WASHINGTON (AP) — Government health experts said Thursday there are few reasons to continue using metal-on-metal hip implants, amid growing evidence that the devices can break down early and expose patients to dangerous metallic particles.

The Food and Drug Administration asked its 18-member panel to recommend guidelines for monitoring more than a half-million U.S. patients with metal hip replacements. The devices were originally marketed as a longer-lasting alternative to older ceramic and plastic models. But recent data from the U.K. and other foreign countries suggests they are more likely to deteriorate, exposing patients to higher levels of cobalt, chromium and other metals.