CABI Blog

Melamine contamination of pet food in North America is more than two months old story now, but the end of crisis is still nowhere in sight. Thousands of dogs and cats that have eaten contaminated foods have suffered kidney problems or died, although there are somewhat conflicting reports as to the actual numbers of pets that were affected (see my previous blog). The US Food and Drug Administration (FDA) has identified melamine and melamine-related compounds in a consignment of wheat gluten and rice protein concentrate imported from China and used to make many brands of pet food as the main culprit.  Chinese suppliers are suspected of intentionally adding melamine to make it appear that their products were higher in protein content, which translates to a higher price. Melamine has no nutritional value but is about two-thirds nitrogen by weight, and nitrogen levels are often used as crude indicators of protein content in food commodities. It has been know for a long time that feed manufacturers may intentionally add melamine to animal feeds as a paper by Cattaneo & Ceriani (1988) demonstrated. The abstract of this paper can be seen in Animal Science database.

The FDA’s findings triggered one of the largest pet food recalls in U.S. history. Since 16 March, 18 companies have recalled more than 5,600 pet food products. The recalls, however, do not seem to have come to an end. The latest addition to the recall list includes the dry dog food Nutra Nuggets, manufactured by Diamond Pet Foods of Meta, Missouri, which have tested positive for melamine and caused kidney problems in at least four dogs in California.

Weeks after contaminated Chinese pet food ingredients affected thousands of dogs and cats in the United States and with contamination spreading to meat and fish supplies, the US feed manufacturers are not entirely faultless either. There is no satisfactory explanation yet how scraps of contaminated pet food ended up being used to produce feed for pigs, poultry and fish in the USA, nor how the contaminated feeds were distributed to farms in a number of states and given to several thousand pigs and millions of chickens and fish. This enabled melamine to enter the human food chain in the USA weeks after it had been known of melamine contamination in pet foods.

Meantime, China faces growing international pressure to prove that its food exports are safe to eat. Some of the biggest U.S. food companies are now lobbying the US government to pressure China to increase its food safety measures. In addition, Menu Foods and other pet food manufacturers have announced this week that it would no longer source vegetable proteins such as wheat gluten or rice protein concentrate from China until those ingredients are deemed safe. At stake for China is more than $30 billion a year in food and drug exports to Asia, Europe and North America. Managers of two companies accused of exporting the tainted ingredients have been detained and police have opened cases against them. China’s main food safety regulator said that an investigation into the pet food scandal had verified the safety of other exporters of rice protein concentrate and wheat gluten.

In related developments, two months after pet food contamination in North America, Wal-Mart Stores, the largest U.S. retailer, announced a recall of baby bibs made in China after some of those bibs tested positive for high levels of lead. Furthermore, authorities in the Dominican Republic and Panama have ordered a recall of the Chinese toothpaste brands this week, after learning that they contained diethylene glycol, a chemical commonly used in antifreeze and brake fluid. These events could further damage China’s reputation as an exporter.

Unfortunately, contaminated food commodities are not the only route for melamine to enter the food chain as shown by the recent FDA tests that have detected melamine in a sample of imported Chinese catfish, examined on behalf of the Arkansas Department of Health and Human Services. Although officials are downplaying the health hazard of melamine, this latest finding indicates that the human food supply is more widely contaminated than previously acknowledged, and this will do little to reassure consumers, not only in the USA, but also in China and elsewhere, who are already sceptical about their food safety.