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Port Allegany Asbestos Health Program: a community response to a public health problem.

The Port Allegany Asbestos Health Program (PAAHP) is a unique, community-run program that resulted from the successful cooperative efforts of a labor union, a corporation, community health care providers, and a medical school. PAAHP's goal is to develop a permanent community health organization that will use the most advanced existing knowledge to mitigate the adverse health effects anticipated as a result of the use of amosite asbestos in a Port Allegany, Pa. factory. All 1,188 persons employed by the factory during the years 1964-72 and the 3,000-4,000 persons in household contact with them are eligible for the program. PAAHP's major services are intensive medical surveillance, smoking cessation assistance, health education for participants, and continuing education for area physicians about asbestos-related diseases. One of the program's policies is not to disturb the usual patterns of medical care. If further testing or treatment is needed, patients are referred to their usual personal physicians. PAAHP does not provide ordinary medical care or medical insurance. Across the nation, the number of workers estimated to have been exposed to asbestos is more than 20 million, and their household contacts are estimated to be about three to four times that number. Adverse health effects resulting from asbestos exposure include elevated risk of lung cancer, mesothelioma, gastrointestinal tumors, and asbestosis. The problem requires the development of public health solutions. PAAHP has demonstrated the feasibility of a community-based model as one useful approach.

Asbestos↗

Transfer RNA breakdown products in the urine of asbestos workers.

Patients with malignant mesothelioma, a neoplasia strongly associated with previous asbestos exposure, excrete in the urine high levels of modified purines, pyrimidines, and their ribosides, breakdown products of transfer RNA. The urinary excretion levels of modified nucleosides were measured in 47 male insulation workers with long term exposure to asbestos and, therefore, at high neoplastic risk. The nucleoside levels of 44 male control subjects were used for comparison. Asbestos-related radiographic changes were found in 70% of the exposed individuals. An increasing severity of radiographic alterations was associated with a greater frequency of elevated nucleoside clusters, especially in m'A, m'I, m'G, and m2(2)G. Duration since onset of exposure was directly related to pseudouridine, m'I, and m2(2)G. Though cigarette smoking contributes to the development of asbestos-related lung cancer, data are presented that support the hypothesis that asbestos exposure is the more important factor related to the elevated values of nucleosides. It was concluded, therefore, that measuring nucleoside levels in populations at high risk of developing certain kinds of cancer may provide a useful diagnostic tool for detecting "preclinical" biochemical changes that may be predictive of future neoplastic manifestations.

Adult↗

Sister chromatid exchange frequency in asbestos workers.

In vitro cytogenetic studies of amosite, chrysotile, and crocidolite asbestos have shown that these fibers may induce chromosome abnormalities and an elevated sister chromatid exchange (SCE) rate in mammalian cells. Twenty-five asbestos insulators (6 with radiographic asbestosis) were compared to 14 controls frequency matched for age and were found to have a marginally increased SCE rate in circulating lymphocytes with increasing years of exposure (P= 0.057). There was a significant association between SCE rate and smoking (P=0.002) after controlling for years of asbestos exposure and age. Smoking asbestos insulators had the highest SCE rate. Sister chromatid exchanges in chromosomes of group A, i.e., the group with the longest chromosomes, were significantly associated with asbestos exposure and cigarette smoking, with an interaction between the two.

Asbestos↗

Prevalence and incidence of benign asbestos pleural effusion in a working population.

Benign asbestos effusion was defined by (1) exposure to asbestos, (2) confirmation by roentgenograms or thoracenteses, (3) no other disease related to pleural effusion, and (4) no malignant tumor within three years. There were 34 benign effusions among 1,135 exposed workers compared with no otherwise unexplained effusions among 717 control subjects. Prevalence was dose related with 7.0%, 3.7%, and 0.2% effusions with severe (III), indirect (II), and peripheral (I) exposure, respectively. The latency period was shorter than for other asbestos-related disorders. Benign effusion was the most common asbestos-related abnormality during the first 20 years after exposure. Incidence studies showed 9.2 effusions per 1,000 person-years for level III exposure, 3.9 for level II, and 0.7 for level I. Most effusions were small; 28.6% recurred, and 66% were asymptomatic. There was one mesothelioma six years after effusion. Asbestos exposure should be carefully searched for in patients with "idiopathic" pleural effusion.

Adult↗

Interstitial accumulation of inhaled chrysotile asbestos fibers and consequent formation of microcalcifications.

Previous studies have shown that inhaled chrysotile asbestos impacts initially at the bifurcations of alveolar ducts in the lungs of rats. Asbestos fibers are transported through alveolar epithelial cells at these bifurcation regions to the interstitium during the 24-hour period after a 1-hour exposure. To further these studies, white rats were exposed to an aerosol of chrysotile asbestos for 1 hour. Animals were sacrificed, and the lungs were fixed by vascular perfusion immediately after and 1 month after exposure. Blocks of tissue were prepared for light and electron microscopy. We report here, at 1 month after exposure, that numerous asbestos fibers had accumulated within the lung interstitium at alveolar duct bifurcations. Many of these interstitial fibers were found in te center of intracellular microcalcifications. The presence of calcifications was proven by X-ray energy spectrometric analysis of the inclusions in situ. Clear X-ray peaks for calcium and phosphorus were demonstrated. The authors propose that 1 month after a 1-hour exposure to chrysotile asbestos, fiber-induced membrane injury in cells of the lung interstitium leads to formation of microcalcifications. This may represent the presence of early cell injury in the initial pathogenetic sequence of asbestosis.

Aerosols↗

[Evaluation of the size of the population occupationally exposed to asbestos dust and the incidence of asbestosis in Poland 1970-1980].

The analysis was based on the data on occupational exposure to asbestos dust obtained from sanitary--epidemiological stations and cards of occupational diseases certification collected at the Institute of Occupational Medicine in Lódź. The approximate number of those occupationally exposed to asbestos dust in national economy as a whole was about 6400 persons (excluding the data on the Polish State Railways, Ministry of National Defence, Ministry of Internal Affairs) of this--3000 persons worked at concentrations exceeding TLV values for the dust containing asbestos. Approx. 2200 subjects worked at workplaces where no dust concentrations measurements were made. Mostly this work was performed periodically, casually, for varying daily or monthly number of hours. The highest exposure rates were those of the provinces of Lódź, Jelenia Góra and Gdańsk (up to 1980), Warszawa and Katowice. In seventeen provinces there is not a single workplace with asbestos dust. During 1970-1980, 143 cases of asbestosis were found in Poland, of this--49% women. The length of employment in asbestos dust exposure of those with diagnosed asbestosis came, on average, to 20 years (92%) worked more than 10 years, 48% more than 20 years).

Air Pollutants↗

Environmental asbestos concentrations in the United States.

Measurements were made of chrysotile concentrations in buildings with asbestos-lined return air plenums, in buildings with damaged asbestos surfacing material, in the houses of asbestos workers, and around buildings while asbestos-containing fireproofing material was being sprayed on steelwork. The data obtained demonstrate significant environmental contamination by asbestos: 43/89 air samples exceeded 50 ng/m3, although only 2/89 samples exceeded 1000 ng/m3. These findings should prompt appropriate control or remedial action.

Air↗

Construction occupations, asbestos exposure, and cancer of the colon and rectum.

Colorectal cancer affects more than 157,000 Americans annually. Occupational risk from exposure to asbestos dust has been implicated, leading us to explore further the possible association between colorectal cancer and asbestos. Two hundred sixty-one cases of colon and rectal cancer and 183 control cases were identified within a large, population-based case-control study conducted in southeast Michigan. Employment in occupations historically known to involve heavy exposure to asbestos was used as a surrogate for asbestos exposure. Cancers of the colon showed reduced odds ratios. Our findings differ substantially from those of the previous studies showing elevated risk. Further study is needed to address the same question, with specified asbestos exposure assessment and control for potentially significant confounders such as physical activity and diet.

Adult↗

[Asbestos-related lesions detected by high-resolution CT scanning in asymptomatic workers. Specificity, relation to the duration of exposure and cigarette smoking].

The possibility to detect initial "preclinical" pulmonary lesions related to asbestos is under debate. The aim of this study is to report our experience. We have submitted to HRCT 70 shipyard workers with chest X-ray judged "normal" by "outside" readers (mean age 44.5 +/- 6.1 ys) with a similar grade of (low-level) exposure to amosite (mean duration of "direct"/"heavy" exposure was 4.2 +/- 4.9 ys; "environmental"/"light" exposure was 8.4 +/- 5.9 ys). Among the 70 workers, in 34 pleural plaques were shown, in 6 subjects parenchymal abnormalities alone and in 13 parenchymal and pleural abnormalities were found; in the last 17 workers no pathological finding was shown. In six subjects the presence of a combination of parenchymal abnormalities permitted us to diagnose asbestosis. The difference in the duration of exposure to asbestos for the subjects with both pleural and parenchymal involvement compared to all other groups of workers was statistically significant; also the difference in duration of exposure between workers with or without parenchymal involvement resulted significant. In a control group (20 subjects without any known professional exposure to asbestos) HRCT permitted us to identify 5 cases with small pleural plaques while only one case presented parenchymal bands; lesion frequency was significantly lower in comparison with the exposed group. Calcified plaques have been proved to be more common in the workers with heavier exposure, and no one of the reference group had calcified plaques. The CT-determined emphysema score was found to optimally correlate with smoking habit (pack/years). In conclusion our study suggests that pulmonary or pleural involvement can be shown by HRCT before the onset of any clinical symptomatology with high sensitivity and specificity. Furthermore the results seem to indicate that the prevalence of HRCT-shown parenchymal lesions and the severity of lung involvement among asbestos-exposed workers are related to the duration of exposure, as in most of clinically evident asbestos-related lung disorders, in contrast with previous observations.

Adult↗

[Tumor necrosis factor alpha in bronchoalveolar lavage fluid and its production by alveolar macrophages with asbestos exposure].

It is generally accepted that asbestos exposure causes pulmonary fibrosis and carcinogenesis. Several studies have suggested that TNF alpha is produced principally by mononuclear phagocytes and that it may play a role in inflammation, fibrosis and anti-tumor activity. We studied TNF alpha production by alveolar macrophages and the TNF alpha concentration in bronchoalveolar lavage fluid harvested from asbestos-exposed subjects and healthy controls. TNF alpha production by alveolar macrophages was significantly higher in the asbestos-exposed subjects than in healthy controls (3696 +/- 1606, 1938 +/- 753 pg/ml; p < 0.01). The period from first exposure correlated inversely with TNF alpha production (r = -0.6; p < 0.05). The TNF alpha concentration in bronchoalveolar lavage fluid was also significantly higher in the asbestos-exposed subjects than in healthy controls. These results suggest that abnormal TNF alpha production by alveolar macrophages may be related to fibrosis and carcinogenesis due to asbestos.

Adult↗

Pulmonary complications of asbestos exposure.

Except for benign pleural effusion, asbestos-related pulmonary complications, including asbestosis, malignant mesothelioma and bronchogenic carcinoma, usually occur more than 20 years after exposure. Pleural plaques and pleural thickening serve as markers for asbestos exposure, but they are not associated with an increased risk of malignancy. Clinical criteria for the diagnosis of asbestosis include a reliable history of asbestos exposure, an appropriate interval between exposure and disease detection, radiographic evidence of pulmonary fibrosis, decreased vital capacity and diffusing capacity, and bilateral posterior inspiratory crackles. A lung biopsy is indicated only to rule out other causes of interstitial lung disease. A history of dyspnea, pleuritic chest pain, fatigue, weight loss and pleural effusion in a former asbestos worker is suggestive of mesothelioma. Cigarette smoking greatly increases the risk of lung cancer in asbestos workers.

Asbestos↗

Quantitative importance of asbestos as a cause of lung cancer in a Swedish industrial city: a case-referent study.

We wanted to assess the quantitative importance of asbestos as a cause of lung cancer. In a case-referent study, the exposure to asbestos, tobacco smoke and some other occupational exposures were compared between 147 cases of lung cancer (100 men, 47 women), 111 hospital referents, and 109 population referents, all below the age of 75 yrs and living in an industrial city. The attributable risk of lung cancer due to asbestos exposure was 16% in men (95% confidence interval 1-31%). No woman had occupational exposure to asbestos. We conclude that in the mid 1980's tobacco smoking was the major attributable risk, being 95% for men and 78% for women, but that in men asbestos was an appreciable contributing factor in the general population of a Swedish industrial city.

Adult↗

[Detection of asbestos in thoracic lymph nodes in patients with asbestosis].

To detect a possible lymph transport of inhaled asbestos fibres and fragments from the human lung we examined via light and scanning electron microscope a total of 224 intrapulmonary, extrapulmonary and paratracheal lymph nodes of 6 postmortem cases and 3 lung resectates from patients with histologically proven pulmonary asbestosis. The lymph nodes were subdivided into 3 groups and examined separately. We found partly sharp-edged staff-shaped and partly amorphous dust particles that were mostly embedded in phagolysosomes of macrophages, using energy-dispersive x-ray microanalysis; these particles yielded a spectrum like that of asbestos, which means they must be identified as asbestos fragments. Besides these, typical asbestos bodies and asbestos needles were also identified.

Aged↗

Exporting asbestos: disease and policy in the developing world.

The health effects of asbestos are well known, with lung cancer, mesothelioma and asbestosis recognized as the most common causes of mortality and morbidity among exposed populations. Recognition of these hazards coupled with an explosion of litigation against asbestos manufacturers brought by injured workers has resulted in declining markets for this commodity in the U.S. and other Western democracies. With Western markets for asbestos decreasing, the developing world has become the target of asbestos exporters in an attempt to revitalize an industry in decline. This paper discusses the trends in worldwide asbestos markets over the last two decades and the serious health implications of policies directed at establishing viable markets for this commodity in developing nations.

Asbestos↗

[Epidemiologic survey of pleural plaques among inhabitants of Matsubase exposed to asbestos].

A high prevalence of pleural plaques (41.5%, 148/357) was found during a mass screening for lung cancer in Matsubase town in 1988. The inhabitants of this town were carefully studied each year from 1988 to 1993. The vast majority (81.2%) of inhabitants over the age of 20 years underwent chest roentgenography at least once during this period. Pleural plaques were detected by CT in 938 subjects, which is 17.3% of those studied and 4.1% of the total population. A total of 89 had an occupational history of asbestos exposure, 64 (71.9%) of whom had pleural plaques. However, these subjects with occupational exposure accounted for only 6.8% of the 938 subjects, and therefore most of the pleural plaques seemed to have been caused by general environmental exposure. The incidence of plaques was greater in older subjects: among those in the seventh decade of life it was more than eight times higher than among those in the fourth decade of life. Anthophyllite was detected in the main asbestos mill. The concentrations of asbestos fibers in the air and water near the old asbestos mills and factories were not high. The death rates and the adjusted mortality rates due to lung cancer in Matsubase were lower than in surrounding towns and lower than in Kumamoto prefecture as a whole. These results indicate that there is now no environmental contamination by asbestos fibers in Matsubase town. No cases of malignant mesothelioma have been confirmed in this town during the past 17 years.

Adult↗

[Lung cancer mortality in Casale Monferrato (Italy) and attributable risk to occupations in the asbestos-cement production].

The study presents mortality rates for lung cancer in the town of Casale Monferrato, where the largest Italian asbestos cement-plant was located. Cases of lung cancer dying in 1989-94 were exhaustively searched for in the register of deaths. Each case of lung cancer has been identified as ever or never employed in the factory with a linkage to the rosters of employees in the plant. Women were also identified as ever or never married to an asbestos-cement worker. The number of person-years at risk for asbestos cement workers and their wives was measured on the basis of the most recent follow-up. Mortality rates were computed separately for those exposed (workers and wives of workers) and for those with no evidence of exposure. Mortality rates for non-exposed were similar to rates in Piedmont (the region where Casale is located). The relative risk (ever exposed vs. never exposed) was 2.8 among men and 2.1 among women. Attributable risk among the exposed was 64.5% for men and 53.1% for women while among the general population it was 18.1% for men and 13.2% for women. The study confirms the dramatic effect of occupational asbestos exposure in Casale Monferrato but does not suggest an increase in lung cancer mortality among people with no occupational activity in the asbestos-cement production.

Adult↗

Respiratory effects of occupational exposure to asbestos.

Ventilatory capacities of 73 Libyan men working in the Asbestos-Cement Pipe factory in Jenzur, a residential area near Tripoli, Libya and those of 73 age-matched healthy Libyan men unexposed to asbestos were determined. The mean values of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) for men unexposed to asbestos were 3.89 +/- 0.084 and 3.64 +/- 0.082 liters respectively. The respective values for men exposed to asbestos were 3.62 +/- 0.082 and 3.29 +/- 0.097 liters. Thus, there has been a significant decrease in the ventilatory function of the men exposed to asbestos as compared with age-matched unexposed counterparts.

Adult↗

Asbestos bodies in the sputum of workers exposed to environmental pollution.

The diseases related to asbestos exposure (pulmonary fibrosis, broncogenic carcinoma and mesothelioma) are of widespread interest and involve different socio-economic groups of subjects. Since these pathologies have a wide diffusion in the industrial world, we carried out an investigation on two populations occupationally exposed to air pollution and asbestos fibre inhalation (164 traffic policemen of the municipal district of Rome and 218 railwaymen) and on a control group (119 residents in a rural district of Perugia) for the detection of asbestos bodies in the sputum. The results obtained from traffic policemen and railwaymen workers differred significantly from those of the control group. The presence of asbestos bodies in traffic policemen seems to be determined by a strong synergetic effect between gaseous urban pollution, cigarette smoking habits and asbestos dust arising from car brakes and building materials, whereas, in railwaymen it seems to be more directly correlated to exposure.

Adult↗