Why was melamine in milk in China?

Q What is melamine, and how does it get into milk? Do we have to worry about it getting into milk here?

A Melamine is a powder that's used to make plastic found in floor tiles, kitchen countertops and such. Melamine has never been discovered in the U.S. milk supply or in dairy products produced in this country, said Kim Polzin, spokeswoman for the Midwest Dairy Association/Midwest Dairy Council. Look for the "Grade A" mark on the package to know it's safe, she added.

Melamine doesn't belong in food -- for humans or pets. It affects the kidneys and can lead to renal failure and death. (You might remember that melamine-tainted pet food was linked to the deaths of dogs and cats last year.)

The Food and Drug Administration (FDA) in November blocked the importation of Chinese milk products and began checking products that were here. That's how it discovered melamine in cookies for sale in Minnesota. The cookies, made in Vietnam and sold under the Wonderfarm brand, were recalled.

Recently, trace amounts of melamine were found in some U.S. baby formula, according to the FDA. However, levels were so low that the formula poses no health threat and is safe to use. The FDA said the melamine may have leached from the plastic lining in cans or from the manufacturing process, and was not added intentionally.

The addition of melamine to milk in China has to do with what the FDA calls the country's "vast and fragmented food-processing industry." Melamine is high in nitrogen and mimics protein in tests, so adding melamine can make it appear that there is more protein in milk than there actually is. Spiking milk is not new there, according to a Wall Street Journal report. Farmers in one Chinese province, according to the story, "say 'protein powder' of often-uncertain origin has been employed for years as a cheap way to help the milk of undernourished cows fool dairy companies' quality checks. When the big companies caught on, some additive makers switched to toxic melamine."