呼気CS<SUB>2</SUB>濃度の労働衛生学的意義について : 許容濃度設定のための考察

Abstract

From the environmental and medical records obtained by factory surveys in five staple fiber and artificial silk plants, average CS2 concentration in the spinning room, expired CS2 concentration of the workers during and after the day shifts, urine CS2 level in the following morning before entering the work, and clinical signs including subjective complaint and results of laboratory tests were summarized to evaluate the occupational exposure to CS2 with a view to industrial hygiene control.1, CS2 level of the expired air was gradually elevated during the shift and reached equillibrium to the environmental CS2 in about 3 hours. At the excreting stadium the expired CS2 level fell sharply in the first 20 minutes and continued tracing an exponential or parabolic curve. The form and the level of this curve was varied by the individual difference in accordance with the serum cholesterol level. An animal experiment revealed in this connection, that the coefficient o〓foo istribution of environmental vs. blood CS2 concentrations rose when the serum cholesterol level was elevated after four month exposure to CS2. 2. Threshold limit of the average CS2 concentration in the working place was estimated to be 15 ppm on 8 hour basis, when the free CS2 concentration in the morning urine before entering the shift showed a threshold level and expired CS2 concentration immediate after the shift was about 2 μg/dl. When values exceeds this level, various clinical signs and complaints as shown in Figure 4 began to be observed in several workers. As the indices of industrial exposure to CS2 values obtained by analyses of expired CS2 at the end of the shift and urine at the beginning of the following shift are extremely useful for evaluating the industrial hygiene practice and control in the viscose rayon industry.