Workers in toxicology suits visited the Food Safety and Toxicology Building Wednesday to investigate an unknown irritant that sent a 38-year-old university employee to Lansing's Sparrow Hospital. She was later released.

Officials with the East Lansing Fire Department, MSU police and the Office of Radiation, Chemical and Biological Safety investigated for several hours after receiving a call just after 11 a.m.

A female MSU employee opened the door of a basement walk-in freezer and said her eyes became irritated, MSU police Lt. Scott Beckner said.

Police have ruled out a Freon spill or anything involving chemicals, MSU police Sgt. Florene McGlothian-Taylor said.

A basement corridor was closed for several hours and five employees were evacuated.