Melamine, an industrial chemical used in everyday items such as cooking utensils, plates, paperboard and industrial coatings, can apparently seep into food when it is heated, the study said.

In two separate tests, researchers from Kaohsiung Medical University and Kaohsiung Municipal Hsiao-Kang Hospital in Taiwan served a dozen participants about two cups of hot noodle soup in melamine bowls and ceramic bowls. After participants ate out of the melamine bowls, the levels of melamine in their urine peaked six hours later, up to about 8 parts per billion, before tapering off later in the day. Those who ate out of ceramic bowls had on average less than 2 parts per billion. Researchers suggested some of the melamine detected after eating from the ceramic bowl was actually leftover melamine from first eating from the melamine bowl.

A person can have up to 2,500 parts per billion of melamine in their blood before it poses a health risk, according to the Food and Drug Administration.

It was unclear if the amount of melamine measured during the study was significant, researchers said, but they cautioned that long-term exposure to the chemical could pose health risks.

The World Health Organization's International Agency for Research on Cancer concluded in 1999 that there was sufficient evidence that melamine can act as a carcinogen in animals, but inadequate evidence it acted the same in humans.

Overall, the FDA considers the amount of melamine the public is typically exposed to from tableware is safe. Still, the agency cautions consumers not to heat food or drinks in melamine-based dinnerware in a microwave.

Melamine was the chemical behind a 2008 health scare in China, when melamine-tainted baby formula killed six children and sickened 300,000 others. There were up to 2.5 million parts per billion of melamine in those samples.