Aviation officials say a passenger doing her nails was the source of a mysterious odor that forced a flight from Chicago to San Diego to be diverted to Denver Saturday.

United Flight 787 was forced to land at Denver International Airport after the flight crew detected an unknown odor.

Federal Aviation Administration spokesman Allen Kenitzer says the pilot noticed that his cargo included several five-liter containers of acetone, a hazardous substance.

A check found none of the containers leaking.

Authorities later determined the odor came from a passenger who was doing her nails on the flight.

It's unknown if she was using nail polish or remover — both contain acetone.

Kenitzer says nail polish is allowed aboard commercial flights.