LOS ANGELES — Federal regulators are expanding their investigation into children's jewelry that contains the toxic metal cadmium, promising that a recall announced yesterday 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 19,000 "Best Friends" charm bracelet sets made in China and sold only 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; after AP's initial investigation became public, the chain said it would immediately stop selling them.

Consumers should return the jewelry to Claire's for a replacement or refund, the announcement said.