Malathion-induced epidemic hysteria in an elementary school.

More than 100 people, including firefighters, police officers, paramedics, nurses and physicians responded to reports that students at an elementary school had been exposed to an unknown and possibly toxic substance; 296 students were transported to eight hospital emergency departments. None were diagnosed as acutely ill. The substance was subsequently identified as approximately 22 ml of malathion, diluted in 15 L of water and applied by means of a hand-held sprayer approximately 100 m from the school. The odor apparently drifted to the school in 19 to 24 km/h winds. The episode was determined to be epidemic hysteria, possibly triggered by the malathion odor, but perpetuated by the stress of the emergency response. Hallmarks of epidemic hysteria are discussed, and recommendations for dealing with similar events are offered.