Melamine is a chemical used in plastics, adhesives, countertops, and dishware. It has been shown to cause cancer or reproductive damage. In 2008, melamine-tainted powdered infant formula was found in China, which killed 6 children and sickened thousands more.
A study in the JAMA Internal Medicine found that people who ate out of melamine bowls had a much higher level of melamine in their urine compared to the ones who used ceramic bowls, showing that melamine was getting into the body when using these bowls.
The FDA considers the amount of melamine in dishware to be safe. However, long term exposure to the chemical may have negative health consequences. Make sure never to heat food on this melamine dishware in the microwave in order to try to keep your exposure to a minimum.