products while in China, speak to a local public health authority in your area to confirm which products are free of melamine.
If you have any further concerns, consult your health care provider.