Past exposure to asbestos among active railroad workers

Before the transition from steam- to diesel-powered locomotives during the 1950s certain railroad workers had the opportunity for significant occupational exposure to asbestos. Past studies have demonstrated that older workers with jobs associated with the repair of steam locomotives had the most exposure. To determine the prevalence of currently employed railroad workers with past asbestos exposure we surveyed 514 white male employees of an active US railroad by mail questionnaire. Twenty-one percent (50/242) of the workers 50 years old or greater had likely asbestos exposure compared to 3% (9/275) of the workers 49 years old or less (p less than .001). Fifteen (30%) of the 50 older workers with likely asbestos exposure had current job titles no longer suggestive of past exposure. The duration of exposure of these older active workers was short, (median = 3 years; range, 6 months to 15 years). A history of past asbestos exposure may still be obtained among active railroad workers with past railroad shop employment.     

Lung function and exposure to asbestos among vehicle mechanics.

Vehicle mechanics (n = 99) exposed to asbestos (annual median value 0.08 f/ml), and local controls (n = 83) not occupationally exposed to asbestos were studied with regard to symptoms and pulmonary function. The inclusion criteria to participate in this study was an age of at least 40 years with no known exposure to lung irritating agents, and for the exposed subjects, more than 15 years occupational exposure to asbestos with at least 20 years from the first exposure. The subjects were studied during identical conditions by means of dynamic and static spirometry, single breath wash-out with nitrogen (N2) and carbon monoxide (CO). The median for cumulative exposure of asbestos during the entire work life among the studied mechanics was 2.3 f*y/ml. The mechanics had reduced transfer factor (TLCO), after adjustment for age, height, and smoking category. A significant dose-response relationship was noted between the cumulative exposure of asbestos and CV%. The findings suggest a slight influence of small airways and alveoli. The evaluation of the prognostic significance of this requires a longitudinal study.     

混苯作业人员脂质过氧化水平与抗氧化酶活性的研究

目的：探讨混苯对人体脂质过氧化的作用以及混苯作业人员早期损害的生物学检测指标。方法：选择133名长期从事喷漆作业的工人和169名无接尘、接毒史的工人为研究对象。用常规方法进行血红蛋白测定和白细胞计数,并对血清中MDA含量和SOD、GSH－Px活力进行测定。结果：两组间血红蛋白测定和白细胞计数的异常检出率无显著差异（P＞0．05）。MDA含量及其异常检出率两组间有显著性差异（P＜0．01）,且随着工龄的增长,接触组MDA含量明显增加（P＜0．05）。接触组SOD活性及其异常检出率较对照组明显增高（P＜0．01）,而GSH－Px活性和其异常检出率却显著下降（P＜0．01）。结论：长期接触低浓度混苯,将导致MDA含量和SOD活性增加及GSH-Px活性下降,且变化出现白细胞异常检出之前。     

Radiological evidence of asbestos disease among ship repair workers

Asbestos materials are now infrequently used in new ship construction. However, significant amounts were used in vessels constructed before 1975. As a consequence, for the next 30 or more years, the potential for asbestos exposure in the repair of such vessels will remain. We studied 286 workers who were 20 or more years from onset of employment in ship repair work. Eighty-six percent had radiological evidence of asbestosis, and five instances of previously undiagnosed lung cancer were found. This suggests that unless industrial hygiene precautions are taken in the future repair of vessels that have been built with asbestos, we will add additional decades to the legacy we already face as the result of uncontrolled shipyard exposures of the past.     

Gastrointestinal cancer mortality of workers in occupations with high asbestos exposures

Asbestos, which is a well-known risk factor for lung cancer and malignant mesothelioma, has also been suggested as a gastrointestinal (GI) carcinogen. This study was conducted to assess the relationship between high asbestos exposure occupations and the occurrence of GI cancer. Death certificate data were analyzed from 4,943,566 decedents with information on occupation and industry from 28 states from 1979 through 1990. Elevated proportionate mortality ratios (PMRs) for mesothelioma were used to identify occupations potentially having many workers exposed to asbestos. All PMRs were age-adjusted and sex- and race-specific. The PMRs for GI cancers in white males were then calculated for these occupations after excluding mesothelioma, lung cancer, and non-malignant respiratory disease from all deaths. We identified 15,524 cases of GI cancer in the 12 occupations with elevated PMRs for mesothelioma. When these occupations were combined, the PMRs for esophageal, gastric, and colorectal cancer were significantly elevated at 108 (95% confidence interval = 107–110), 110 (106–113), and 109 (107–110), respectively. Esophageal cancer was elevated in sheet metal workers and mechanical workers. Gastric cancer was elevated in supervisors in production and managers. Colorectal cancer was elevated in mechanical and electrical and electronic engineers. However, high exposure occupations like insulation, construction painter supervisors, plumbers, furnace operators, and construction electricians showed no elevations of GI cancers. In conclusion, this death certificate study supports an association between asbestos exposure and some GI cancer, however the magnitude of this effect is very small. Am. J. Ind. Med. 31:713–718, 1997. © 1997 Wiley-Liss, Inc.     

Respiratory morbidity in workers exposed to asbestos in the primary manufacture of building materials

Former employees (214) of a plant that manufactured asbestos-containing building materials (wallboard and acoustic tile) from 1958 through 1974 were screened for asbestos-related pulmonary disease. Results are presented on 182 union members whose names appeared on a 1966 seniority list in one of six departments believed to have had substantial asbestos exposure. The study population demonstrated a high frequency of pulmonary abnormalities often associated with asbestos exposure: low mean forced vital capacity percent of predicted (FVC % predicted), low mean forced expiratory volume at one second percent of predicted (FEV1 % predicted), presence of parenchymal abnormalities (40.1% with profusion scores of 1/0 or higher), and 30.5% with bilateral pleural abnormalities on chest roentgenograms. In addition, rales in two or more locations were found in 22.8% on examination of the chest, 30.6% gave a history of chronic bronchitis, and 34.8% of dyspnea grade two or higher. Calculated asbestos exposure scores, based upon participant recall, were not found to be associated with these abnormalities. The abnormal findings were not adequately explained by potential confounders such as cigarette smoking. Other notable findings in this study include the presence of smoking-adjusted decrements in pulmonary function associated with moderate profusion scores (i.e., 1/0 and 1/1) and the presence of a substantial degree of obstructive lung disease (19.2%) in this population.     

Roentgenographic evidence of asbestos exposure in a select population of railroad workers

A volunteer population of 266 current and former railroad workers was examined with posteroanterior and oblique chest roentgenograms, and a comprehensive occupational smoking history. Seventy-five percent of participants were over the age of 60, and 80% had fewer than 10 years of railroad-related asbestos exposure. Roentgenographic evidence of asbestosis was found in only six workers (2%), whereas 20% had one or more pleural changes. Radiological abnormalities were related to latency period, age, and occupation, but not to smoking habit. While selection factors qualify the results of this study, the findings support the exposure and suggest a past and future history of asbestos mortality and morbidity among steam era railway workers.     

镍接触作业工人抗氧化能力的研究

目的探讨职业性镍接触对工人抗氧化能力的影响。方法根据生产工艺的不同,选取某钢铁企业镍接触工人男性炼钢工、轧钢工及钢渣处理工共181人作为镍接触组,同时选择该企业的男性水处理工55人为对照组。黄嘌呤氧化酶法、化学比色法和硫代巴比妥酸法分别测定两组人群血清中总超氧化物歧化酶(SOD)活力、谷胱甘肽过氧化物酶(GSH-Px)活力和丙二醛(MDA)含量。结果不同工种镍接触组总SOD活力、GSH-Px活力和MDA含量分别与对照组相比,差异均有统计学意义(P0.05);不同工龄组总SOD活力、GSH-Px活力和MDA含量分别与对照组相比,除0～5 a组总SOD活力、GSH-Px活力分别与对照组相比,差异无统计学意义(P0.05)外,其他各年龄组差异均有统计学意义(P0.05);不同工龄组MDA含量分别与对照组相比,差异均有统计学意义(P0.05)。结论镍接触对工人抗氧化能力有影响,抗氧化酶活力降低,脂质过氧化产物增加。     

Alveolar fiber load in asbestos workers and in subjects with no occupational asbestos exposure: an electron microscopy study

The alveolar fiber load was evaluated by bronchoalveolar lavage and by scanning and transmission electron microscopy (SEM and TEM) in 50 subjects with or without occupational exposure to asbestos. The concentration of asbestos fibers in bronchoalveolar lavage was significantly higher in the groups of people currently and formerly occupationally exposed, compared to the concentration found in people only exposed environmentally, despite wide interindividual variation within the groups. Nonasbestos inorganic fibers were present in all groups, but the concentrations did not differ significantly. Both in people occupationally exposed and in those only environmentally exposed, the alveolar load consisted mainly of ultrashort and ultrathin fibers, which can be studied only with TEM. In fact, the percentage of fibers greater than 5 micron long was only around 15% in the occupationally exposed and was minimal in those only environmentally exposed. The geometric mean diameters of asbestos fibers retained in the alveoli ranged from 0.05 micron for chrysotile to 0.15 micron for amphiboles.     

Cancer mortality and incidence of mesothelioma in a cohort of wives of asbestos workers in Casale Monferrato, Italy

BACKGROUND: Family members of asbestos workers are at increased risk of malignant mesothelioma (MM). Although the hazard is established, the magnitude of the risk is uncertain, and it is unclear whether risk is also increased for other cancers. Few cohort studies have been reported. OBJECTIVE: The "Eternit" factory of Casale Monferrato (Italy), active from 1907 to 1986, was among the most important Italian plants producing asbestos-cement (AC) goods. In this article we present updated results on mortality and MM incidence in the wives of workers at the factory. METHODS: We studied a cohort of 1,780 women, each married to an AC worker during his employment at the factory but not personally occupationally exposed to asbestos. Cohort membership was defined starting from the marital status of each worker, which was ascertained in 1988 from the Registrar's Office in the town where workers lived. At the end of follow-up (April 2003), 67% of women were alive, 32.3% dead, and 0.7% lost to follow-up. Duration of exposure was computed from the husband's period of employment. Latency was the interval from first exposure to the end of follow-up. RESULTS: The standardized mortality ratio (SMR) for pleural cancer [21 observed vs. 1.2 expected; SMR = 18.00; 95% confidence interval (CI), 11.14-27.52] was significantly increased. Mortality for lung cancer was not increased (12 observed vs. 10.3 expected; SMR = 1.17; 95% CI, 0.60-2.04). Eleven incident cases of pleural MM were observed (standardized incidence ratio = 25.19; 95% CI, 12.57-45.07). CONCLUSIONS: Household exposure, as experienced by these AC workers' wives, increases risk for pleural MM but not for lung cancer.     

二甲基甲酰胺作业工人皮肤污染量研究

Objective To establish a method for the determination of dimethylformamide(DMF) and investigate dermal contamination and absorption among workers occupationally exposed to DMF. Method 37 workers exposed to DMF were divided randomly into two groups. DMF was washed down by isopropyl alcohol in A group (16 workers) and water in B group(21 workers).Gas chromatography was used for the quantification of dermal contamination and N-methylformamide(NMF) in urine, correlative study was done between them. Results DMF could be detected in all samples in A group, but could not be detected in B group. The miscel-laneous peaks could be completely separated from the DMF peak in the sample spectrum, without matual in-ference. The highest degree of total dermal contamination was observed in wet spinning workshop[(2.84±1.31 ) ing], postprocessing workshop[(2.50±0.95) mg] and dry spinning workshop[( 1.95±0.61) mg] were lower. The respiratory cumulative exposure dosages were 351.3, 201.3 and 135.2 mg respectively. The average DMP concentration in air of the third printing processing workshop, the dry spirning workshop and the wet spinning workshop was 60.2, 89.6, 156.4 mg/m3 respectively, and the respiratory tract contamination in the workers of the three workshops were 135.2, 201.3 and 351.3 mg respectively. There was statistical independence between the quantification of total dermal contamination and NMF in urine (r=0.176,P>0.05). Conclusion Isopropyl alcohol is the effective washing solvent.When the concentration of DMF in workplace air is above the occupa-tional exposure limit, respiratory tract absorption is the principal pathway of DMF absorption,but dermal con-tamination of DMF should not be ignored.     

Difficulties of attribution of effect in workers exposed to fiberglass and asbestos.

Man-made mineral fibers have many properties of asbestos that raise concern about their safety. We studied 175 fiberglass production workers, using chest radiographs, measurement of total lung capacity, chest examinations, and occupational and medical histories. Pulmonary volumes and flows were calculated as percent of predicted, adjusted for height, age, ethnicity, and cigarette smoking. Thirty-one men with radiographically evident small irregular opacities of profusion of 1/0 or greater and/or pleural abnormalities were observed. Eight of 38 men with such changes said they had been exposed only to fiberglass; the other 23 with radiologically detectable pleural and/or pulmonary changes were among the 137 whose histories indicated that they had been exposed to asbestos and to fiberglass. Pulmonary function measurements as group means were reduced in the 175: FVC was 94.8% predicted, FEV1 was 91.3% predicted, FEF25-75 was 80.7% predicted, FEF75-85 was 73.1% predicted and FEV1/FVC was 0.73. Total lung capacity (TLC) was elevated to 114.2% predicted (mean) and RV/TLC (mean 0.46) was also elevated. Although only 78% of fiberglass production workers gave histories of asbestos exposure, all had shared the air in a manufacturing plant where ovens insulated with asbestos were continuously cleaned, repaired, dismantled, and rebuilt. It appears that attribution of the effects of their exposure to fiberglass could not be estimated independently of the effects of asbestos exposure.     

二甲基甲酰胺作业工人皮肤污染量研究

Objective To establish a method for the determination of dimethylformamide(DMF) and investigate dermal contamination and absorption among workers occupationally exposed to DMF. Method 37 workers exposed to DMF were divided randomly into two groups. DMF was washed down by isopropyl alcohol in A group (16 workers) and water in B group(21 workers).Gas chromatography was used for the quantification of dermal contamination and N-methylformamide(NMF) in urine, correlative study was done between them. Results DMF could be detected in all samples in A group, but could not be detected in B group. The miscel-laneous peaks could be completely separated from the DMF peak in the sample spectrum, without matual in-ference. The highest degree of total dermal contamination was observed in wet spinning workshop[(2.84±1.31 ) ing], postprocessing workshop[(2.50±0.95) mg] and dry spinning workshop[( 1.95±0.61) mg] were lower. The respiratory cumulative exposure dosages were 351.3, 201.3 and 135.2 mg respectively. The average DMP concentration in air of the third printing processing workshop, the dry spirning workshop and the wet spinning workshop was 60.2, 89.6, 156.4 mg/m3 respectively, and the respiratory tract contamination in the workers of the three workshops were 135.2, 201.3 and 351.3 mg respectively. There was statistical independence between the quantification of total dermal contamination and NMF in urine (r=0.176,P>0.05). Conclusion Isopropyl alcohol is the effective washing solvent.When the concentration of DMF in workplace air is above the occupa-tional exposure limit, respiratory tract absorption is the principal pathway of DMF absorption,but dermal con-tamination of DMF should not be ignored.     

Cancer mortality among workers exposed to amphibole-free chrysotile asbestos.

The issue of whether exposure to chrysotile asbestos alone, without contamination from amphibole asbestos, causes lung cancer and mesothelioma was investigated in a 25-year longitudinal study (1972-1996) in Chongqin, China. The study cohort comprised 515 male asbestos plant workers exposed to chrysotile only; the control cohort included 650 non-dust-exposed workers. The results of analysis in which the proportional hazards model was used indicated that mortality due to all causes, all cancers, and lung cancer was related to asbestos exposure; the relative risks, adjusted for age and smoking, were 2.9, 4.3, and 6.6, respectively. Fiber concentrations in the raw material section and the textile section of the plant were 7.6 and 4.5 fibers/ml, respectively. Because of differences between the study and control plants, the authors also compared various sections of the asbestos plant that had different levels of dust exposure. The adjusted relative risk of lung cancer was 8.1 for workers exposed to high versus low levels of asbestos. Two cases of malignant mesothelioma, one pleural and the other peritoneal, were found in the asbestos cohort. These results suggest that heavy exposure to pure chrysotile asbestos alone, with negligible amphibole contamination, can cause lung cancer and malignant mesothelioma in exposed workers.     

Occupational asbestos exposure among respiratory cancer patients in Lithuania

BACKGROUND: Despite intensive use of asbestos, no cancer case has ever been diagnosed as asbestos related in Lithuania. This paper attempts to estimate the proportion of those occupationally exposed to asbestos among respiratory cancer patients. MATERIAL AND METHODS: Occupational exposure to asbestos was assessed retrospectively for 298 lung cancer and four mesothelioma patients, admitted to the Institute of Oncology, Vilnius. The evaluation was based on personal interview data using an internationally established questionnaire covering most likely activities of asbestos exposure at the workplace. Cumulative exposure to asbestos at work was estimated in fiber years. Lung tissue asbestos fiber burden analysis was conducted by scanning transmission electron microscopy on 23 samples. RESULTS: A cumulative asbestos exposure of > or =25 fiber years was found for 10 lung cancer patients (3.4%). They worked in foundries, construction, installation, shipyard, power plant, railway, asbestos cement, glass and chemical industry. In a further 56 lung cancer patients (18.8%) and for one (25%) mesothelioma patient, a cumulative exposure from 5 to 24.9 fiber years was assessed. Asbestos fibers were detected in 18 cases, the burden ranged from 0.1 to 4.1 million fibers/g dry lung tissue; concentrations exceeding 1 million f/g dry lung tissue were found in four cases. All fibers were chrysotile. CONCLUSIONS: Findings indicate that a fraction (3.4%) of the lung cancer cases could be attributed to heavy occupational exposure to asbestos using the Helsinki criterion of > or =25 fiber years. Therefore, approximately 50 lung cancer cases per year in Lithuania could be asbestos-related compensable occupational diseases.