オートバイ乗務により発生した郵便労働者の振動障害

抄録

In Japan, in the last several years, mail matters increased so remarkably that motorcycles came to be used for their speedy and efficient delivery and gathering. Moreover, enlargement and speedup of motorcycles proceeded. So much so that, many mailmen have come to us complaining of numbness or waxy white attack of their hands fingers. Frequent outbreaks of these complaints of mailmen were suspected to be caused by motorcycle riding. The authors made the present study in order to make clear the mailmen's vibration hazards induced by motorcycle riding. Since 1977, the authors have made the studies on the following three items in their respective ways. (1) Investigations on the subjective complaints The authors obtained informations through questionnaires from about 2, 700 outdoor labourers of post offices in Shizuoka Prefecture, concerning subjective complaints and labour conditions. The withdrawal was about 95.9%, and collected answers were analyzed. Subjective complaints in the group using only motorcycles and the group using both motorcycles and bicycles were generally much more in the percentage than those in the group using only bicycles (Table 2). (2) Objective examinations on the health status Physical examinations of the peripheral blood circulatory system and the peripheral nervous system were made on 120 outdoor workers of post offices in S. and N. Prefectures. Of these, 100 were motorcycle riders, and 20 bicycle riders. These 100 motorcycle riders were divided into 3 groups (Table 5). Measured items were temperature of the finger skin, nail press test, vibratory sense threshold, and pain sense threshold. The difference in the values of peripheral circulatory and nervous systems by cooling between the groups using motorcycles, especially the group with waxy white fingers, and the group using only bicycles was often found statistically significant (Table 7). (3) Time studies on the outdoor working hours By pursuing four mailmen riding motorcycles from the beginning to the end of outdoor working, their riding hours a day for mail delivery and gathering were analyzed, in order to make clear their vibration exposure time. It was found that the vibration exposure time per day for the mailmen by motorcycle riding were over two hours (Table 8). It has been reported that the maximum vibration acceleration level exceeds the exposure guidelines of ISO, at the handle-bars of a motorcycles running on the paved road. Then, from the results above described, it is surmised that the mailmen's vibration hazards induced by motorcycle riding are widely occurring in our country.