An Epidemiological Study of Accidential Injury in Working Field

Abstract

Epidemiological analysis of accidents in the working field, with a particular emphasis on the frequency distribution of accidents, was carried out on the accidential injuries that had occurred among the workers of the industrial enterprises under the jurisdiction of Kagoshima Lobor Standard Office during the 1-year period January to December 1980. The followings were the main findings of this study. 1) When the kind of occupation and the size of workers were arranged, the distribution for the frequency of accidential injuries per an enterprise conformed to the negative binomial distribution rather than to the Poisson series, suggesting that every enterprise was not equally exposed to the risk of accidents. The enterprises having small number of workers appeared to have lower accident risk as compared with those having large number of workers for all the enterprises involved but the reverse was true with respect to the accident rate for the enterprises at the risk which were associated with accidents. 2) The distribution for the frequency of industrial accidents per a worker conformed to the negative binomial distribution for all the workers of all enterprises but to the Poisson series for the workers of the enterprises at which the accidents occurred. Assuming that the frequency of industrial accidents per a worker for those who had at least one accident is a truncated Poisson distribution, the number of workers at the risk of accidents was estimated by trial and error. 3) The distribution for the frequency of accidents per a day conformed approximately to the negative binomial distribution rather than to the Poisson series, indicating that the days having high accident risk tend to cluster. The frequency of accidents was highest on Monday followed by Tuesday and the lowest being on Sunday. 4) The internal stractures of accidents were compared among the different occupational groups of enterprises. These stractures involved sex, age class, experience, time of injury, nature of injury, type of acident, causative agent, part of body injured and the duration of absence from work.