Federal regulators are expanding their investigation into children's jewelry that contains the toxic metal cadmium, promising that a recall announced Monday of "Best Friends" charm bracelets will not be the last.

"More recalls are in the works," U.S. Consumer Product Safety Commission spokesman Scott Wolfson said.

Those recalls would be the result of voluntary testing by companies, some of which have found troubling levels of cadmium and then reported those results to the agency, Wolfson said. He would not say how many products are under scrutiny.

In addition, in recent weeks agency inspectors working at 10 of the nation's largest ports have screened imports of jewelry for cadmium. In one instance, a shipment of Chinese jewelry was turned away.

Word of expanded federal efforts came as the consumer safety agency announced the voluntary recall of about 19,000 "Best Friends" charm bracelet sets made in China and sold exclusively at the jewelry and accessories store Claire's, which has more than 3,000 outlets in North America and Europe.

"Cadmium is toxic if ingested by children and can cause adverse health effects," the agency said in its recall announcement. Medical research shows that cadmium in high levels is a known carcinogen and can harm kidneys and bones.

Agency scientists confirmed independent test results that were first reported in an Associated Press investigation in January, which showed high levels of cadmium in the "Best Friends" bracelet.

The recall pertains only to items previously sold at Claire's; several days after AP's initial investigation became public, the chain said it would immediately stop selling them.

While the CPSC did not release its results, testing done for the AP revealed that bracelets sold at Claire's contained up to 91 percent cadmium by weight, and shed alarming amounts during a test that examined how much cadmium children might be exposed to if they accidentally swallow one of the charms.

Consumers should take the bracelets away from children and return them to Claire's for a replacement or refund, according to the announcement. The bracelets sold for about $12.

The CPSC identified the manufacturer as Dae Yeon Industries Corp., of China. Claire's said Monday that it has stopped further shipments from the company.

The recall was the third prompted by AP's reporting. Before this year, no consumer product in the United States had been recalled because of cadmium.

"Within weeks of these reports, Claire's Stores added procedures requiring all of its suppliers to test for cadmium in children's jewelry," the company said in a statement. "Claire's Stores has taken significant steps to ensure that its products meet or exceed all existing safety standards and has responded swiftly and decisively to address the potential risk of cadmium in children's jewelry."

The reference to existing safety standards reflects the fact that, unlike with lead, federal law sets no specific levels for how much cadmium is permissible in children's jewelry. Federal regulators are operating under generic powers they have to remove hazardous items from commerce, and Claire's urged the agency to set clearer standards.

In the meantime, states from California to Connecticut have started to act.

Last week in Illinois, for instance, the Legislature passed a bill to limit cadmium in children's jewelry that roughly follows a regulatory approach now used for cadmium in toys. That bill is on its way to the governor's desk.

Representatives of jewelry importers and manufacturers have rejected the idea that children's metal jewelry is unsafe.

Michael Gale, executive director of the Fashion Jewelry and Accessories Trade Association, has told several state legislatures that are considering strict limits on cadmium in jewelry that if those laws pass, it might be impossible to put any children's jewelry on stores shelves where those laws apply. In an interview Monday, he endorsed the approach that Illinois took.

At the nation's ports, federal product safety screeners are now using special guns that shoot X-rays into jewelry to estimate how much cadmium each item might contain. Samples of items with high initial results — dozens so far — have been sent to the CPSC's headquarters for detailed lab testing.

In one instance, a shipment of Chinese jewelry shed high levels of cadmium when put through the test that mimics how much would enter the body if accidentally swallowed, agency spokesman Wolfson said. That shipment was then "re-exported" — which under U.S. law doesn't mean it had to be sent back to China.