CANTON, Ohio (AP) -- Talk about leaving a bad tip at the restaurant.

A 22-year-old woman found the severed tip of a thumb in her lunch salad at Red Robin Gourmet Burgers.

Stark County Health Commissioner Bill Franks said a worker at the restaurant, in the Canton suburb Jackson Township about 70 miles south of Cleveland, was chopping lettuce Monday night when he cut off part of his left thumb, including part of the fingernail.

Employees searched for the fingertip, but could not find it. The area was cleaned and sanitized, but the lettuce was placed in a cooler and then used for salads on Tuesday.

"It wound up being served at lunch time Tuesday to a 22-year-old woman," Franks said.

She had eaten most of her salad when she put the fingertip in her mouth, Franks said.

She first thought it was a piece of gristle, a health department report said.

Red Robin spokesman Dwayne Chambers said employees, in their haste to get the injured man to a doctor, failed to follow the chain's procedures and throw out all food in the area.

"We clearly had a breakdown," he said. "We are incredibly sorry about what happened."

Chambers said he spoke with the woman. "She obviously was pretty upset," he said.