Exposures and mortality among chrysotile asbestos workers. Part II: mortality

A retrospective cohort mortality study was conducted among a cohort of 1,261 white males employed one or more months in chrysotile asbestos textile operations and followed between 1940 and 1975. Statistically significant excess mortality was observed for all causes combined (standardized mortality ratio [SMR] = 150), lung cancer (SMR = 135), diseases of the circulatory system (SMR = 125), nonmalignant respiratory diseases (SMR = 294), and accidents (SMR = 134). Using estimated fiber exposure levels in conjunction with detailed worker job histories, exposure-response relationships were investigated. Strong exposure-response relationships for lung cancer and asbestos related non-malignant respiratory diseases were observed. Compared with data for chrysotile miners and millers, chrysotile textile workers were found to experience significantly greater lung cancer mortality at lower lifetime cumulative exposure levels. Factors such as differences in airborne fiber characteristics may partially account for the large differences in exposure response between textile workers and miners and millers.     

接触温石棉女工恶性肿瘤死亡的队列研究

目的调查接触温石棉女工的恶性肿瘤死亡率。方法以1960年1月1日至1980年12月31日曾经从事家庭内温石棉手工纺织作业一年以上的女工为调查对象,采用历史性队列流行病学方法进行研究。结果在5681名接触温石棉纺织女工中,有144名死于癌症,其中有74名女工死于肺癌,病死率最高;其次为肝癌,死亡数为27例;占第三位的是胃癌,死亡数为18例。以当地女性年龄组别恶性肿瘤死亡率均值为对照组计算标准化死亡比(SMR),所有除肺癌外的恶性肿瘤与肺癌的SMR分别为1.16(P<0.05)和4.17(P<0.01)。结论接触温石棉的女性纺织工人有明显的肺癌死亡高发倾向。     

Cancer mortality among workers exposed to formaldehyde

Proportionate mortality among workers exposed to formaldehyde was analyzed among employees of a large chemical plant in Western Massachusetts. Twenty-four such decedents, all males, were identified through union records, reports of former coworkers, and a systematic review of obituaries in local newspapers. Work histories were obtained from seniority lists. Race-age-sex-adjusted proportionate mortality ratios (PMRs) were significantly elevated for cancer of the colon based on United States. county, and county cancer mortality proportions (PMR = 702, 424, 333, p ≤ 0.05). as were PMRs for the category buccal and pharyngeal cancer (PMR = 870, 952, 833. p < 0.05). This study provides evidence of formaldehyde's carcinogenicity. These findings are at variance with a previous report of the mortality experience of workers at the same plant from an earlier period.     

Bronchoalveolar lavage fluid cellular profile in workers exposed to chrysotile asbestos

The cellular profile of bronchoalveolar lavage fluid (BALF) in asbestos-exposed population remains controversial. We, therefore, aimed to investigate BALF in apparently healthy individuals that were exposed in asbestos-related work for a long period of time. Participants were selected among employees of a car brakes and clutches factory that used chrysotile asbestos. Selection criteria were an employment history of ≥ 15 years and the absence of severe respiratory disease. The total number and type of BALF cells, the existence of dust cells, iron-laden macrophages and asbestos bodies were assessed. Thirty-nine workers (25 men), with a mean age of 46.2 ± 4.2 years and a mean employment time of 23.5 ± 4 years, participated. Asbestos bodies were observed in 14 out of 39 (36%) specimens, dust cells in 37 and iron-laden macrophages in all. Those with asbestos bodies had at least 3 times higher probability to have lymphocytosis (lymphocytes > 11%: 64% vs 28%, p = 0.027) and had an increased percentage of iron-laden macrophages compared to those without asbestos bodies (median values: 42% vs 13%, p = 0.08). Smokers (36%) had less lymphocytes compared to non and ex-smokers (median values: 6% vs. 13%, p = 0.002), and iron-laden macrophages count had a positive relation (r = 0.31, p = 0.05) to lymphocyte count. Asbestos-exposed asymptomatic individuals with the presence of asbestos bodies in the BALF are more likely to have lymphocytic alveolitis while concurrent dust exposure and smoking habits hold a significant role.     

Cancer mortality among electric utility workers exposed to polychlorinated biphenyls.

OBJECTIVES: To assess whether excess mortality from cancer, malignant melanoma of the skin, and cancers of the brain and liver in particular, is associated with long term occupational exposure to polychlorinated biphenyls (PCBs). METHODS: An epidemiological study of mortality was conducted among 138,905 men employed for at least six months between 1950 and 1986 at five electrical power companies in the United States. Exposures were assessed by panels composed of workers, hygienists, and managers at each company, who considered tasks performed by workers in 28 job categories and estimated weekly exposures in hours for each job. Poisson regression was used to examine mortality in relation to exposure to electrical insulating fluids containing PCBs, controlling for demographic and occupational factors. RESULTS: Neither all cause nor total cancer mortality was related to cumulative exposure to PCB insulating fluids. Mortality from malignant melanoma increased with exposure; rate ratios (RRs) relative to unexposed men for melanoma were 1.23 (95% confidence interval (95% CI) 0.56 to 2.52), 1.71 (0.68 to 4.28) and 1.93 (0.52 to 7.14) for men with < 2000, > 2000-10,000, and > 10,000 hours of cumulative exposure to PCB insulating fluids, respectively, without consideration of latency. Lagging exposure by 20 years yielded RRs of 1.29 (0.76 to 2.18), 2.56 (1.09 to 5.97), and 4.81 (1.49 to 15.50) for the same exposure levels. Mortality from brain cancer was modestly increased among men with < 2000 hours (RR 1.61, 95% CI 0.86 to 3.01) and > 2000-10,000 hours exposure (RR 1.79, 95% CI 0.81 to 3.95), but there were no deaths from brain cancer among the most highly exposed men. A lag of five years yielded slightly increased RRs. Mortality from liver cancer was not associated with exposure to PCB insulating fluids. CONCLUSIONS: This study was larger and provided more detailed information on exposure than past investigations of workers exposed to PCBs. The results suggest that PCBs cause cancer, with malignant melanoma being of particular concern in this industry.     

Cancer mortality among workers exposed to chemicals during uranium processing.

Data provided by the Comprehensive Epidemiology Data Resource allowed us to study patterns of cancer mortality as experienced by 3814 uranium-processing workers employed at the Fernald Feed Materials Production Center in Fernald, Ohio. Using risk-set analyses for cohorts, we estimated the effects of exposure to trichloroethylene, cutting fluids, and kerosene on cancer mortality. Our results suggest that workers who were exposed to trichloroethylene experienced an increase in mortality from cancers of the liver. Cutting-fluid exposure was found to be strongly associated with laryngeal cancers and, furthermore, with brain, hemato- and lymphopoietic system, bladder, and kidney cancer mortality. Kerosene exposure increased the rate of death from several digestive-tract cancers (esophageal, stomach, pancreatic, colon, and rectal cancers) and from prostate cancer. Effect estimates for these cancers increased with duration and level of exposure and were stronger when exposure was lagged.     

Cancer incidence and mortality among workers exposed to acrylonitrile

A cohort of 1,083 male employees who had potential for exposure to acrylonitrile between 1944 and 1970 at a Du Pont textile fibers plant were followed through 1981 for mortality and through 1983 for cancer incidence. In total, the 21 cancer deaths were fewer than expected based on either Du Pont or U.S. rates. No significant excesses were seen by primary site. In all, 37 cancer cases occurred as compared with 36.5 expected based on company rates. Five lung cancer cases were observed and 6.9 expected. There were 5 prostate cancer cases as compared with 1.9 expected. Of these, 4 occurred among wage employees during the 1975-1983 period, compared to 0.9 expected. This excess was statistically significant.     

Correlation between radiological and functional findings in workers exposed to chrysotile asbestos

The relationship between the extent of respiratory disease from chest radiographs and the severity of functional impairment was assessed in 185 workers with long-term exposure to asbestos in an asbestos-cement factory. The workers were divided into seven subgroups according to functional abnormality findings (restrictive, obstructive, mixed restrictive-obstructive, reduced diffusion capacity, increased diffusion capacity, small airway disease and normal). Restrictive functional abnormality was present in 29% of the workers, obstructive and mixed in 3% small airway disease in 4%, reduced diffusion capacity in 4% increased diffusion capacity in 7%, while the remaining 49% were normal. The subjects with radiological diffuse pleural disease were characterized by FVC reduction, whereas in those with mixed pleural-parenchymal radiological abnormalities both FVC and DLCO were reduced. FVC and DLCO decrements correlated well with the increasing grades of profusion according to the ILO classification. In the group of workers with normal chest radiographs and normal spirometry, a decrease or increase in lung diffusion capacity for CO (DLCO) was an isolated finding. In addition, a correlation existed between the length of exposure and functional parameters (reduced FVC and DLCO, while FEV1/FVC increased with longer exposure). The study shows that reduced lung function indices can be found in subjects without radiological evidence for parenchymal asbestosis (ILO grade 1/1 profusion or greater). The results suggest that asbestos exposure, in addition to lung diffusion capacity decrease, can be accompanied by an increase in lung diffusion capacity.     

中国石棉接触人员癌症死亡队列研究的Meta分析

目的以M eta分析探讨单纯接触温石棉人员癌症是否高发。方法凡满足明确是中国石棉接触人员且为癌症死亡率队列研究的资料均被纳入研究对象,以直接法与随机效应模型法计算主要部位癌症标准化死亡比(SMR)及其95%可信区间(CI),计算Q统计量与Z值检验研究结果异质性及其来源。结果共有13个队列符合入选标准,平均间皮瘤死亡百分比为0.62%,全死因、全癌亡、肺癌的M eta-SMR显著上升(分别为1.51、1.96、4.54),单纯接触温石棉人员肺癌的M eta-SMR也显著上升(4.39),消化系统、喉、乳腺和生殖泌尿系统等其他部位癌症的M eta-SMR未见显著上升。结论单纯温石棉暴露能使作业人员肺癌、间皮瘤显著高发,与其他部位癌症无病因联系。     

Fiber size and number in workers exposed to processed chrysotile asbestos, chrysotile miners, and the general population

We analyzed chrysotile and chrysotile-associated amphibole (largely tremolite) asbestos fibers in 21 workers exposed to various types of processed (milled) chrysotile ore, 20 long-term chrysotile miners, and 20 members of the general population (controls). Significantly greater amounts of both chrysotile and tremolite were found in processed-ore workers and miners than in controls. On average, the mean fiber lengths and aspect ratios for the mining and processed-ore-exposed workers were similar and were significantly greater than the values seen in the controls; within the processed-ore group, there was a marked variation in these parameters, and some workers appeared to be exposed to fairly long, thin fibers. It was found empirically that the fiber size data, and to a lesser extent the concentration data, could be used to classify workers accurately into those with processed-ore exposure and controls. We conclude that fiber sizes in the lungs of processed-ore-exposed workers are similar to those of chrysotile miners and are considerably longer than those found in the general population; some processed-ore workers have longer fibers which might be responsible for higher disease incidences in certain working groups; tremolite accompanies chrysotile in a variable proportion of workers exposed to processed chrysotile products and might be important in the genesis of mesothelioma in such workers; and mineralogic analysis will usually detect exposure even when chrysotile has largely disappeared from lung tissue.     

手纺温石棉女工肿瘤死亡的41年队列研究

采用历史性队列研究方法对手纺温石棉女工肿瘤死亡情况进行了研究 ,以寿命表法计算人年数 ,以观察人群人年数为基数计算死亡率 ,并以当地女性年龄别死亡率均值为对照计算标准化死亡比 (SMR)、相对危险度 (RR)和特异危险度 (AR)及其 95%可信区间 (CI)。调查发现 ,在对 1960～ 1980年间手纺温石棉 1年以上的 5681名女工 ,追访至 2 0 0 0年底 ,共死亡 858例 ,以肿瘤死亡为主 (2 13例 ,占 2 4 83 % ) ,其中又以肺癌居首位 (87例 ,占 40 85% ) ,死亡率分别为 12 7 47 10万与 52 0 6 10万 ,SMR各为 1 3 5(1 18～ 1 54)、3 88(3 14～ 4 79) ,AR各为 3 3 0 7 10万与 3 8 64 10万 ,均显著高于对照 (P <0 0 5或P <0 0 1)。结果提示 ,手纺温石棉作业能使接触人员肺癌高发 ,与“闪石理论”、“矿物油暴露理论”和吸烟无关 ,而是由于手纺作业更易产生长度大于 10 μm的石棉纤维所致     

石棉接触人员消化系统癌症死亡队列研究的Meta分析

目的 以Meta分析探讨石棉接触者消化系统癌症是否高发.方法 凡满足明确是石棉接触人员且为消化系统癌症死亡率队列研究的资料均被纳入研究对象,以直接法与随机效应模型法计算消化系统主要部位癌症标准化死亡比(SMR)及其95%可信区间(CI),计算Q统计量与Z值检验研究结果异质性及其来源.结果 共有69个队列符合入选标准,单纯接触温石棉、温石棉与闪石类石棉混合作业的人员,全死因、全癌亡、消化系统癌症和胃癌的meta-SMR明显上升,SMR分别为1.16、1.42、1.15、1.20,差异均有统计学意义(P<0.01).胃癌meta-SMR明显升高,主要见于石棉水泥工、采选矿工与绝缘工SMR分别为1.27,1.21与2.13,差异均有统计学意义(P<0.05).敏感性分析提示,Meta分析结果是稳健的.食管、结肠、直肠、肝等其他消化系统部位癌症的meta-SMR未见明显上升.结论 石棉暴露似能使作业人员胃癌明显高发,与其他消化系统部位癌症无病因联系.     

Follow-up study of chrysotile asbestos textile workers: Cohort mortality and case-control analyses

Previous studies of mortality among white males employed in a Charleston, South Carolina asbestos textile plant using chrysotile demonstrated significant excess mortality due to asbestos-related disease and a steep exposure-response relationship for lung cancer. This cohort was further studied by adding 15 years of follow-up and including mortality among white female and black male workers. Nested case-control analyses were undertaken to further explore possible differences in lung cancer risk by textile operation as well as possible confounding by mineral oil exposures. Preliminary data for white males have been previously published. White males experienced statistically significant excess mortality due to lung cancer (standardized mortality ratio [SMR] = 2.30; confidence interval [CI] = 1.88–2.79), all causes (SMR = 1.48; CI = 1.38–1.58), all cancers (SMR = 1.50; CI = 1.29–1.72), diabetes mellitus (SMR = 2.05; CI = 1.18–3.33), heart disease (SMR = 1.41; CI = 1.26–1.58), cerebrovascular disease (SMR = 1.50; CI = 1.08–2.02), pneumoconiosis and other respiratory diseases (SMR = 4.10; CI = 3.10–5.31), and accidents (SMR = 1.49; CI = 1.15–1.91). Among white females, statistically significant excesses occurred for lung cancer (SMR = 2.75; CI = 2.06–3.61), all causes (SMR = 1.21; CI = 1.11–1.32), pneumoconiosis and other respiratory diseases (SMR = 2.40; CI = 1.53–3.60), and other respiratory cancers (SMR = 14.98; CI = 4.08–38.7). Among the total cohort of black males, the only statistically significant excess observed was for pneumoconiosis (SMR = 2.19; CI = 1.23–3.62). Based on historical exposure measurements at the plant, there was a positive exposure-response relationship for both lung cancer and pneumoconiosis. Data for the entire cohort demonstrate an increase in the lung cancer relative risk of 2–3% for each fiber/cc-year of cumulative chrysotile exposure. This relationship was more consistent for the white male workers. The excess risk for lung cancer among white males and females appeared to occur at cumulative exposures lower than those for black males. Possible reasons for the lesser lung cancer risk among black males include less smoking and differences in airborne fiber characteristics experienced by black males as a result of plant job placement patterns. The case-control analysis found employment in preparation and carding operations (where most of the black males worked) to be associated with a slightly reduced lung cancer risk, although not statistically significant, whereas spinning and twisting employment was associated with a statistically significant increased lung cancer risk compared to other plant operations. Airborne fiber size data, determined by transmission electron microscopy, demonstrated slightly longer fibers in spinning and twisting compared to other textile operations. Case-control analyses demonstrated little effect of mineral oil exposures on the lung cancer exposure-response estimates. Two deaths due to mesothelioma were observed among this cohort.     

Tyler asbestos workers: mortality experience in a cohort exposed to amosite

OBJECTIVES: To examine the causes of death among 1130 former workers of a plant in Tyler, Texas dedicated to the manufacture of asbestos pipe insulation materials. This cohort is important and unusual because it used amosite as the only asbestiform mineral in the production process. High level exposure of such a specific type was documented through industrial hygiene surveys in the plant. METHODS: Deaths were ascertained through various sources including data tapes from the Texas Department of Health and the national death index files. As many death certificates as possible were secured (304/315) and cause of death assigned. After select exclusions, 222 death certificates were used in the analysis. Causes of death were compared with age, race, and sex specific mortalities for the United States population with a commercial software package (OCMAP Version 2.0). RESULTS: There was an excess of deaths from respiratory cancer including the bronchus, trachea, and lung (standardised mortality ratio (SMR) 277 with 95% confidence interval (95% CI) 193 to 385). Four pleural mesotheliomas and two peritoneal mesotheliomas were identified. The analysis also showed an increasing risk of respiratory malignancy with increased duration of exposure including a significant excess of total deaths from respiratory cancer with less than six months of work at the plant (SMR 268 with 95% CI 172 to 399). CONCLUSIONS: The importance of the cohort lies with the pure amosite exposure which took place in the plant and the extended period of latency which has followed. The death certificate analysis indicates the pathogenicity of amosite, the predominant commercial amphibole used in the United States. These data confirm a link between amosite asbestos and respiratory malignancy as well as mesothelioma.