Four import companies have voluntarily recalled 150 million pieces of toy jewelry sold in vending machines because some of it could pose a risk of lead poisoning, federal regulators said yesterday.

The recall, announced by the Consumer Product Safety Commission, is one of the largest in U.S. history. It involves various styles of rings, necklaces and bracelets.

About half of the 150 million pieces of toy jewelry contain lead, but because it is difficult to distinguish the lead jewelry from the non-lead jewelry, the industry decided to recall all of it, the commission said.

The four companies involved are A & A Global Industries Inc. of Cockeysville, Md.; Brand Imports LLC of Scottsdale, Ariz.; Cardinal Distributing Co. of Baltimore; and L.M. Becker & Co. of Kimberly, Wis.

The commission said it has received one report of lead poisoning in which a child swallowed a piece of toy jewelry that had been previously recalled. No reports of injury or illness have been received for the recalled products announced yesterday, the commission said.

Young children sometimes chew or swallow items like these, and lead can leach from the jewelry into the child's body. Lead poisoning in children is associated with behavioral problems, learning disabilities, hearing problems and growth retardation.

The four firms told the commission that they stopped importing toy jewelry with lead and will work on eliminating hazardous levels of lead in future imports of toy jewelry.

Commission Chairman Hal Stratton urged parents to search their children's toys for this jewelry and to throw away the recalled items.

The commission analyzed some samples of toy metal jewelry sold in vending machines and found 10 products with lead. The industry volunteered to recall additional products.

The rings are gold or silver in color with different designs, paint finishes and center stones.

The necklaces have black cords, black ropes or gold or silver chains. They have pendants, crosses or various geometric designs and may include fake gemstones.

The bracelets include charm bracelets, bracelets with medallion links and bracelets with fake stones.

All the jewelry was manufactured in India.

The toy jewelry was sold in vending machines nationwide from January 2002 through June 2004. The items cost between 25 cents and 75 cents.

Consumers should throw away the recalled jewelry. People seeking more information can contact an industry hotline at 800-441-4234 or visit the firms' Web sites.