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PubMed1999

[Is there criteria to allow the selection of patients exposed to asbestos which is relevant to thoracic computed tomography screening?].

OBJECTIVE: This study was undertaken to determine whether certain criteria could be used to select among asbestos-exposed subjects those who could benefit from computed tomography screening. MATERIALS AND METHODS: Search for criteria enabling the selection of patients who should undergo a CT screening exam after occupational exposure to asbestos was conducted in 150 subjects. All subjects were explored with selected high-resolution CT scans. Studied parameters were age, exposure data, pulmonary function test results. RESULTS: None of the exposure data or pulmonary function test results suggested with certainty the presence or absence of asbestos-related pleural and parenchymal lung disease. The studied parameters could not be used to select patients who could benefit from CT screening. CONCLUSION: None of the studied parameters enabled a selection of asbestos-exposed subjects who should undergo chest CT screening.

Adult↗

PubMed1989

Bilateral pleural plaques in Corsica: a marker of non-occupational asbestos exposure.

In north-east Corsica, asbestos outcrops are a source of environmental pollution, as assessed by airborne concentrations of chrysotile and tremolite that are significantly higher in the north-east than the north-west. For this reason we compared the frequencies of patients with asbestos pleural plaques in these 2 regions by checking the X-rays of 1721 patients born in north Corsica who had not undergone any occupational exposure to asbestos. The percentage of plaques was respectively 3.7% in the north-east, and 1.1% in the north-west (p less than 0.05). The relative risk of 3.3 demonstrates a strong relationship between environmental asbestos and the pleural plaques found in north-east Corsica.

Aged↗

PubMed1984

Effects of two international union against cancer standard reference samples of asbestos on cultured rabbit ovarian surface epithelial cells.

To evaluate their interaction with asbestos, rabbit ovarian surface epithelial cells were exposed in vitro to amosite or Rhodesian chrysotile fibers (5.0 micrograms/ml). The morphology of these cells was studied by phase-contrast, scanning and transmission electron microscopy. Amosite fibers up to 10 micron in length were phagocytized by surface cells within 24 hours. Internalization of amosite fibers occurred prevalently over microvilli-rich regions of the cell surface and, after 4 days, the intracytoplasmic localization of these fibers was most often perinuclear. In contrast with amosite, chrysotile fibers were less frequently phagocytized. Instead, they caused focal cell membrane damage, intracytoplasmic vacuolization and cell clumping. A different effect of the two asbestos fibers was also observed when estimates of cell growth were obtained in replicate cultures exposed to fibers before cell confluence. In contrast with asbestos-free cultures which underwent a 4.3 fold increase in cell number, cells exposed to amosite displayed nearly a 7-fold numerical increase (ca. 160% of controls; P less than 0.05). Cells maintained in presence of chrysotile grew 3.5 fold (approximately 80% of controls). When administered at the time of cell plating, both mineral fibers (chrysotile greater than amosite) significantly depressed cell growth. These data indicate that amosite and chrysotile asbestos can have cytotoxic or proliferative effects on ovarian surface epithelial cells. Further investigation is required to ascertain if susceptibility of these cells to mineral fiber injury may play a role in the genesis of proliferative ovarian surface lesions.

Animals↗

PubMed1993

Environmental pleural plaques in an asbestos exposed population of northeast Corsica.

The purpose of this study was to determine whether the inhabitants of villages environmentally exposed to asbestos, in northeast Corsica, had a higher incidence of pleural plaques. X-rays were obtained from subjects aged over 50 yrs, with no occupational exposure to asbestos or history of pleural disease, in one village exposed to asbestos, Murato, and a nonexposed, control village, Vezzani. In addition, the mineral content of the air and parietal pleura of animals in the exposed zone was studied, using transmission electron microscopy. The incidence of bilateral pleural plaques in the exposed population was 41%, as compared to 7.5% in the nonexposed population (p < 0.00001). The levels of airborne tremolite were higher in Murato (6-72 ng.m-3) than in Vezzani (< 1 ng.m-3), but chrysotile levels were similar. Significant numbers of chrysotile and tremolite fibres were identified in the parietal pleura of animals from the exposed village. This study confirms the well-known correlation between bilateral pleural plaques and environmental exposure to low levels of asbestos.

Aged↗

PubMedDate not supplied

[Occupational exposure to asbestos in removal and protective treatment of roof coverings].

In the Province of Varese several operations have been carried out in the last two years for the removal or overcovering of asbestos-cement roofings. The present study assessed the level of exposure of the operators to inhalable asbestos fibres. The concentrations of asbestos fibres were determined by optic and electronic microscope analysis: the analyses showed the presence of mixtures of chrysotile and amosite in varying proportions. The exposure levels were correlated with the work procedures. In handling materials, there is not only fibre dispersion but sometimes also the production of asbestos-cement fragments, which can release inhalable fibres several days later. In order to limit both personal and environmental risk, it is essential to observe the rules of caution and good practice.

Air Pollutants, Occupational↗

PubMed1998

Asbestos-related x-ray changes in foundry workers.

Michigan has a statewide mandatory occupational disease reporting system. As part of that system, reports are received from hospital, physicians, death certificates, the worker's compensation bureau, and company medical departments. Based on this reporting, the State of Michigan has a special emphasis program for the surveillance of silicosis, a known disease outcome among foundry workers. From 1985-1996, 115 cases reported to the State Surveillance System as silicosis, pneumoconiosis not specified, or pulmonary fibrosis were reclassified as having asbestos related x-ray changes after a B-reader interpretation of each case's chest x-ray. During this same period there were an additional 697 reports confirmed as silicosis and 6,724 cases reported to the surveillance system as asbestosis. Among the 115 reports reclassified as having asbestos-related x-ray changes without evidence of silicosis-related x-ray changes, 54 had worked in foundries. Only 7 (14.8%) of these individuals had their primary work in maintenance in the foundry; 40 (85.1%) had their primary foundry work in a production job; and for 10 individuals the occupation was not known. Asbestos has been used in foundries on pipe laggings, boiler coverings, as insulation in fan housings, in gloves, aprons and curtains, as insulation in cupolas, and in ladles and insulation in sand molds. Clinicians caring for foundry workers need to be aware that asbestos-related x-ray changes are not uncommon in this population and asbestos exposure should be considered as one of the carcinogens contributing to the known increased risk of lung cancer among foundry workers.

Aged↗

PubMed2000

Laryngeal and hypopharyngeal cancer and occupational exposure to asbestos and man-made vitreous fibers: results of a case-control study.

BACKGROUND: The data from a case-control study performed in France between 1989 and 1991 were used to test whether exposure to either asbestos or to man-made vitreous fibers (MMVF) is a risk factor for cancer of the larynx or the hypopharynx. METHODS: This study involved 315 incident cases of laryngeal cancer, 206 cases of hypopharyngeal cancer, and 305 hospital-based controls with other types of cancer, all recruited in 15 hospitals in six French cities. The subjects' past occupational exposure to asbestos and to four types of MMVF (mineral wool, refractory ceramic fibers, glass filaments, and microfibers) was evaluated based on their job history, with the aid of a job-exposure matrix. Odds ratios were calculated with unconditional logistic regression, with adjustment for smoking and drinking levels. RESULTS: Exposure to asbestos resulted in a significant increase in the risk of hypopharyngeal cancer (OR = 1.80, 95% CI: 1.08-2.99) and a nonsignificant increase in the risk of laryngeal cancer (OR = 1.24, 95% CI: 0.83-1.90). Risk was highest for the epilarynx (highest cumulative level of exposure: OR = 2.22, 95% CI: 1.05-4.71). Exposure to mineral wools was of borderline significance for the risk of hypopharyngeal cancer (OR = 1.55, 95% CI: 0.99-2.41), and nonsignificantly associated with the risk of laryngeal cancer (OR-1.33, 95% CI: 0.91-1.95). The risk was again highest for the epilarynx (OR = 1.85, 95% CI: 1.08-3.17). No significant results were observed for the other MMVF. CONCLUSIONS: These results suggest that asbestos exposure increases the risk of epilaryngeal and hypopharyngeal cancers. It is difficult to reach a conclusion about the effects of mineral wools, because nearly all the exposed subjects were also exposed to asbestos. The possible effects of other MMVF were difficult to assess in this study, because of the paucity of exposed subjects.

Adult↗

PubMed1988

Railroad workers with pleural plaques: I. Spirometric and nitrogen washout investigation on smoking and nonsmoking asbestos-exposed workers.

Eighty-seven workers exposed to asbestos in a railroad car repair shop, with characteristic asbestos-induced pleural plaques, underwent extensive lung-function examination. Vital capacity (VC) showed the greatest reduction among the static lung volumes, with an asymmetrical distribution of one-fourth of the subjects below 80% of the predicted value. Logistic regression demonstrated VC to be sufficient for optimal discrimination of asbestos-exposed subjects from a group of matched controls. No further discriminatory power was gained by additional spirometric measures, lung mechanics, blood gas analysis, or diffusing capacity. Smoking had an influence on dynamic but not on static lung volumes. In conclusion, reduced static lung volumes among smoking asbestos-exposed workers with pleural plaques should, in the absence of other lung diseases, be mainly attributed to the asbestos exposure.

Adult↗

PubMed1983

Immunologic aberrations in asbestos cement workers: dissociation from asbestosis.

Immunoregulatory disorders have been implicated in the pathogenesis of asbestosis. We therefore compared the immunologic status of a well-characterized group of 31 current and former asbestos-cement workers with that of a group of 52 healthy controls, after adjustments had been made for the possible confounding effects of age, race, and smoking. The asbestos workers had significantly decreased percentages and numbers of both B and T lymphocytes in peripheral blood and a paradoxical IgG hypergammaglobulinemia. Analysis of T-lymphocyte subpopulations revealed that total T-cell numbers (OKT3+), helper-inducer T-cell numbers (OKT4+), and suppressor-cytotoxic T cell numbers (OKT8+) were decreased by similar proportions. These decreases were negatively correlated with time elapsing since the end of exposure to asbestos. In both workers and controls, lymphocyte proliferative responses to phytohemagglutinin (PHA) were correlated positively with the number of OKT4+ cells and negatively with age and serum IgG levels. When adjustments had been made for these confounding variables, no differences in PHA responses were noted between workers and controls. No relationship was detected in the workers between any of the immunologic aberrations noted and (1) radiographic category of pneumoconiosis, (2) estimates of cumulative asbestos exposure, or (3) abnormalities of pulmonary function. These data suggest that the immunologic perturbations we have noted in asbestos-exposed individuals are epiphenomena, unrelated to the pathogenesis of asbestosis itself.

Adult↗

PubMed1987

Asbestos fibres introduce trace metals into streamwater and sediments.

Based on a case study in the Sumas River, it is demonstrated that asbestos fibres, which were introduced by a massive landslide, have altered the water quality and sediment conditions in the downstream section of the river. Asbestos fibres, because of their small size, are readily transported and resuspended i in stream systems. Associated with the fibres are high quantities of Ni, Cr, Co and Mn which occur as contaminations and isomorphic substitutions in most asbestos materials. A direct link between discharge, asbestos fibre and Ni concentrations was demonstrated in the water. Trace metal values in the sediments decrease with distance from the point source but the concentrations 20 km downstream of the slide are still significantly higher than levels at a control station unaffected by the slide. Asbestos fibres leach in acid media, and Mg and trace metals are removed. The process and rates were illustrated on the basis of laboratory experiments using organic acids. Since the pH in the streamwater is decreasing from 8.4 to 7.1 in the downstream direction, trace metals release is of concern.

Journal Article↗

PubMed1991

Monitoring the presence of asbestos in a residential apartment building.

Asbestos was once frequently used in building materials, but airborne fibres are now associated with serious health risks. This paper discusses the properties of asbestos and the ways in which certain forms can cause disease. Risks to the health of residents of asbestos-containing building are also explored. The detection, measurement and control of airborne asbestos demands careful monitoring. A case study is presented which describes the various procedures used to investigate the potential risks to residents of an asbestos-containing apartment building. Based on this investigation, recommendations are outlined for precautionary measures, mitigation techniques and further monitoring.

Journal Article↗

PubMed1988

Impairments in functional subsets of T-suppressor (CD8) lymphocytes, monocytes, and natural killer cells among asbestos-exposed workers.

Peripheral blood leukocytes from asbestos-exposed workers were analyzed by dual color flow cytometry using monoclonal antibodies that identify developmental (HLA-DR) and functional (Leu 8) subsets of T helper, suppressor lymphocytes, and monocytes. An increase in the number of T suppressor cells was closely associated with a decrease in T lymphocyte functions while numerical defects in activated monocytes (Leu M3+Ia+) and natural killer cells (Leu 7+) were correlated with a depressed Th/Ts ratio. Furthermore, among asbestos-exposed workers with depressed T cell functions we have demonstrated a significantly higher number of the effector Ts (Leu 2+ Leu 8-) subset which regulates both the Th/Ts lymphocyte system as well as B cells and NK cell activities. These findings identified changes in the T suppressor feedback regulatory loop as being responsible for the immunoregulatory imbalance among long-term asbestos workers. In double blind analyses of demographic and radiographic data these phenotypic changes were not correlated with age, smoking history, or duration of exposure but were associated with radiographic evidence of asbestos-associated effects. This correlation established a direct link between asbestos exposure and the subsequent development of immune dysfunction.

Adult↗

PubMed1982

Effects of cigarette smoking on pulmonary function in asymptomatic asbestos workers with normal chest radiograms.

A comprehensive health screening program consisting of standardized health and occupational history questionnaire, blood chemistry profile, complete blood count, urinalysis, chest radiograph, and pulmonary function testing was organized for the Asbestos Workers Union Local Number 1 in St. Louis, Missouri. The program was available on a voluntary basis to all the workers in the Union. One hundred and thirty-five male caucasian workers or 44% of the membership volunteered to participate and all the data were used in this study. All blood chemistry profiles and urinalysis results were within normal limits. Twenty-two of the asbestos workers had radiologic pulmonary abnormalities as well as severe pulmonary function impairment. The remaining 113 workers were divided into subgroups based on the number of years of exposure to asbestos and their smoking history. Although asymptomatic, workers with more than 20 years exposure to asbestos had significantly decreased pulmonary functions compared to those with less than 20 years exposure. When smokers and nonsmokers were compared, an additive effect between smoking and asbestosis was observed. This study also discovered that significant decreases in pulmonary functions occur early in the exposure to asbestos.

Adult↗

PubMed1991

Mesotheliomas due to asbestos used in railroads in Italy.

The available knowledge of the oncogenic risks of asbestos, the presentation of some data on the uses of asbestos in railroads, with particular regard to the Italian State Railroads (Ferrovie dello Stato = FS), and the identification of groups at risk because of exposure to asbestos used in railroads are briefly reviewed. The available data in the literature on the pathologic effects of such exposure, and in particular on the onset of mesotheliomas among machinists and other railroad workers, are also summarized. Eighty-three cases, in various Italian regions, of mesothelioma (78 pleural, 4, peritoneal, and 1 pericardial) are reported that are related to the exposure to asbestos used in railroads. Twenty-six of these cases (among which 25 were reported in the Emilia-Romagna region) were submitted to a detailed study at the Bologna Institute of Oncology. Forty-nine cases of mesothelioma occurred among FS workers, in particular machinists; 29 cases occurred among machinists of rolling-stock workshops not belonging to the FS; 3 cases occurred among travelling workers of rolling-stock not belonging to the FS; 2 cases were found in members of the family (a daughter and a wife) of FS workers. This series of cases, together with similar data from the literature, proves the existence and gravity of an actual health risk due to asbestos used in the railroads. On the basis of the available data, the following steps are considered necessary: the adoption of preventive measures, the performance of medical oncological surveillance, the promotion of systematic epidemiologic investigations, and, finally, the placement of greater emphasis on basic research, aimed at generating information on the biological events taking place during the incubation period of the tumors. This information, hopefully, could be used to reduce the biological effect of exposure, and therefore for controlling the neoplastic process before onset of the disease in those who, having been exposed, although healthy, are potentially at risk.

Epidemiologic Methods↗

PubMed1987

Non-malignant asbestos diseases in workers in an electrochemical plant.

The prevalence of non-malignant asbestos related disorders was studied in a group of men who had been subjected to different levels of asbestos exposure when working at an electrochemical plant producing nitric acid sometime between 1928 and 1970. There were 153 men eligible for an initial clinical examination in 1979-80 and that group has been followed up to 1985. Among the cohort members the "accumulated prevalence" of lung fibrosis alone or in combination with pleural plaques and of "pleural plaques only" was 24.2% and 24.8% respectively. The subgroup with the heaviest exposure had a total prevalence of asbestos related disorders of 82.5%. Only study subjects with lung fibrosis had statistically significant increased prevalences of respiratory symptoms. All subgroups from the study population, however, had mean spirometric values under the age, height, and smoking specific predicted means. Subjects with heavy asbestos exposure and current smoking had a prevalence of three or more respiratory symptoms of 28.8% compared with 5.6% among lightly exposed never smokers. Pleural crepitations at chest auscultation were more prevalent among subjects with radiologically visible asbestos related disorders than among study subjects with normal chest x ray films. During the follow up from 1980 to 1985, three cases of lung cancer, two of pleural malignant mesothelioma, and one of stomach cancer were found among the cohort members.

Adult↗

PubMed1989

Role of computed tomography in evaluating asbestos related lung disease.

To find how computed tomography (CT) may be effectively used in individuals with suspected asbestos related lung disease 30 men with a history of exposure to asbestos were studied. All subjects underwent high kilovoltage posteroanterior and left lateral chest radiographs and chest CT. Eighteen were randomly selected asbestos workers referred for routine surveillance. The remaining 12 were patients who had been referred for investigation of respiratory symptoms or abnormal routine chest radiograph, or both, and found to have chest radiographic changes compatible with asbestos related lung disease. In the group referred for routine surveillance both pleural shadowing and pulmonary shadowing were shown on CT but not chest radiographs in only one case. Five were thought to have pleural shadowing on chest radiographs but this was confirmed on CT in only one case. All 12 patients referred for investigation showed pleural shadowing on chest radiographs; this was confirmed in all cases on CT which also showed unsuspected pulmonary shadowing in five cases. These findings suggest that it is not appropriate to use chest CT routinely in all asbestos workers referred for routine surveillance. When CT is used selectively in those with pleural shadowing on plain chest radiography, however, it is helpful in refuting or confirming the presence of pleural disease and may show unsuspected pulmonary shadowing.

Adolescent↗

PubMed1991

Asbestosis as a precursor of asbestos related lung cancer: results of a prospective mortality study.

A prospective mortality study of 839 men employed in the manufacture of asbestos cement products in 1969 examined lung cancer risk in relation to lung fibrosis seen on chest x ray film, controlling for age, smoking, and exposure to asbestos. Twenty or more years after hire, no excess of lung cancer was found among workers without radiographically detectable lung fibrosis, even among long term workers (greater than or equal to 21.5 years); nor was there a trend in risk by level of cumulative exposure to asbestos among such workers. By contrast, employees with small opacities (greater than or equal to 1/0; ILO classification) experienced a significantly raised risk of lung cancer (nine observed deaths v 2.1 expected), even though their exposures to asbestos were similar to the exposures of long term workers without opacities. In this population, excess risk of lung cancer was restricted to workers with x ray film evidence of asbestosis, a finding consistent with the view that asbestos is a lung carcinogen because of its fibrogenicity.

Adult↗

PubMed2000

High-resolution computed tomography in cases with environmental exposure to asbestos in Turkey.

BACKGROUND AND OBJECTIVES: Although all parts of the lung can be affected as a consequence of asbestos exposure, most CT protocols tend to scan only the middle and lower parts of the thorax. The aim of this study was to investigate parenchymal and pleural lesions of persons exposed to environmental asbestos, using a high-resolution computed tomography (HRCT) protocol scanning the whole thorax. METHODS: We analyzed the chest radiographs and HRCT scans of 26 patients who presented bilaterally with multiple pleural plaques related to environmental asbestos exposure. RESULTS: Twenty-four cases (92%) had an abnormal HRCT suggestive of asbestosis. Apart from common HRCT changes related to asbestosis, we detected apical pleural thickening (APT) in 9 cases as well as a coarse honeycomb pattern adjacent to APT in 7 of these cases. Cavitary lesions due to pulmonary tuberculosis were observed on HRCT scans from 4 patients in total. Neither apical pulmonary fibrosis nor cavitary lesions were visible on chest radiographs. CONCLUSIONS: We suggest that the HRCT protocol for examining asbestos-exposed individuals with pleural plaques on chest X-rays should include the whole thorax, since the asbestos-related pathologies may involve all parts of the lung.

Adult↗