An outbreak of xylene intoxication in a hospital

On January 3, 1980 an outbreak of illness occurred in 15 employees of a small community hospital. Symptoms included headache, nausea, vomiting, and dizziness or vertigo; the duration of illness ranged from 2 to 48 hours. The employees who became ill all worked in areas of the hospital served by one central ventilation system. None of the 180 persons working in other parts of the hospital developed symptoms requiring medical care. Less than 1 hour before the outbreak occurred, 1 liter of liquid xylene had been discarded down a sink drain in the pathology laboratory. Simulation experiments confirmed that xylene vapor could have been drawn into the room that contained the fan unit of the ventilation system. This outbreak illustrates an unusual route of exposure to a widely used laboratory chemical.