McDonald’s has voluntarily recalled approximately 12 million Shrek Forever After collectible glasses (above)—sold since May 21 at the chain’s U.S. restaurants—because they contain high levels of cadmium.

The premium incentive (aka McBribery) was designed to accompany the Shrek Happy Meal promotion (right), which launched last month as a tie-in with the new Shrek 3D movie.

You can thank California Congresswoman Jackie Speier (D-San Francisco/San Mateo) for bringing the issue to light. She had been informed last week by anonymous sources that high levels of cadmium had been detected in the glassware, and she alerted the chair of the U.S. Consumer Product Safety Commission. The commission tested the glasses and confirmed they contained cadmium.

All four designs—Puss ’n’ Boots, Shrek, Princess Fiona and Donkey—are affected by the recall. Refunds will be available beginning Tuesday. Consumers with questions may also call McDonald’s at (800) 244-6227.

“Although McDonald’s did the right thing by recalling these products, we need stronger testing standards to ensure that all children’s products are proven safe before they hit the shelves,”  Speier says. “Cadmium is a toxic substance that is extremely dangerous to the developmental health of children.”

Photos (top to bottom): Consumer Product Safety Commission, McDonald’s