Abstract
Chain saws have been widely used in Japan, but Raynaud's disease of occupational origin (white wax disease) occured among forestry workers since about 1956.
Main signs of the disabilities resulting from the use of vibrating tools are (1) blanching of fingers (2) numbness of fingers, (3) joint and muscle pains. Among these blanching of fingers (Raynaud's disease) has been considered most serious.
Experimental studies were carried out for the purpose of investigating the effect of mechanical vibration on the blood flow in the digit by using a mechanical plethysmography in three seasons of summer, autumn and winter
Blood flow in the digit was more closely correlated with enviromental conditions than vibratory load. Hanting reaction was highest in autumn. In case of low temperature, the blood flow in the digit was reduced in the following experiments. When such highstringing of vasomotor nerve in sepeated several times, it seems to cause some trouble.
