PubMed1982
We previously reported that the working and health conditions of vibrating tool operators in an iron foundry were investigated in 1975 and vibration hazards were observed to occur frequently in workers operating chipping-hammers powered by compressed air. After that, we instituted medical treatment for the afflicted workers and improvement of working conditions in the foundry, and have performed annual medical examinations for four years. In this paper, the course of hygienic control and the change in the medical findings of twenty-four chipping-hammer operators are reported. 1. The following measures were taken to improve the working conditions of chipping-hammer operators and therapy for patients (Table 1): (1) The operating time of vibrating tools, including chipping-hammer, was limited to two hours per day. The casting process was improved to diminish the flashes that are the objects of chipping-hammer operation. For the purpose of reducing the vibration transmitted to the operator, a servo-arm that has a servomechanism for the chipping-hammer was developed and introduced. (2) Infrared lamps in the foundry and air curtains at the doorway were installed for keeping the chipping-hammer operating area warm. A warm room was set up in the foundry for providing warmth during rest periods and protective clothing against the cold was provided. (3) Workers who displayed health disturbances by medical examinations were treated during the cold season from November to April by periodic visits to the clinic or extended hospitalization, or transferred to job without vibration exposure, according to their stage of disease. Preventive treatment with vasodilator and bubble bath was performed in winter for the chipping-hammer operators. 2. In order to estimate the effect of these countermeasures, annual medical examinations were conducted in March 1975, March 1976, April 1977 and March 1978. Such subjective symptoms as Raynaud's phenomenon, finger numbness, finger listlessness, heavy-headedness, forgetfulness, irritability and hearing disorder showed a tendency for improvement, but other complaints did not (Tables 2-4). The improvement of Raynaud's phenomenon is considered to be due not merely to the countermeasures but also to reducing the chance of provocation and therefore the countermeasures should not be overestimated as a factor of recovery of vibration hazards. Of the functional tests, a tendency for improvement was recognized in sensory functions and peripheral circulatory functions, but not in motor functions (Tables 5, 6). However, the course of recovery was not fast and some advanced cases, especially those using chipping-hammers for more than ten years, showed less improvement after hospital treatment (Table 7, Fig. 1). This indicates the importance of hygienic control which enables vibration hazards patients to have early diagnosis and treatment. Furthermore, in order to eradicate the vibration hazards in the cast metal industry, a drastic reform of the finishing process is considered to be necessary.