WHAT: The California Department of Health Care Services mailed letters to 49,352 Medi-Cal beneficiaries Feb. 1 with each patient’s Social Security number printed on the address label. The agency didn’t find out about the security mishap until Thursday, and began dropping warning letters into the mail Saturday. So far, it has cost the state $50,000.

WHO: Elderly, disabled or chronically ill Californians receiving adult day care services from the state had their Social Security numbers exposed. The follow-up warning advised them to place a fraud alert with the three credit reporting agencies.

WHAT’S BEING DONE: The Health Care Services Department is investigating, and it promised to “redouble our efforts ... to prevent such errors from occurring in the future.”