The Why Files The Why Files --

Food imports: How safe?

Plastic 'n gravy: groovy Fido feed?
In March, 2007, the largest pet-food recall in U.S. history started after pet food containing the chemical melamine started killing cats and dogs. A reported 60 million containers of pet food, sold under scores of brand names, were contaminated with a compound normally used to make plastic and fertilizer.

Two adorable pups chow down, noses buried in silver bowls
Earlier this year, a massive contamination of pet food with melamine killed thousands of cats. The contaminant, melamine, is normally used in plastic and fertilizer. Fortunately, these puppies didn't get the tainted food. ©S.V. Medaris

White chest of drawers strewn with nicknacksAll had been made by the Canadian firm Menu Foods, which had blended Chinese wheat gluten contaminated with melamine into its many products.

The estimates of pet deaths ranged past 5,000, but no authoritative death toll has yet been announced.

Melamine is used to coat particle board with an attractive, impervious coating. Melamine also fools protein detectors, which explains its appearance in many Chinese food ingredients, including soy protein and wheat gluten. Sadly, it destroys kidneys, and mammals die.

Food is not supposed to contain melamine, but on April 30, The New York Times reported that manufacturers of various foods -- for humans and animals -- routinely bought it anyway (see #8 in the bibliography). Why? Because the chemical is cheap, and the nitrogen it contains can fool protein tests:

"... two animal feed producers explained in great detail how they purchase low-grade wheat, corn, soybean or other proteins and then mix in small portions of nitrogen-rich melamine scrap, whose chemical properties help the feed register an inflated protein level. 'People use melamine scrap to boost nitrogen levels for the tests,' said the manager of the animal feed factory. 'If you add it in small quantities, it won't hurt the animals.'"

A grocery list written in blue, top and bottom faded outAs of July 2, 2007, the FDA posted this long list of melamine-contaminated pet food brands. Better known for making countertops and fertilizer, the compound was carried in wheat gluten used to make as much as 60 million cans and bags of pet food. List: FDA

Much like the diethylene glycol substitution, melamine represents "the almighty dollar talking," says Steve Ingham, a professor of food science at the University of Wisconsin-Madison. "It's this longstanding game to figure out what analytical method is used to analyze a food or commodity ... and then game it somehow with a cheaper ingredient."

Years ago, Ingham says, he worked on methods to detect adulteration in orange juice, honey and maple syrup. "It's a kind of arms-race mentality. As scientists, we publish our methods, and the bad guys will figure out the method and try to beat it. It's like in sports, if you know the drug test ... you will figure out how to get around it."

Melamine: It's what's for dinner
And how would you dispose of 60 million cans of recalled, contaminated pet food? Simple: Feed it to pigs and cattle. We are not making this up, but not to worry. The FDA and the U.S. Department of Agriculture agree that the melamine concentrations in the animal feed were so low that a person would have to gobble 800 pounds of meat per day to incur a reasonable risk.

And this may not be the last word on melamine contaminated food. On July 1, a manufacturer of animal-feed ingredients announced a recall of a product used to bind pellets of animal feed. cutest kitty everTembec Chemical Group had added about 3 percent melamine to its product, which is used in feed for fish, shrimp, cattle and other animals. The melamine concentrations in feed ranged from 50 parts per million in cattle feed to 465 ppm in shrimp feed.

Pets and people are equally unsuspecting when it comes to food safety. Courtesy ©Megan Anderson

This leads us to wonder what else is contaminating our food, but it's much harder to test for a random contamination than to test for a chemical we already suspect is in the food.

Toxic products: Par for the course?


Megan Anderson, project assistant; Terry Devitt, editor; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

©2022, University of Wisconsin, Board of Regents.