WASHINGTON — Questions are being raised about Medicare in the meningitis outbreak that has rekindled doubts about the safety of the nation's drug supply.

The health insurance program for seniors long ago flagged compounded drugs manufactured without Food and Drug Administration oversight as safety risks. The outbreak that has sickened more than 250 people nationally has been linked to an injectable steroid from a Massachusetts compounding pharmacy.

In 2007, Medicare revoked coverage of compounded inhaler drugs for lung disease, citing safety reasons.

But Medicare doesn't seem to have consistently used its power to deny payment, and critics say that enables the compounding industry to flourish.

Sen. Charles Grassley says Medicare has some explaining to do. The Iowa Republican says every avenue for preventing another crisis must be explored.