According to the regulation of the Pneumoconiosis Act (1960), roentgenological classification of the type of pneumoconiosis, Maximum Breathing Capacity, and Exercise Index were studied in 824 workers exposed to dust and 222 healthy adults. There were not so significant correlations between X-ray findings and pulmonary function disterbances. Most of PR₁ and PR₂ showed normal or slight disorder in functional tests. As to % MBC, PR₁ and PR₂ showed normal while PR₃ was mostly under 90%. As to Exercise Index, PR₂ was above 25%. Comparison of alveolar gas exchange during the step-up exercise tests were made among three groups (69 cases in total), i.e. silicosis (48 cases), tuberculosis (11 cases) and healthy adults (11 men). In these cases, exercise ventilation (ventilation during the third minute of exercise), oxygen uptake, oxygen removal, presence of oxygen debt at the fifth minute after exercise, rate of arterial blood oxygen saturation, carbondioxide tension of arterial blood, and intrapulmonary distribution of inspired gas were measured. 48 cases of silicosis were classified in four groups and the progress of the disease was discussed. First Group … Emphysematous changes advanced, alveolar hypoventilation and uneveness of intrapulmonary distribution of gas appeared. Exercise Index showed normal value while % MBC decreased. This group was often under estimated in the screening test practice as prescribed by the Pneumoconiosis Act. Second Group … Fibrotic changes advanced, disturbance of oxygen uptake was greater than ventilatory disturbance. Rate of oxygen saturation in arterial blood decreased. In this group, % MBC decreased and Exercise Index increased. Third Group … Insufficiency of gas exchanges were compensated by hyperventilaton. This group was divided in two subgroups, adequately compensated (sub-A) and inadequately compensated (sub-B). Both sub-groups showed normal level of oxygen saturation during exercise but oxygen debt exsisted in sub-A and not in sub-B. In sub-B group, Exercise Index showed relatively high value while % MBC was normal. This group was often overestimated in the practice of the screening tests. Fourth Group … Normal gas exchange level was maintained.

View full abstract

Three hundred and seventy four industrial enterprises listed in the Department of Labor as handling ionizing radiations were investigated by means of questionnaires. Answers were received from 229 radiation handling works, involving 1, 742 workers. Number of sources were 824, among which x-ray equipments for nondestructive inspection was ranking at the top and radioactive substances, industrial gamma ray apparata, x-ray diffraction apparata, accelerators, nuclear reactors were following in the given order. According to industrial classification, the order was transportation machine makers (mainly shipbuilding), electric equipment makers, chemical industry, steel and nonsteel metal industry. Characterisitics could be admitted to their radiation sources by the sorts of enterprises. Exposure doses were investigated in those participating in one kind of radiation sources. Calculating for a year, the doses were:below (and including) 10 mrem 53.5%, under 500 mrem 33.9%, under 1000 mrem 8.3%, under 5000 mrem 3.9% and above 5000 mrem 0.4%. The measurement was taken by way of film badge method. It seldom exceeded the exposure doses given by the recommendation of ICRP. Pocket dosimeter showed almost the same, only having a tendency to show a slightly higher amount of dose compared with film badge method. Exposure dose took the order of industrial x-ray, industrial gamma ray, medical x-ray and medical gamma ray. In the scale of enterprises, there was a tendency that the exposure dose was larger in small industries.

View full abstract