Relation of occupations to the regional differences of lung cancer motality in Fukuoka Prefecture

Geographic pattern of lung cancer mortality in Fukuoka Prefecture showed elevated mortalities among males in the Chikuho district where many coal-mines had long been operated as one of the biggest coal-mining areas in Japan. The analysis in relations of occupations to lung cancer mortality revealed that consistently significant correlations exist between lung cancer mortality, and mining and quarrying occupations in every census year after World War II. No other occupations showed consistent relations to lung cancer though a few significant correlations were found only in the recent years. The results appear to suggest that elevated risk of lung cancer among coal-mining workers may exist and deserve further analytical study.     

Silicosis and lung cancer among Chinese granite workers.

Of the 184 cases of silicosis registered between 1 January 1970 and 31 December 1984 in Singapore, all the relevant information was available for 159, which were linked to the population-based National Cancer Register for lung cancer. Nine cases of lung cancer were found. The standardized incidence ratio (SIR) was computed with the age- and calendar-specific incidence of lung cancer rates of Chinese males in Singapore as a basis. Excess risk of lung cancer was found (SIR 2.01, 95% confidence interval 0.92-3.81). Adjustment for smoking showed that it alone could not account for the excess lung cancer risk. There was an increasing, but not significant, trend with increasing severity of silicosis and exposure duration. The results suggest that the severity of silicosis and possibly exposure to free silica may have contributed to the excess of lung cancer among the cases of silicosis studied.     

Non-malignant respiratory diseases and lung cancer among Chinese workers exposed to silica

The objective of this study was to explore whether a medical history for non-malignant respiratory disease contributes to an increased lung cancer risk among workers exposed to silica. We analyzed data from a nested case-control study in 29 dusty workplaces in China. The study population consisted of 316 lung cancer cases and 1356 controls matched to cases by facility type and decade of birth who were alive at the time of diagnosis of the index case and who were identified in a follow-up study of about 68,000 workers. Age at first exposure and cigarette smoking were accounted for in the analysis. Smoking was the main risk factor for both lung cancer and chronic bronchitis. Lung cancer risk showed a modest association with silicosis and with cumulative silica exposure, which did not vary by history of previous pulmonary tuberculosis. Among subjects without a medical history for chronic bronchitis or asthma, lung cancer risk was associated with silicosis (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1 to 2.2), and it was increased in each quartile of cumulative silica exposure. However, risk was not elevated in the highest quartile (OR, 1.3, 1.6, 1.8, 1.4). Among subjects with a medical history for chronic bronchitis or asthma, lung cancer risk was associated with neither silicosis (subjects with chronic bronchitis: OR, 0.6; subjects with asthma: OR, 0.4) nor with silica exposure. In this study population, we observed a modest association of both silicosis and cumulative exposure to silica with lung cancer among subjects who were not previously diagnosed with chronic bronchitis or asthma, but not among subjects who had a medical history for either disease. Risk of lung cancer associated with silicosis or cumulative exposure to silica did not vary by previous medical history of pulmonary tuberculosis.     

Silicosis in dental laboratory technicians--five states, 1994-2000

Silicosis is a debilitating, sometimes fatal, yet preventable occupational lung disease caused by inhaling respirable crystalline silica dust. Although crystalline silica exposure and silicosis have been associated historically with work in mining, quarrying, sandblasting, masonry, founding, and ceramics, certain materials and processes used in dental laboratories also place technicians at risk for silicosis. During 1994--2000, occupational disease surveillance programs in five states identified nine confirmed cases of silicosis among persons who worked in dental laboratories; four persons resided in Michigan, two in New Jersey, and one each in Massachusetts, New York, and Ohio. This report describes three of the cases and underscores the need for employers of dental laboratory technicians to ensure appropriate control of worker exposure to crystalline silica.     

SILICOSIS FROM QUARRYING AND WORKING OF GRANITE

Previous knowledge of silicosis in the Swedish granite industry suggested that the disease was neither common nor severe. In recent years, however, changes in working methods have involved a considerably increased formation of dust, and it was considered likely that the risk of contracting silicosis was increased. Reports from other countries supported this conjecture.

The 34 known cases of silicosis caused by quarrying and working of granite in Sweden were therefore reviewed. The mean duration of exposure to siliceous dust when stage I silicosis was diagnosed was 32 years, and the mean age at diagnosis was 55 years. Despite the relatively long `prediagnosis' exposure to dust, the disease showed a pronounced tendency to progression, and six cases were complicated by pulmonary tuberculosis. Eighty per cent of the men were awarded disablement benefit because of their pulmonary lesions, and four men died from silicosis alone or in combination with tuberculosis.

In Swedish granite works there is room for considerable improvement in dust suppression. Careful checks of such preventive measures and periodic medical examination of exposed persons are strongly advocated.

     

Does occupational exposure to silica cause lung cancer?

Silica is not generally considered to be a carcinogen, however, occupations characterized by high exposure to crystalline silica have excessive rates of lung cancer mortality. Respiratory cancer excesses have been reported from North America and from Europe for the following dusty trades in which exposure to silica is a common factor: iron and steel foundry workers, steel casting workers, sand blasters, metal molders, non-uranium miners, and ceramic workers. These findings have been reinforced by two reports from the Swedish Pneumoconiosis Register and the Ontario Ministry of Labor indicating that silicotics have statistically significant risks of lung cancer mortality. Animal studies suggest that silica can be an initiating carcinogen or can act as a cocarcinogen or promoter when combined with benzo(a)pyrene. We propose three candidate hypotheses and two pathways for silicocarcinogenesis.     

冶金行业矽肺患者肺癌流行病学研究

对全国冶金系统４７个厂矿１９８０年１月１日以前确诊并生存的４３７２例矽肺患者的肺癌进行了回顾性队列研究，观察期从１９８０年１月１日至１９８９年１２月３１日共１０年。研究结果表明：矽肺患者的全死因、全癌（主要为肺癌）、慢支－肺炎－肺心病和肺结核显著超出全国对照组。全癌中以肺癌为主，ＳＭＲｓ为２３７。当将矽肺人群分成包括铁矿、烧结、耐火、冶炼和铸造等不同作业类型后，除铸造（ＳＭＲｓ＝１５７，Ｐ＞０．０１）外所有作业类型的肺癌均显著超出全国对照组（ＳＭＲｓ均在２００以上，Ｐ＜０．０１）。肺癌的这种超出未显示出同矽尘的累计接尘年数和Ｌａｔｅｎｃｙ有相关趋势，且不论是吸烟（ＳＭＲｓ＝２５７，Ｐ＜０．０１）或非吸烟组（ＳＭＲｓ＝２０９，Ｐ＜０．０１）同全国对照组比较均有极显著超出。     

Cancer incidence among foundry workers in Denmark

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.     

铁矿工肺癌病因病例对照研究

本研究系在历史前瞻性队列研究基础上,采用同厂矿队列内病例:对照=1:4配比,对接尘、矽肺、吸烟与肺癌之间关系进行了对比分析。结果未发现肺癌发病与接尘、矽肺有直接关系;但结果说明吸烟与肺癌关系密切。     

Mortality due to silico-tuberculosis and lung cancer among 200 whetstone cutters

The objective of the present study was to examine if the mortality due to tuberculosis and cancer in the lungs was elevated in a cohort of 200 male whetstone cutters. 1955-1995 death certificate-based mortality data on the cohort were available, and the data were reviewed in the present study for mortality due to the two diseases to calculate standardized mortality ratios (SMR) in reference to the health statistics of Kyoto prefecture, where the cohort lived. Among the 200 cohort members, 99 men deceased during the observation period, the deaths including 10 cases of lung tuberculosis (of which 9 cases had silicosis together), 20 cases of all malignancies, and 6 cases of lung cancer (5 cases with silicosis). There was a significant elevation in the mortality due to lung tuberculosis (SMR = 3.47) although SMR for all causes was not elevated (1.10). There was no significant change in SMR for all malignancies (0.78), whereas SMR for lung cancer (1.24) tended to be elevated although insignificantly. Lung tuberculosis was a significant complication of silicosis in 1955-1995. Possible elevation in lung cancer SMR among this cohort needs further studies.     

Chronic obstructive pulmonary disease and occupational exposure to silica

Prolonged exposure to high levels of silica has long been known to cause silicosis This paper evaluates the evidence for an increased risk of chronic obstructive pulmonary disease (COPD) in occupations and industries in which exposure to crystalline silica is the primary exposure, with a focus on the magnitude of risks and levels of exposure causing disabling health effects. The literature suggests consistently elevated risks of developing COPD associated with silica exposure in several occupations, including the construction industry; tunneling; cement industry; brick manufacturing; pottery and ceramic work; silica sand, granite and diatomaceous earth industries; gold mining; and iron and steel founding, with risk estimates being high in some, even after taking into account the effect of confounders like smoking. Average dust levels vary from about 0.5 mg.m3 to over 10 mg.m3 and average silica levels from 0.04 to over 5 mg.m3, often well above occupational standards. Factors influencing the variation from industry to industry in risks associated with exposure to silica-containing dusts include (a) the presence of other minerals in the dust, particularly when associated with clay minerals; (b) the size of the particles and percentage of quartz; (c) the physicochemical characteristics, such as whether the dust is freshly fractured. Longitudinal studies suggest that loss of lung function occurs with exposure to silica dust at concentrations of between 0.1 and 0.2 mg.m3, and that the effect of cumulative silica dust exposure on airflow obstruction is independent of silicosis. Nevertheless, a disabling loss of lung function in the absence of silicosis would not occur until between 30 and 40 years exposure.     

Mortality of a cohort of men in a silicosis register: further evidence of an association with lung cancer

Lung cancer mortality from 1980 to 1986 was studied in a cohort of 1,419 men in a silicosis register who had no previous exposure to asbestos and polyaromatic hydrocarbons. The 28 deaths from lung cancer were statistically in excess of expected (SMR 2.03; 95% CI 1.35-2.93). Excess risks of lung cancer were found in both underground workers (SMR 3.41; 95% CI 1.10-7.97; based on 5 deaths) and surface workers (SMR 1.87, 95% CI 1.18-2.81; based on 23 deaths). All lung cancer deaths were smokers. There was an increase in SMRs with longer latency periods and years of exposure, with the greatest risk found in those who had worked for 30 or more years after more than 30 years since first exposed (SMR 3.07, based on 16 deaths). The risk for lung cancer was higher in those with tuberculosis (SMR 2.52; 95% CI 1.52-3.94) and showed an increasing trend with severity of silicosis, from category 1 to 3 and from category A to C, with highest risk in those with tuberculosis and category 3 (SMR 4.44 based on 3 deaths) or tuberculosis and category C (SMR 7.63 based on 7 deaths). Most of the excess lung cancer risk in silicotics is due to smoking, but a synergistic effect between smoking and silica/silicosis on the risk of lung cancer is also likely. In particular, a possible role of silicosis and tuberculosis as the fibrotic seedbed for malignant growth in the lung is strongly supported.     

Mortality and lung cancer in ceramic workers in the Netherlands: Preliminary results

A retrospective cohort study in 1974 male ceramic workers in the Netherlands was carried out to analyze the lung cancer risk in relation to crystalline silica exposure and silicosis. They had all been employed for two years or longer in ceramic industries between 1972 and 1982. During a health survey, 124 cases of simple pneumoconiosis were diagnosed: after 14 years of follow-up, 161 deaths had occurred. No increased overall and cause-specific mortality was found in the total group of ceramic workers, and a statistically significant cumulative dose-response relation for silica exposure and lung cancer did not emerge. An excess lung cancer mortality appeared among workers with simple pneumoconiosis. The authors conclude that the disease process resulting in silicosis in the ceramic industry carries an increased risk of lung cancer, which is supportive of a nongenotoxic pathway. © 1996 Wiley-Liss, Inc.     

Cancer morbidity in workers at aluminum foundries and secondary aluminum smelters

In a Swedish cohort of workers (n = 6,454) from seven aluminum foundries and three secondary aluminum (scrap) smelters there was no overall excess risk of cancer among male or female workers less than 85 years of age (males: 325 observed cases, standardized incidence ratio (SIR) 1.02, 95% confidence interval (CI) 0.91–1.13; females: 22 cases, SIR = 0.95, 95% CI = 0.60–1.44). In male workers, however, significantly elevated risk estimates were observed for cancer of the lung (51 cases; SIR = 1.49, 95%CI = 1.11–1.96), anorectal cancer (33 cases; SIR 2.13, 95%CI = 1.47–2.99), and sinonasal cancer (4 cases; SIR = 4.70, 95%CI = 1.28–12.01). There was no increase of urinary bladder or liver cancer. Lung cancer risks were highest in workers with a short duration of employment (<5 years) suggesting determinants of risk related to socioeconomic factors rather than the occupational environment under study, but there were also indications of a lung cancer hazard from sand casting of aluminum for 10 years or more (SIR = 2.10, 95%CI = 1.01–3.87). The increase in anorectal cancer could not be etiologically related to occupational determinants of risk. Sand casting of aluminum aside, the cancer risk in secondary aluminum smelting seems to be lower than in primary aluminum smelting and in iron and steel founding, respectively. Am. J. Ind. Med. 32:467–477, 1997. © 1997 Wiley-Liss, Inc.     

Prediction of silicosis and lung cancer in the Australian labor force exposed to silica.

Empirical models for risk, based on recently published epidemiologic data, and simple prediction formulas were used to predict the occurrence of silicosis and lung cancer in the Australian labor force currently exposed to crystalline silica dust. As a result of an 0.9 (range 0.4-1.9)% average lifetime risk, approximately 1010 (range 380-2410) silicosis cases were predicted for the next 40 years among the estimated 136,400 men exposed at current silica dust levels [0.01-0.8 (average 0.094) mg.m-3]. Approximately 630 extra lung cancer cases (95% confidence interval 120-1320) would appear with an average excess risk of 0.5 (interval 0.1-1.1)%, the proportion of silica-induced lung cancer cases being about 15%. Currently 77% of the at-risk labor force is exposed to silica dust levels of < or = 0.1 mg.m-3. With this level as the limit, about 440 (range 140-1210) silicosis cases and 410 (interval 90-780) extra lung cancer cases would occur in 40 years. Adopting this level as the national exposure standard would reduce the risk of silicosis cases by 52% and the excess risk of lung cancer by 36%.     

Occupation and smoking as risk determinants of lung cancer

The standardized incidence ratio (SIR) of lung cancer was determined for different occupational groups in Finland. The data on all cases of lung cancer diagnosed in Finland in age groups of 35-69 years in 1971-1975 were supplemented by information on occupation from the 1970 census (Central Statistical Office). The expected numbers of cases were based on the sex, age and occupation-specific numbers of person-years computed in the Central Statistical Office, and sex- and age-specific incidence rates of lung cancer among the economically active population (as defined 1 January 1971). Compared with the risk of the total economically active population, the relative risk of those not active (SIR) was 1.69 for men and 0.86 for women. Lower than expected relative risks were encountered among highly educated and white-collar male workers (religious, legal, pedagogical, medical, technical and administrative work), in sales work, transport service work and among farmers. High SIRs were found in mining and quarrying, forestry, woodworking (joiners), construction, painting and among unskilled workers. Among women the numbers of cases were small and only one significant SIR was obtained; the risk was lower than expected in farming. Data on the smoking habits of males in different main occupational categories in Finland show that variation between different occupational groups in the prevalence of smoking closely corresponds to that in the SIR for lung cancer (R = 0.96).     

The Occupational Cancer Incidence Surveillance Study (OCISS): risk of lung cancer by usual occupation and industry in the Detroit metropolitan area

This case-referent study assesses occupational risk factors associated with lung cancer, utilizing colon and rectum cancer referents. Complete occupational and tobacco use histories were obtained by telephone interview for 5,935 incident lung cancer cases and 3,956 incident colon and rectum cancer referents. The analysis included 43 usual occupational groups and 48 usual industry groups comprised of at least 10 cases. Among all cases, there were significant elevated risks for excavating and mining workers (OR = 4.01), furnace workers (OR = 3.11), armed services personnel (OR = 3.10), agricultural workers (OR = 2.05), driver sales (OR = 2.21), mechanics (OR = 1.72), painters (OR = 1.96), and drivers (OR = 1.88). Industries with significant elevated lung cancer risk included farming (OR = 2.21), mining (OR = 2.98), and primary ferrous metals manufacturing (OR = 2.43). Analyses of white and black men separately revealed that the excess of lung cancer among mechanics is restricted to black males (OR = 4.16). The risk of lung cancer among armed services personnel is higher among black men (OR = 10.54) than among white men (OR = 3.06). Five of the occupations observed more often among lung cancer cases have probable exposure to diesel exhaust.     

Mortality from lung cancer among Sardinian patients with silicosis

The mortality of 724 subjects with silicosis, first diagnosed in 1964-70 in the Sardinia region of Italy, was followed up through to 31 December 1987. Smoking, occupational history, chest x ray films, and data on lung function were available from clinical records for each member of the cohort. The overall cohort accounted for 10,956.5 person-years. The standardised mortality ratios (SMRs) for selected causes of death (International Classification of Diseases (ICD) eighth revision) were based on the age specific regional death rates for each calendar year. An excess of deaths for all causes (SMR = 1.40) was found, mainly due to chronic obstructive lung disease, silicosis, and tuberculosis with an upward trend of the SMR with increasing severity of the International Labour Office (ILO) radiological categories. Twenty two subjects died from lung cancer (SMR = 1.29, 95% confidence interval (95% CI) = 0.8-2.0). The risk increased after a 10 and 15 year latency but the SMR never reached statistical significance. No correlation was found between lung cancer and severity of the radiological category, the type of silica (coal or metalliferous mines, quarries etc), or the degree of exposure to silica dust. A significant excess of deaths from lung cancer was found among heavy smokers (SMR = 4.11) and subjects with airflow obstruction (SMR = 2.83). A nested case-control study was planned to investigate whether the association between lung cancer and airway obstruction was due to confounding by smoking. No association was found with the ILO categories of silicosis or the estimated cumulative exposure to silica. The risk estimate for lung cancer by airflow obstruction after adjusting by cigarette consumption was 2.86 for a mild impairment and 7.23 for a severe obstruction. The results do not show any clear association between exposure to silica, severity of silicosis, and mortality from lung cancer. Other environmental or individual factors may act as confounders in the association between silicosis and lung cancer. Among them, attention should be given to chronic airways obstruction as an independent risk factor for lung cancer in patients with silicosis.     

Silicosis mortality, prevention, and control--United States, 1968-2002

Silicosis is a preventable occupational lung disease caused by inhaling dust containing crystalline silica; no effective treatment for silicosis is available. Deaths from inhalation of silica-containing dust can occur after a few months' exposure (1). Crystalline silica exposure and silicosis have been associated with work in mining, quarrying, tunneling, sandblasting, masonry, foundry work, glass manufacture, ceramic and pottery production, cement and concrete production, and work with certain materials in dental laboratories. To describe patterns of silicosis mortality in the United States, CDC analyzed data from the National Institute for Occupational Safety and Health (NIOSH) National Occupational Respiratory Mortality System (NORMS) for 1968-2002. This report summarizes the results of that analysis, which indicated a decline in silicosis mortality during 1968-2002 and suggested that progress has been made in reducing the incidence of silicosis in the United States. However, silicosis deaths and new cases still occur, even in young workers. Because no effective treatment for silicosis is available, effective control of exposure to crystalline silica in the workplace is crucial.     

Meta-analysis of silicosis and lung cancer

OBJECTIVES: This study examined the association between silicosis and lung cancer in a systematic review (and meta-analysis) of the epidemiologic literature, with special reference to the methodological quality of observational studies. METHODS: We searched Medline, Toxline, BIOSIS and Embase (1966-May 2004) for original articles published in any language and systematically reviewed the bibliographies of the retrieved articles. Observational studies (cohort and case-control studies) were selected if they reported a measure of association [standardized mortality ratio (SMR), relative risk or odds ratio] relating lung cancer to silicosis. RESULTS: Thirty-one studies (27 cohort studies, 4 case-control studies) met the inclusion criteria of the meta-analysis. Without any adjustment for smoking, the meta-analysis of the cohort studies indicated that the common SMR was 2.45 [95% confidence interval (95% CI) 1.63-3.66; homogeneity P<0.0001]. When the results of the cohorts for which mortality data were adjusted for smoking were pooled, the common SMR was 1.60 (95% CI 1.33-1.93; homogeneity P=0.52). In a "dose-response" analysis, the profusion of small and large opacities found in chest X-rays correlated with the risk of death from lung cancer. Overall, the case-control studies were more conservative in their conclusions. CONCLUSIONS: Because of biases inherent to observational studies, it is likely that the risk of lung cancer among silicosis patients is overestimated in the current literature. There is nevertheless evidence, from data restricted to never-smokers and from a "dose-response" analysis, that silicosis and lung cancer are associated.