Silicosis hazards in enamelling; a medical, technical, and experimental study.

Silicosis in enamel workers has been reported by Gaubatz (1940), Bruce (1945), Meures and Graf (1949), and Troisi (1952). One of Bruce's cases had third-stage silicosis (International Labour Office, 1930) and was completely disabled. A search of the literature, however, has revealed no further reports of advanced silicosis in such workers, even after long exposure to enamel dust. The cases described in the literature were attributed to inhalation of silicates, although Bruce discussed the possibility that certain types of enamel could contain free silica. Except for occasional analyses of the quartz content of enamel, dust studies in enamelling processes were not found in the available literature. The exact prevalence of silicosis in Swedish enamel workers is not known, chiefly because medical inspection is not compulsory in that occupation. In a general survey of silicosis in Sweden during the period 1931 to 1953, however, 11 cases accepted by the insurance boards were found in enamelling workers and had had no other known exposure to silica (Ahlmark, Bruce, and Nystrom, 1956, personal communication). The present paper reports the prevalence of silicosis in a Swedish enamelling shop and the investigations performed in order to assess the silicosis risk. The occurrence of silicosis among the employees in a workshop shows that unsatisfactory hygienic conditions have existed. In order to determine the current silicosis hazard dust studies are necessary. As a rule these include estimation of the atmospheric concentration of dust and of its content of quartz, but they are not completely reliable guides to the injurious properties of the dust. Tests on laboratory animals of the fibrogenic potency of the dust may provide a valuable complement to more technical investigations, especially for comparison of different dusts. In the shop we investigated, technical dust studies and animal experiments were therefore performed for appraisal of the silicosis hazard and of the need to introduce further prophylactic measures.