Surveillance of hazardous materials events in 17 states, 1993-2001: a report from the Hazardous Substances Emergency Events Surveillance (HSEES) system.

BACKGROUND: Thousands of acute hazardous materials (HazMat) releases occur annually throughout the United States. To prevent human exposure and resulting injuries, it is critical to understand the frequency with which these releases occur, the locations involved, the industries associated, and the specific substances being released.

METHODS: HazMat events data from the Agency for Toxic Substances and Disease Registry's Hazardous Substances Emergency Events Surveillance (HSEES) system were analyzed for frequency and locations of occurrence, major industry categories and sub-categories involved, and substances released. The data analyzed were collected from 17 participating state health departments for 1993 through 2001.

RESULTS: During 1993 through 2001, 53,142 HazMat events occurred. Of the 17 states analyzed, Texas had the most releases, comprising 38.3% of all HSEES events. Of the 14 major US Census industry categories analyzed, the manufacturing category had the highest percentage of events (48.7%) followed by transportation, communication, and other public utilities (27.5%). Of the 10 states that participated during the entire analysis period, the numbers of events increased 64.3%. Twelve of 14 major industrial categories experienced increases in numbers of events over the analysis period, while public administration and active duty military events decreased. The substances released most frequently overall included ammonia, sulfur dioxide, and sulfuric acid, respectively.

CONCLUSIONS: The HSEES data appear to reflect an upward trend in the occurrence of hazardous HazMat events. While it is difficult to definitively conclude whether this trend is due to more events actually occurring or from other factors, reviewing historical HazMat data may help communities, government agencies, and industries prevent or better prepare for potential events in the future.