Abstract: At approximately 8:30 a.m. on March 31, 1997, Employee #1 was cleaning a lab hood, a regular duty in the Pharmacology Department at the University of California, San Diego. He was wearing short latex gloves, safety glasses, and a short-sleeved shirt. Employee #1 picked up a bottle of inorganic arsenic from the back of the hood. The top popped off and he dropped the bottle, spilling arsenic trichloride on his left arm; one drop landed on his lower arm and two drops landed on his upper arm. Employee #1 washed his arm with water, then neutralized the material that had spilled outside the hood. Approximately 1 hour later, he went to an emergency room where he was treated and released. Employee #1 did not suffer any long-term effects from the exposure. The accident might have been prevented by the use of proper PPE. Better housekeeping in the hood might have alerted him to problems with the container, since the presence of white powder around the rim of the cap indicated that the material had become contaminated by water vapor and pressure was building up inside. The accident occurred at a chemical research lab with an appropriately tested and operated lab hood that contained all operations involving arsenic trichloride. There were no witnesses to the accident.