Releases from improper chemical mixing, Hazardous Substances Emergency Events Surveillance system, 1996-2001.

Objective: To examine the public health consequences of acute hazardous substance releases resulting from the improper mixing of chemicals.

Methods: Data from the Agency for Toxic Substances and Disease Registry's Hazardous Substances Emergency Events Surveillance system for 1996-2001 events were analyzed.

Results: "Private households" was the most frequent industry classification among improper mixing events, and chlorine was associated with a greater prevalence of improper mixing events. Releases from improper mixing were considerably more likely to involve fire, explosion, and fire-explosion combined; were markedly more likely to result in personal injury (48% for improper mixing events vs. 7% other events); and had a significantly greater percentage of victims with traumatic injury (PR = 3.07, 95% CI = 2.55-3.71).

Conclusions: Improper chemical mixing can cause dangerous, harmful reactions and are preventable. Consumers should be educated to avoid mixing noncompatible products.