Melamine Bowls Release Chemical in Hot Soup

A steamy bowl of soup on a wintry day is a true comfort, but you might want to make sure your hot soup is served in a ceramic or glass bowl instead of plastic.

A small but unsettling study finds that those colorful hard, plastic bowls made from melamine release a chemical when filled with hot food, increasing the risk of kidney stones.

In a pilot study published in the journal JAMA Internal Medicine, researchers in Taiwan found that volunteers who ate hot soup from melamine bowls excreted eight times as much melamine in their urine afterward when compared with those who ate their soup from ceramic bowls, Time magazine reported.

Melamine exposure remains common, the researchers wrote, even after the 2008 scandal in China when melamine powder added to thicken baby formula caused six deaths and 50,000 hospitalizations.

Continual exposure to low doses of melamine increases the risk of kidney stones in both adults and children, the scientists wrote, and one source of that exposure is the popular, inexpensive dishware.

Melamine, Time reports, has been used to make unbreakable plastics since the 1930s. It is approved by the Food and Drug Administration (FDA) for making plastic products, though not as an additive in human or animal food. (Melamine powder was also the culprit in a 2007 tainted-pet-food outbreak.)

The Taiwanese researchers had 12 healthy volunteers consume about 16 ounces of hot soup from either a melamine bowl or a ceramic bowl. Urine samples were taken before eating and then every two hours for up to 12 hours after. After a three-week "washout period" to clear their systems, the groups were reversed; those who had eaten from a melamine bowl were given a ceramic one and vice versa.

The researchers reported that after 12 hours, total melamine excretion in urine was 8.35 micrograms for those using melamine bowls and 1.31 micrograms for those using ceramic bowls.

Whether this small amount is enough to cause harm is unclear, the researchers said, but people should be aware that this kind of dishware "may release large amounts of melamine when used to serve high-temperature food," which is a cause for concern.

Microwaving food using melamine dishes may have similar effects. The FDA recommends that "foods and drinks should not be heated on melamine-based dinnerware in microwave ovens. Only ceramic or other cookware which specifies that the cookware is microwave-safe should be used. The food may then be served on melamine-based tableware."

Photo:  Andrea_Nguyen /flickr