Analysis of mortality in chrysotile asbestos miners in China

In order to investigate the mortality of a cohort of chrysotile asbestos miners in China and evaluate its association with exposure to chrysotile,a fixed cohort of 1932 workers in chrysotile asbes-tos mine was established in 1981 and followed till June 1,2010.Information on vital status,cause of death and smoking habits was collected.The workers were divided into two groups according to their exposure status.The exposed group was composed of frontline workers who worked directly on mining or processing asbestos products.The control group consisted of those who were not directly exposed to asbestos in their work.Standardized mortality ratio (SMR) was calculated according to Chinese national death rates.Cox proportional hazards model was applied to estimate the adjusted relative risks of deaths from major causes in exposed and control groups.The results of this study showed that main causes of mortality were malignant neoplasm,cardiovascular disease,cerebrovascular disease and respiratory disease for chrysotile miners.The mortality rate was 939.20 per 100 000 person-years for workers.The SMR for all causes of death was 1.46 in the cohort.Statistically significant mortality excesses were found for lung cancer (SMR=1.51),pulmonary heart disease (SMR=2.70),respiratory disease (SMR=1.93),asbestosis (SMR=9.62),and accident (SMR=1.59).The mortalities from malignant neo-plasm,lung cancer,cerebrovascular disease and digestive disease in the exposed group were signifi-cantly higher than those in the control group.The findings indicate that chrysotile exposure is a risk factor for lung cancer,respiratory disease,cerebrovascular disease and digestive disease.     

Cohort Mortality Study in Three Ceramic Factories in Jingdezhen in China

To investigate the health impacts of crystalline silica mixed dust and other potential occupational hazards on workers in ceramic factories, a cohort study of 4851 workers registered in the employment records in 3 ceramic factories in Jingdezhen city of China between 1972 and 1974 was identified. The cohort mortality was traced throughout 2003 with an accumulation of 128970.2 person-years, revealed 1542 deaths. Standardized mortality ratios （SMRs） were calculated for the main causes of death by using Chinese national mortality rates as reference. The mortality from all causes in three ceramic factories was 12.0‰ and the cumulative mortality was 31.8%. Malignant neoplasm, cardiovascular diseases, respiratory diseases, infectious diseases were the first four illnesses that threaten workers’ life, and they accounted for 73.2% of all deaths. The results of this study showed that the standardized mortality ratio for all subjects was 1.02, which is very close to that expected on the basis of the China national mortality rates. Statistically significant mortality excesses for respiratory disease （SMR=1.36）, pneumoconiosis （SMR=37.34）, infectious disease （SMR=5.70） and pul- monary tuberculosis （SMR=3.88） were observed. The mortality of 2938 dust-exposed workers was higher than that of 1913 non dust-exposed workers. Except for pneumoconiosis, the mortality from lung cancer, non-malignant respiratory diseases and pulmonary tuberculosis in dust-exposed workers were significantly increased as compared with that in non-exposed workers, and the relative risks （RRs） were 1.86 （1.16–2.99）, 2.50 （1.84–3.40）, 1.81 （1.34–2.45）. The exposure-response relationships between cumulative dust exposure level and mortality from all causes, colorectal cancer, lung cancer, respiratory diseases, and pulmonary tuberculosis were also identified. The findings indicated that silica mixed dust in ceramic factories has harmful impact on the workers’ health and life span in ceramic factory.     

Cancer mortality and asbestosis among workers in an asbestos plant in Chongqing, China

Objective To investigate whether asbestosis is a risk factor for mortality of lung cancer. Methods A fixed cohort study was established in an asbestos plant in Chongqing, China, and followed up for 30 years from the beginning of 1972. Basic personal information on life state, cause of death, and diagnosis of asbestosis was collected. Multiple logistic regressions were applied to analyze risk factors. Results During the 30-year follow-up, 584 male workers constituting a total of 14 664 person-years were monitored and data were analyzed. Among them, 203 （34.8%） died and the mortality rate was 13.8 per 1000 person-years, cancer accounting for 37.4%. Excess risks were observed for lung cancer （OR=3.72） and nonmalignant respiratory diseases （OR=2.73） among workers with asbestosis. High-exposure level was another risk factor for lung cancer （OR-3.20）. Workers with category II of asbestosis demonstrated a higher OR of both lung cancer and nonmalignant respiratory diseases than those with category I of asbestosis. Conclusion High asbestos exposure level and asbestosis were the risk factors for death of lung cancer and nonmalignant respiratory diseases. Asbestosis is an independent risk factor for lung cancer among Chinese workers exposed to chrysotile, the risk increases with the increasing profusion of opacities of lung.     

A 20-year follow-up study on the effects of long-term exposure to thorium dust

Objective The purpose of this study is to investigate the possible effects of long-term exposure to dust containing thorium and thoron progeny dust-exposed miners. Methods A negative, high voltage, exhaled thoron progeny measurement system was used to estimate the miners’ thorium lung burden. Results The highest thorium lung burden of 638 miners was 11.11 Bq. The incidence of stage 0+ pneumoconiosis was higher among dust-exposed miners. Lung cancer mortality of the dust-exposed miners was significantly higher than that of controls (P<0.005). Conclusion There is a difference in cancer rates between those who have long-term exposure to dust containing thorium (in which carcinogenic ThO2 and SiO2 exist) and thoron progeny and those who have not.     

Cohort Studies on Cancer Mortality Among Workers Exposed Only to Chrysotile Asbestos： a Meta-analysis

Objective To determine whether there was excessive risk of cancer among workers exposed to chrysotile fiber alone by applying a meta-analysis technique. Methods All data meeting the criteria of cohort studies on cancer mortality among workers exposed only to chrysotile were incorporated into meta-analysis. Pooled standardized mortality ratios (SMRs) and their corresponding 95% confidence intervals (CIs) for main cancer sites were calculated using two approaches of unweighted ratio and random effect model. The heterogeneity and its sources of the results were examined with a Q-statistic and Z-score test. The dose-response effect as reflected in the percentage of all deaths due to mesothelioma served as a proxy measure of chrysotile exposure. Results A cohort of twenty six workers exposed to chrysotile alone was summarized. The significantly elevated meta-SMRs for all deaths (1.27), all cancers (1.28), cancers of respiratory organs (2.51), cancers of lung (2.35) and cancers of stomach (1.24) were observed. The significantly elevated meta-SMRs for lung cancer within occupational strata were observed among textile workers (3.55), asbestos product manufacturers (3.30), miners and millers (2.24), cement product workers (1.22), and for stomach cancer among asbestos product manufacturers (1.49). Meta-SMRs for cancers at other sites were not significant. Meta-SMR for lung cancer showed an increasing trend with an elevated percentage of all deaths from mesothelioma, but no such trend for stomach cancer. Conclusion There are excessiverisks of lung cancer and mesothelioma among workers exposed to chrysotile fiber alone, and likely no convincing indication of an etiological association between chrysotile exposure and cancers at other sites.     

Epidemiologic Study of Cancer Mortality among Chloroprene Workers

Both case-control and cohort studies were undertaken from July 1,1969 to June 30,1983 toascertain whether exposure to chloroprene increases the risk of cancer.Fifty-five cases of cancerdeaths were verified,16 of which had histories of exposure to chloroprene ranging from 3 to 23years(median 11 years)with a latent period of 8-27 years,except for one case of 3 years(median12.5 years).Fifty-four pairs were obtained by matching the cancer deaths to noncaneer deathsin accordance with strict requirements.The odds ratio for the paired data was 13,x~2=8.64,P<0.005.The average age at death from cancer of workers exposed to chloroprene was 12.7 yearsyounger than that of unexposed workers,t'=2.98,P<0.001.The total cohort consisted of1213 persons,among whom 149(11.6%)had histories of exposure for over 25 years,381(31.5%)for over 20 years,and 852(70.2%) for over 15 years.The SMR for the total cohort was 2.38(P<0.01),and all SMRs for the high-exposure occupations were of significance(P<0.05orP<0.01),in contrast to those of the low-exposure groups whose SMRs were low or zero.Thus,a dose-response relationship existed.Among the high-exposure occupations,maintenance me-chanics seem to have the highest risk of cancers,and SMRs for liver,lung,and lymphatic cancerswere significant in this group.These results suggested that chloroprene exposure increases therisk of developing cancer.1989 Academic Press,Inc.     

Silicosis in Automobile Foundry Workers: A 29-Year Cohort Study

Objectives The purposes were to determine the relationship between silicosis among foundry workers and their cumulative exposure to silica dust, and to establish a regression model to predict the risk for developing silicosis by a given length of employment and air concentrations of silica at worksites. Methods A 29-year cohort study was conducted, including all those employed for more than one year during January 1, 1980 to December 31, 1996 and all members of the cohort were followed-up to December 3 1, 2008. In total, 2 009 workers of an automobile foundry in Shiyan, Hubei province were recruited in the study, 1 300 at eight worksites including sand preparation, cast shakeout, and finishing, melting, moulding, core-making, overhead crane operation and pouring as exposed group, and the other 709 auxiliary workers at the same factory, such as electricians, inspectors, fitters, and so on, as control group. Person-years of observation were calculated by persons observed and years followed-up for each of them. Person-year incidence of silicosis and its relative risk （RR） or odds ratio （OR） and 95% confidence intervals （CI） among the workers were estimated, adjusted for relevant factors with logistic regression model using SPSS version 15.0 software. Results Totally, 2 009 workers were followed-up for 37 151 person-years and 48 cases of silicosis were found, with an overall incidence of 1.34 per thousand, 2.02 per thousand in exposed group, and 0.15 per thousand in control one. Risk of silicosis was significantly higher in the exposed group than that in the control one （RR=13.13, 95% CI 3.18-54.13）, higher in men than that in women （RR=13.92, 95% CI 1.92-100.93）. Risks of silicosis varied by job, highest in those exposed to cast shakeout and finishing （RR=28.14, 95% CI 6.43-123.11）, followed by those exposed to pouring （RR-22.23, 95% CI 5.01-98.55） in the foundry. Average length of employment at onset of silicosis was 25.94 years, and silicosis incidence increased with length of employment. Average age at onset of silicosis was 47.83 years old. The risk of silicosis in workers with pulmonary tuberculosis was 2.57 folds as those without it （P〈0.01）. Ten deaths were recorded in those with silicosis, with a case-fatality rate of 20.83 percent three of them died of lung cancer, three of liver cancer, two of ischemic heart disease, and two of other diseases as their immediate causes of death. Incidence of silicosis in foundry workers positively correlated with their cumulative silica exposure （OR-3.00, 95% CI 2.34-3.83）. Risks of silicosis increased by 4.38 folds with an increase of 1 mg/m^3-year of cumulative silica exposure, and by 3.79 folds with smoking, respectively, adjusted for alcohol drinking and age. Based on a logistic regression model fitted, incidence of silicosis is expected to be 44.6 per thousand for those with daily exposure to silica of 4.18 mg/m^3 in average for 30 years, and if incidence of silicosis is expected to be less than 1 per thousand, daily exposure to silica should be controlled below 0.2 mg/m^3 for those with 20 years of employment, or below 0.1 mg/m^3 for those with 30 or 40 years of silica exposure. Conclusions At present, foundry workers in China still face high risk of developing silicosis. For lowering occurrence of silicosis in exposed workers, it seems necessary that current occupational exposure limits for silica at worksites in China should be reexamined and silica dust control measures be strengthend.     

A Case—Contrl Study of Dietary Factors in Patients with Lung Cancer

A case-control study was designed to investigate association of dietary factors with the risk of lung cancer in Sichuan,China.The cases consisted of 135 patients with preinvasive lung cancer which had been confirmed with histopathology,fiber bronchoscope,CT and X-ray film in three provincial hospitals in the recent one year.Controls were healthy subjects who went to one of these hospitals for health check-up;patients with pulmonary diseases was exluded.Controls were matched to cases for sex and age with a ratio of 1:1.Nutrient intakes, the eating habit and other relevant factors were investigated.The data analyzed with the conditional logistic regression model indicated,that dietary beta-carotene intakes had a significantly inverse association with the risk of lung cancer.Vitamin Chad a less significantly inverse association with the risk.Association of protein,fat,energy,retinol intakes of dietbalance index with the risk was not significant.Association of tea,alcohol,garlic or mushroom,respectively,with the risk was also not observed.Consumption of more processed foods and deep-fried foods were found to be risk factors.Smoking and air pollution from coal burning stoves were also observed as independent risk factors of lung cancer in the present study.The mental stress incidence in the case was significantly higher than that in the control.     

Idiopathic pulmonary fibrosis will increase the risk of lung cancer

Objective To review the studies investigating the increased risk of lung cancer in patients with idiopathic pulmonary fibrosis （IPF）.Data sources Data cited in this review were obtained mainly from PubMed and Medline from 1999 to 2013 and highly regarded older publications were also included.Study selection We identified,retrieved and reviewed the information on the frequency,risk factors,anatomical features,histological types,clinical manifestations,computed tomography findings and underlying mechanisms of lung cancer in IPF patients.Results The prevalence rates of lung cancer in patients with IPF （4.8％ to 48％） are much higher than patients without IPF （2.0％ to 6.4％）.The risk factors for lung cancer in IPF include smoking,male gender,and age.Lung cancers often occur in the peripheral lung zones where fibrotic changes are predominant.Adenocarcinoma and squamous cell carcinoma are the most common types of lung cancer in patients with IPF.Radiologic features of these patients include peripherally located,ill-defined mass mimicking air-space disease.The underlying mechanisms of the development of lung cancer in patients with IPF have not been fully understood,but may include the inflammatory response,epithelial injury and/or abnormalities,aberrant fibroblast proliferation,epigenetic and genetic changes,reduced cell-to-cell communication,and activation of specific signaling pathways.Conclusions These findings suggest that IPF is associated with increased lung cancer risk.It is necessary to raise the awareness of lung cancer risk in IPF patients among physicians and patients.     

Trend Analysis of Cancer Mortality in the Jinchang Cohort,China, 2001-2010

Objective To describe the baseline data of cancers in the Jinchang Cohort, this paper examined trends in cancer mortality among adults investigated in Jinchang, Gansu province from 2001 to 2010.
Methods Mortality data were collected from company departments through administrative documents, death certificates, etc. Trend analyses of cancer mortality were performed on the basis of 925 cancer deaths between 2001 and 2010.
Results The crude mortality rate of cancer continuously increased from 161.86 per 100,000 in 2001 to
315.32 per 100,000 in 2010, with an average increase of 7.69%per year in the Jinchang Cohort (16.41%in females compared to 6.04% in males), but the age-standardized mortality rate increased only in females. Thirteen leading cancers accounted for 92.10%of all cancer deaths. The five leading causes of cancer mortality in males were lung, gastric, liver, esophageal, and colorectal cancer, whereas those in females were lung, liver, gastric, breast, and esophageal cancer.
Conclusion The overall cancer mortality rate increased from 2001 to 2010 in the Jinchang Cohort, with greater rate of increase in females than in males. Lung, breast, and gastric cancer, in that order, were the leading causes of increased cancer mortality in females.     

Expression of Hsp27 and Hsp70 in lymphocytes and plasma in healthy workers and coal miners with lung cancer

In coal mines, main occupational hazard is coal-mine dust, which can cause health problem including coal workers' pneumoconiosis and lung cancer. Some heat shock proteins (Hsps) have been reported as an acute response to a wide variety of stressful stimuli. Whether Hsps protect against chronic environmental coal-mine dust over years is unknown. It is also interesting to know that whether the expression of Hsp27 and Hsp70 proteins as a marker for exposure is associated risk of lung cancer among coal miners. ...     

氡子体致肺癌作用及与其他暴露因素间作用形式的研究

应用前瞻性队列研究方法，对云锡高危人群氡子体致肺癌作用及与其他暴露因素间作用形式进行了探讨。结果表明：调整年龄、粉尘或砷暴露后，随累积氡子体暴露量（ＷＬＭ）增大、暴露年限越长、首次氡子体暴露年龄越小患肺癌的危险性越大。结果支持氡子体是云锡矿工肺癌病因因素的假说。分析没有发现氡子体与吸烟、粉尘、砷暴露、慢性支气管炎史之间有相乘的交互作用。     

Lung cancer mortality among nonsmoking uranium miners exposed to radon daughters

Radon daughters, both in the workplace and in the household, are a continuing cause for concern because of the well-documented association between exposure to radon daughters and lung cancer. To estimate the risk of lung cancer mortality among nonsmokers exposed to varying levels of radon daughters, 516 white men who never smoked cigarettes, pipes, or cigars were selected from the US Public Health Service cohort of Colorado Plateau uranium miners and followed up from 1950 through 1984. Age-specific mortality rates for nonsmokers from a study of US veterans were used for comparison. Fourteen deaths from lung cancer were observed among the nonsmoking miners, while 1.1 deaths were expected, yielding a standardized mortality ratio of 12.7 with 95% confidence limits of 8.0 and 20.1. These results confirm that exposure to radon daughters in the absence of cigarette smoking is a potent carcinogen that should be strictly controlled.     

Radiographic abnormalities and the risk of lung cancer among workers exposed to silica dust in Ontario.

OBJECTIVE: To determine whether workers in Ontario who had been exposed to silica dust and who have radiographic abnormalities are at increased risk of lung cancer. DESIGN: Cohort and case-control studies of rates of death from lung cancer and cancer incidence rates; data were obtained from the Ontario Silicosis Surveillance Registry. Follow-up was through linkage to the Ontario mortality and cancer registries. SETTING: Ontario. PARTICIPANTS: A total of 523 workers with radiographic abnormalities and 1568 control subjects with normal radiographic findings who had been exposed to silica dust. Matching criteria were year of birth and the requirement that the control subject have a normal radiographic finding either later than or in the same year that the radiographic abnormality was identified in the silicosis subject. OUTCOME MEASURES: Standardized mortality ratios (SMRs), standardized incidence ratios (SIRs) and odds ratios for lung cancer. RESULTS: In the cohort analysis, with the Ontario population rates as reference, the all-cause SMR was 0.96 among the workers with radiographic abnormalities and 0.51 among the control subjects. The corresponding SIRs for lung cancer were 2.49 and 0.87 (p < 0.001). In the case-control analysis the workers with silicosis were more likely than the control subjects to have been smokers, but this difference likely accounted for only a small part of the difference in the incidence of lung cancer. The relative risk of lung cancer was elevated among the workers with silicosis from the foundry, mining and nonmetallic-minerals industries; however, the number of subjects was too small for a significant difference to be detected. Among the miners exposure to radon daughters did not affect the risk of lung cancer attributable to radiographic abnormalities. CONCLUSIONS: Radiographic abnormalities suggestive of exposure to silica dust are markers for increased risk of lung cancer. Physicians might thus wish to warn their patients with silica-associated radiographic abnormalities about the increased risk and to counsel those who smoke to stop.     

广州市居民肺癌死者的职业分析

根据1982年广州市全人口肺癌死者个案调查及人口普查资料,分析了职业因素对广州市居民肺癌死亡率的影响,结果表明:产业工人的标化死亡比(SMR)高于脑力劳动者;接触有害物质的工种,可使男性鳞癌的 SMR 增加,但对女性则未见到接触有害物质使鳞癌 SMR 高于腺癌 SMR 的倾向。吸烟与否对男性肺癌的职业 SMR 有所影响,然而对女性的影响却不明显。全人群中家务劳动者与干部的肺癌人群特异危险度(PAR)高于其他职业,可能与他们在全人口中所占比例较大有关。     

某热电厂回顾性队列死亡调查──10年随访

虽然有许多文章评价火力发电厂对周围环境的危害，但是很少关于直接接触粉尘、高温、噪声、毒物等有害因素对电厂职工健康影响的报道，为了查明这些因素对电厂职工死亡率和肿瘤死亡率有没有影响，我们对某热电厂进行了１０年回顾性队列调查研究，结果１６２４人组成的队列，１０年提供１５４１３．７３人年，死亡５２人，其中１６人死于恶性肿瘤，队列全死因死亡率稍低于本市居民人口（ＳＭＲ＝０．７８，９５％可信限０．５６～０．９９）（健康工人效应）。实际肿瘤死亡人数与按本市居民肿瘤死亡率计算的预期死亡人数比较未见明显差异（ＳＭＲ＝０．９８，９５％可信限０．５６～１．６０）。然而比较电厂内部各组ＳＭＲ，发现锅炉最高，“机、炉、电、热”次之，不接尘组第三，行政第四，接尘组最低，提示电厂粉尘危害与高温、噪声、电磁场、职业紧张等危害因素有联合作用。可能会影响恶性肿瘤死亡率。     

乌鲁木齐市居民1991～1992年恶性肿瘤职业人群分布

目的：了解乌鲁木齐市不同职业人群中恶性肿瘤的分布特征，为进一步探讨某些职业环境与恶性肿瘤的关系收集基础资料。方法：收集本市居民当中１９９１～１９９２年恶性肿瘤死亡资料，按国家统计局规定的职业人群分类标准，将人群分组，用标化死亡比（ＳＭＲ）指标评价各职业人群恶性肿瘤死亡率水平。结果：国家机关企事业负责人及办事员、建筑工人、驾驶员、采矿工人、化学工人、橡胶塑料工人、皮革皮毛及玻璃陶瓷工人肺癌ＳＭＲ分别为１．５６、５．９６、１．８６、４．９０、９．０９、１４．９３、２０．４１、１８．８７，并都具有统计学显著性差异（Ｐ＜０．０５）。建筑工人、采矿工人及电气安装工人胃癌ＳＭＲ分别为３．７２、４．６９和３．３６，也具有显著的统计学意义（Ｐ＜０．０５）。而专业技术人员中肺癌、肝癌及胃癌的ＳＭＲ分别只是０．１２、０．２１及０．３０（Ｐ＜０．０５）。结论：肺癌在国家机关、企事业负责人及办事员、建筑工人、驾驶员、采矿工人、化学工人、橡胶塑料工人、皮革皮毛工人和玻璃陶瓷工人中明显高于一般人群。胃癌在建筑工人、采矿工人及电气安装工人中多见。各类专业技术人员中肺癌、肝癌及胃癌死亡率明显低于一般人群。     

石棉工人的肺癌调查

作者调查了省内两个石棉矿和一个石棉厂共2383例工人的恶性肿瘤,尤其是肺癌的发生率。采用回顾性队列调查法,追踪10年。结果肺癌标化死亡比(SMR)为2.66(P<0.05),相对危险度(RR)10.36(P<0.01),均有显著性差异。肺癌的潜伏期平均23.8年,主要发生在高石棉粉尘浓度的工种,表明肺癌的发生与接触石棉密切相关。