Two cases of aplastic anemia among over-glaze decoration workers and their working conditions in potteries (author's transl)

Abstract

1) Two cases of aplastic anemia were found among over-glaze decoration workers in potteries. They had used solvents containing benzene for treating liquid gold (a kind of pigment) or for wiping off the varnish (an adhesive for printing transfer papers). So, the relationship between aplastic anemia of the two cases and their benzene exposure were investigated. Case 1: a 49 year-old man who had been exposed to benzene occasionally for one or two months in 1967 and four hours a day for five months from October, 1971 to February, 1972. He had been in good health before he began to complain of headache in March, 1972. His health conditions acutely worsened and he was admitted to a hospital with a diagnosis of aplastic anemia on March 13, 1972 (Table 1). His severe anemia remitted six months after admission (Fig. 1). The solvent used by him contained 90% of benzene and 10% of toluene. He had used 50 to 100 ml of the solvent a day. It was estimated from the working conditions investigated in the similar factories that he might have been exposed to benzene continuously at about 0.5 ppm and intermittently even at 7.5 to 30 ppm or more. Case 2: a 60 year-old woman who had been exposed to benzene nine hours a day from 1952 to the spring of 1967. She had often complained of nausea, vomiting, fever and pollakisuria since the summer of 1968, and she was admitted to a hospital in March, 1969. She was diagnosed as aplastic anemia at that time (Table 2). She died three months after her admission in spite of medical treatment (Fig. 2). The autopsy revealed that her bone marrow was hypoplastic. She had daily used about 125 ml of the solvent containing benzene. It was estimated from the working conditions investigated in the similar factories that she might have been exposed to 7.5 to 30 ppm or more of benzene almost continuously throughout her working time. Judging from the relationship of the clinical course and the benzene exposure in the two cases, and from the results of other reports on the benzene poisoning (Table 5), it could be considered that aplastic anemia in both cases was caused by benzene. 2) The working conditions, especially benzene exposure, were investigated in six over-glaze decoration factories. Factories A and B were investigated in March, 1977, and factories C, D, E and F in July, 1977. It was revealed that benzene had been used in all the factories (Table 3), which were poorly ventilated. Above 150 ppm of benzene were detected close to the respiratory zone of a worker in factory B (Table 4, Fig. 5). Benzene above 25 ppm (the ceiling value of MAC recommended by the Japan Association of Industrial Health) were often detected in other factories too (Fig. 4). Total phenol in the urine were colorimetrically determined after the indophenol reaction with Gibbs' reagent in 16 workers usually exposed to benzene, six workers occasionally entering into the workrooms where benzene was used and eight students as the control (Fig. 6). Concentrations of total phenol in the urine of the usually exposed workers had a tendency to be higher in the evening (after work) than in the morning (before work). The concentrations of total phenol in the morning urine of the usually exposed workers were significantly higher than those of the students and had a tendency to be higher than those of the occasionally exposed workers. The concentrations of total phenol in the evening urine of the usually exposed workers were significantly higher than those of the occasionally exposed workers. These results showed that benzene had been actually inhaled by the workers. 3) It was made clear that benzene had been used up to very recent time in over-glaze decoration factories and that the ventilation of the factories were not satisfactory. Benzene is rarely used as a solvent in industries in Japan because it has strictly been restricted by law to use it as a solvent. But benzene had been used exceptionally until recently in over-glaze decoration factories, becaus