McDonald's on Friday recalled more than 13 million drinking glasses sold in North America to promote the latest "Shrek" movie because they contain a toxic metal.

"The designs on the glasses contain cadmium. Long-term exposure to cadmium can cause adverse health effects," said the US Consumer Product Safety Commission, an independent government agency.

"McDonald's is asking consumers to immediately stop using the glass out of an abundance of caution," it said of the US-manufactured "Shrek Forever After 3D" collectible drinking glasses.

The glasses were sold only in the United States and Canada, the company said, recalling 12 million in the US and 1.4 million in Canada.

They were sold exclusively at McDonald's restaurants in the US beginning in May for about two dollars each as part of a campaign to promote "Shrek Forever After," produced by DreamWorks Animation and released by Viacom's Paramount Pictures.

McDonald's said the glassware was evaluated by an independent third-party laboratory accredited by the commission, "and determined to be in compliance with all applicable federal and state requirements at the time of manufacture and distribution."

"However, in light of the CPSC's evolving assessment of standards for cadmium in consumer products, McDonald's determined in an abundance of caution that a voluntary recall of the Shrek Forever After glasses is appropriate," the fast-food giant said in a statement.

The company said its safety standards were among the highest in the industry and that it had a strong track record.

"When the US Consumer Product Safety Commission approached McDonald's about cadmium in their current movie-themed drinking glasses, the company responded quickly, agreed to cooperate fully and acted on the side of caution," said CPSC spokesman Scott Wolfson, according to the statement.

"The glasses have far less cadmium than the children's metal jewelry that CPSC has previously recalled," he said.

McDonald's shares closed 1.69 percent lower at 66.70 dollars in New York.

According to the World Health Organization, cadmium is classified as a human carcinogen and exerts toxic effects on the kidney and the skeletal and the respiratory systems.

Cadmium is generally present in the environment at low levels, but human activity has greatly increased those levels, according to WHO.