Cancer incidence was studied among 6,144 male foundry workers who were invited to participate in either of two Danish national silicosis surveys conducted during 1967-1969 and 1972-1974. Cancer incidence was followed through to the end of 1985 by computerized linkage to the Danish Cancer Registry, and Standardized Morbidity Ratios (SMRs) were calculated based on incidence rates for the Danish population. For the entire cohort, significantly elevated SMRs were seen for all cancers (SMR, 1.09; 95% CI, 1.01-1.18) and lung cancer (SMR, 1.30; 95% CI, 1.12-1.51), and SMRs were at the borderline of statistical significance for bladder cancer (SMR, 1.24; 95% CI, 0.97-1.59). Excess lung and bladder cancer risk were confined to workers who had worked in foundries for at least 20 y. There was a positive correlation between silicosis prevalence in employees at the foundries at the time of the x-ray examinations and lung cancer incidence during the follow-up period. Squamous cell carcinomas, anaplastic carcinomas, and other lung cancers accounted for the excess lung cancer risk, whereas there was not excess risk among the foundry workers for adenocarcinomas of the lung.
Data from nationwide registry-based cohorts of patients hospitalized for silicosis in Sweden from 1965 to 1983 and Denmark from 1977 to 1989 were linked to national cancer registries in both countries and to mortality data in Sweden to evaluate the risk of cancer and other disorders among hospitalized silicotic patients. The overall cancer standardized incidence ratio (SIR) was 1.5 (95% confidence interval [CI], 1.3 to 1.7) in Sweden and 1.7 (95% CI, 1.2 to 2.3) in Denmark, primarily because of elevations in primary lung cancer in both Sweden (SIR, 3.1; CI, 2.1 to 4.2) and Denmark (SIR, 2.9; CI, 1.5 to 5.2). For Sweden, the all-causes standardized mortality ratio (SMR) was 2.0 (1.9 to 2.2). The SMR for all malignancies was 1.5 (1.2 to 1.7), primarily because of excesses of lung cancer (SMR, 2.9; CI, 2.1 to 3.9). The significant increase in mortality for all infectious and parasitic conditions (SMR, 11.2) was primarily due to tuberculosis (SMR, 21.8). Significant excesses in mortality from silicosis (SMR, 523), bronchitis (SMR, 2.6) and emphysema (SMR, 6.7) contributed to the elevation in nonmalignant respiratory deaths (SMR, 8.8), whereas excess mortality from musculoskeletal disorders (SMR, 5.9) was due to six deaths from autoimmune diseases. Despite limitations of the available data, our findings are consistent with previous reports indicating that silicotic patients are at elevated risk of lung cancer, nonmalignant respiratory diseases, tuberculosis, and certain autoimmune disorders.
To reduce the incidence of occupational diseases related to exposure to respirable silica at work, the main industries in the EU associated with respirable silica agreed on measures to improve working conditions through the application of good practices. These practices were included in “The Agreement on Workers Health Protection through the Good Handling and Use of Crystalline Silica and Products Containing it” (NEPSI agreement), signed in April 2006. In Finland, we have previously seen a decline in exposure to respirable quartz in relevant industries upon the treaty coming into effect, during the years 2006?2013. The present paper examines trends in exposure to respirable crystalline silica in Finland from 2006 to the end of 2017. In addition, we looked at changes in the number of exposed workers and the prevalence of silicosis and lung cancer associated with the exposure during the same period. The aim was to find out whether the decline in exposure previously recorded had continued, and whether this, in addition to the previously reported descent in exposure, was reflected in the amount and prevalence of occupational diseases associated with inhaling respirable quartz. In the present study, during the period 2013 to 2017 no further improvements were observed. The exposure remained at an average level of 20?50% of the current OEL8h. This is not necessarily sufficient to eliminate silicosis, lung cancer or other health effects associated with exposure to respirable silica in affected workplaces. To bring about further improvements in exposure, we suggest the present OEL8h in Finland (0.05 mg/m³) and particularly in the many EU countries with an OEL8h of 0.1 mg/m³ be lowered to 0.020?0.025 mg/m³. Secondly, branches outside of the NEPSI treaty where the number of exposed workers is increasing in Finland and possibly in some other EU countries as well, namely building and refinery industries, would be advised to sign the treaty. In addition, as a result of signing, good practices should be developed for work tasks where exposure to respirable silica is of concern in these industries.
The frequencies of HLA antigens in 27 patients with silicosis were compared with those of referents matched for exposure to silica dust, age, and sex, and having no roentgenographic signs of silicosis. A group of 900 blood donors served as an additional reference group. The prevalence of HLA-Aw19 was higher in the silicosis patients (29.6 percent) than in the silica-exposed referents (3.7 percent; p = 0.02). In turn, the frequency of Aw19 in the unexposed population consisting of blood donors (19.6 percent) was higher than that of silica-exposed referents (p = 0.04). Accepting that the prevalences of HLA antigens in the blood donors fairly well describe those of the silica-exposed population, the highest risk of developing advanced fibrosis was associated with the phenotypic combination Aw19,B18 (observed-expected ratio = 17.05; p less than 0.01). The results suggest that HLA-Aw19 and the haplotype Aw19,B18 are, at least in Finnish population, associated with a progression into advanced silicotic fibrosis.
The incidence of lung cancer among 280 silicotic men working in the ceramics industry and notified to the Swedish Silicosis Registry has been investigated. During the study period 1958-83, the risk of lung cancer (nine cases) was double that expected based on national rates. There was no increased incidence of cancer at any other site. The results are in agreement with those of both animal and epidemiological studies of quartz exposure and point to an increased risk of lung cancer, especially among silicotics. Various possible explanations of this increased risk are discussed, but further studies are required.