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Melamine Contamination

Authored by: Dr. Kim Baughman, Director of Development, Microbac Laboratories, Inc.

The contamination of milk products with melamine is the second serious issue with this chemical in the past year.  The initial problem was with pet foods and resulted in deaths and injury to many pets.  Officials believe melamine was added to boost the reading obtained in a quick protein test. 

The standard test for protein does not actually measure protein, but rather measures the amount of nitrogen in the sample and it is assumed all of the nitrogen in the sample came from protein.  This is a valid assumption for a food sample, but apparently, some dairies in China have deliberately added melamine to their milk.  Because melamine is rich in nitrogen (close to 66%), this results in a higher apparent protein value, which allows for a higher price for the milk.

The issue has become significant in Asia, resulting in the illness and even death of infants.  Several Asian countries have implemented requirements for testing of imported milk or products containing milk.  The issue has been slower to impact the United States.  However, milk and milk powder are used in many products, and melamine has been found in limited samples, including infant formula and candy samples sold in the U.S.  On November 13, 2008, the FDA imposed a detention order on dozens of foods being imported from China.  This will require that they be tested before being allowed in the country.

Melamine is primarily toxic to the kidneys.  It causes the formation of cyanuric acid crystals in the kidneys or in the renal tubes.  It has been particularly toxic to children, partly because they consume more of these products per body weight, and partly because the crystals can cause a greater degree of blockage in their small kidney tubes.  This was the same mechanism responsible for the deaths of pets in the episode last year.

As importers continue to face new food safety issues, testing methods are becoming more critical.  The FDA has published an interim method for the determination of melamine in a variety of products.  The method uses gas chromatography with mass spectrometric detection.  This is a common instrument in most food analysis laboratories.  The FDA has also published a method for the determination of melamine in fish.  This method uses HPLC/MS/MS, which is a more specialized instrument.  Both of these methods can be adapted for determining melamine in a variety of products.

As of November 28, 2008, the FDA has set a limit of 1 part per million as the safety threshold for infant formula sold in the United States.  However, if the product also contains cyanuric acid, no safe limit has been established.

Microbac Laboratories Inc. performs a full range of food testing, including contaminants, such as melamine.  We prepare FDA-detention data packages where required.  We also perform analysis for nutrition labeling and microbial contamination.

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For more information, contact:
Dr. Kim Baughman, Director of Development, Microbac Laboratories, Inc. kbaughman@microbac.com

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