RELIABILITY OF ACCIDENT CASE-HISTORIES CONCERNING HAZARDOUS CHEMICALS - AN ANALYSIS OF UNCERTAINTY AND QUALITY ASPECTS

A recent analysis of accident case histories achieved from readily available accident lists, has exposed the fact that an accident may be described more than once in the literature. Important discrepancies were found between the various main (accepted) sources in the field of risk analysis and loss prevention. An analysis of the differences found, and an assessment of the quality of accident case histories is attempted. Initially the analysis is limited to the number of fatalities, because this information is easy to measure, often available and leads itself to easy statistical treatment. The number of fatalities can thus be used as an indicator for the variability of the information found in accident case history reporting. The analysis is based on 595 transportation accidents involving hazardous chemicals from road, rail and pipeline transportation modes. Thirty-nine of these accidents were found to have three characteristics in common: (1) they happened before 1980, (2) they resulted in fatalities, and (3) they were described by more than one source. These 39 accidents are used in the analysis of the reliability of the number of fatalities reported in case histories. Sixteen accidents (or 41%) show discrepancies (in terms of fatalities) between the sources. Extrapolating the results of the "fatality" analysis to the other parameters, and supported by an analysis of selected cases, the general quality of information from accident case histories is evaluated. The result is a useful tool for assessing the quality of the various types of information. Using the terms "low", "medium" and "high" to describe the quality, a table can be compiled. This tool shows that the information on date and place of the accident is of high quality, the event description and the number of casualties are of medium quality, and the information about chemical name and amount is of low quality.