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Cancer due to asbestos exposure.

To determine the relationship between malignancies and asbestos exposure, the number of asbestos bodies in wet lung tissue was counted by light microscopy according to the modified method of Smith and Naylor, and occupational histories were examined. The results revealed that 17 (89 percent) of 19 malignant mesotheliomas, 39 (38 percent) of 104 lung cancers, 23 (37 percent) of 62 gastric cancers, and 13 (28 percent) of 45 colon cancers were shown to be cases with asbestos exposure. These values were significantly higher than those of noncancerous cases (200 cases). It is of interest that five out of ten cases of leukemia were related to asbestos exposure. Nearly all multiple cancers including lung and gastric cancer in this study were also cases with asbestos exposure. Additional research should be conducted on the carcinogenicity of asbestos for multiple cancers.

Acute Disease↗

Numbers of asbestos bodies in urban patients with lung cancer and gastrointestinal cancer and in matched controls.

We compared the numbers of asbestos bodies extracted from the lungs of 103 patients with lung cancer and 50 patients with gastrointestinal malignant neoplasms to the numbers of bodies extracted from lungs of control patients matched for age, sex, smoking habits, and, in some cases, occupation. All patients were urban dwellers over the age of 40 years, and none was a primary asbestos worker. No differences in the counts of asbestos bodies were observed between the tested and control populations. The numbers of asbestos bodies did correlate well with occupation; the highest counts were found in male manual laborers. We conclude that in the urban population studied herein, the numbers of asbestos bodies alone do not correlate with the presence of pulmonary or gastrointestinal carcinoma; however, uncoated asbestos fibers are also known to be present in the lung, and the possibility that such tumors may be related to the numbers of these fibers in lungs remains to be explored.

Adult↗

Relationship between number of asbestos bodies in autopsy lung and pleural plaques on chest X-ray film.

We investigated the relationship between number of asbestos bodies and pleural plaques. Using sodium hypochrolite, we examined 400 autopsy lungs and could detect 71 cases whose asbestos bodies were significantly high. We checked pleural plaques on chest x-ray films of these 71 cases and compared the exact plaque at autopsy. By the criteria of Askergren and Szamosi, we classified these into three groups (probable, definite, definite with calcification). This classification is consistent with the pleural plaques found at autopsy. Cases whose pleural plaques were definite (thick) had many more asbestos bodies than indefinite cases. As for occupational histories, there were 23 cases who worked in Japanese Naval shipyards before and during World War II, 14 others in various shipyards, and 14 others who also had a history of asbestos exposure. These 51 patients died more than 30 years after the first asbestos exposure. Twenty had no definite asbestos exposure.

Adult↗

Pleural mesothelioma and household asbestos exposure.

This article discusses the development of asbestos-induced malignant mesotheliomas after non-occupational environmental exposure to asbestos through contact with occupationally exposed household members. In our policlinic, we have seen six fatal pleural mesothelioma cases (five wives and one son of asbestos-industry workers) with no history of occupational asbestos exposure. In five women, a causal relation was established between the fatal disease and inhalation of asbestos fibers while cleaning the contaminated work-clothes and shoes of their husbands at home. The son had also been exposed to asbestos throughout his childhood during daily visits with his father at the workplace.

Adult↗

Asbestos toxicity: an immunologic perspective.

Asbestos has long been associated with a number of life threatening pulmonary diseases, including asbestosis and mesothelioma. While the lung is the primary target organ for asbestos toxicity, a number of clinical and experimental studies over the past 30 years have shown that the immune system may also be altered by exposure to asbestos at occupationally relevant concentrations. Whereas early clinical studies generally focused on systemic observations of immune alteration, more recent studies have assessed the immunological changes occurring in the lung, the primary target organ of asbestos. This review will focus on the investigations that examine the influence of asbestos on systemic and local immunity, as well as the role that the immune system may play in asbestos-related disease.

Antibody Formation↗

Impact of acute and subchronic asbestos exposure on some parameters of antioxidant defense system and lung tissue injury.

Asbestos fibers have been used in industry for decades. Deleterious effect of asbestos on the lungs has been documented. However, the mechanism of asbestos related diseases has not been fully explained yet. Numerous papers suggest there is a role of reactive oxygen intermediates (ROI) in asbestos-induced lung disease development. The excess ROI produced can be removed from the lungs by enzymatic and nonenzymatic antioxidants. The aim of our study was to compare the levels of antioxidants (ascorbic acid, retinol, alpha-tocopherol, glutathionperoxidase) as well as some markers of lung injury (lipid peroxides, total amount of protein, alkaline phosphatase) in asbestos treated Wistar-rats both 24 hr and 3 months after exposure to those in the controls, and to find out if the changes in antioxidant levels could affect impairment of the lungs. Decreased levels of antioxidants and increased values of lung tissue injury parameters in exposed groups suggest involvement of ROI in the mechanism of asbestos lung disease development, resulting in lung tissue injury, both 24 hr and 3 months after exposure.

Analysis of Variance↗

Asbestos exposure in malignant mesothelioma of the pleura: a survey of 557 cases.

A series of 557 malignant mesotheliomas of the pleura diagnosed in the Trieste-Monfalcone area, Italy, in the period 1968-2000 were reviewed. The series included 492 men and 65 women, aged between 32 and 93 years (median age 69 years). Necropsy findings were available in 456 cases (82%). Occupational histories were obtained from the patients themselves or from their relatives by personal or telephone interviews. Routine lung sections were examined for asbestos bodies in 442 cases. In 109 cases isolation and counting of asbestos bodies were performed. A majority of people had histories of working in the shipyards. Asbestos bodies were observed in lung sections in 67% of the cases. Lung asbestos body burdens after isolation ranged between 20 bodies and about 10 millions of bodies/g dried tissue. Latency periods (time intervals between first exposure to asbestos and death) ranged between 14 and 75 years (mean 48.8 years, median 51.0). Latency periods among insulators and dock workers were shorter than among the other categories. High asbestos consumption occurred in many countries in the 1960s and in the 1970s. The data on latency periods obtained in the present study suggest that a world mesothelioma epidemic has to be expected in the coming decades.

Adult↗

Reaction of rat lungs to inhaled chrysotile asbestos following acute and subchronic exposures.

Inhalation of asbestos fibers can cause fibrotic and neoplastic diseases in the lung. The early in vivo interactions between fibers and lung tissue that initiate these diseases have received little study. Male and female Fischer 344 rats were placed in inhalation chambers and exposed to 9.06 +/- 1.83 mg/m3 (average respirable mass) of chrysotile asbestos for 1 hr, 1 day, 7 hr/day for 5 days, or 5 days/week for 3 months. Qualitative examination of the tissue showed that, after 1 day, fibers were found not only in the alveolar macrophages, but also in the epithelium and interstitium of the alveolar region. After 3 months, numerous fibers were present in the epithelium and interstitium. Morphometric analysis of this tissue showed that these compartments were also the most significantly changed as a result of asbestos exposure. The majority of epithelial changes were attributable to a 57% increase in the number of type II cells and a 90% increase in their average cell volume. The interstitial cell population increased 58% with a 40% increase in the average cell volume. There was no significant increase in the volume of noncellular interstitium. A morphologic characterization of the interstitial cells showed that interstitial macrophages accounted for almost the entire increase in this population and that 88% of the fiber-containing cells were macrophages. Several interstitial macrophages contained membrane-bound inclusions which were shown by x-ray energy spectrometry to be microcalcifications. They were composed of rings of calcium phosphate granules around asbestos fibers. These microcalcifications may indicate sublethal cell injury caused by the presence of asbestos fibers in the cell cytoplasm. Fibers which enter but do not kil alveolar cells may be an essential component for the pathogenesis of lung disease caused by asbestos inhalation.

Animals↗

Analysis of asbestos fiber burden in lung tissue from mesothelioma patients.

Mesothelioma is a rare neoplasm that occurs most frequently in individuals with previous asbestos exposure. Differences for risk of development of asbestos-related mesothelioma and lung cancer have been attributed to the various types of asbestos, as well as to the dimension of the inhaled fibers. In the present study, 55 individuals with the pathological diagnosis of mesothelioma were evaluated as to ferruginous body and fiber content in lung tissue. The procedures used in the analysis included tissue digestion and analysis of the collected material for ferruginous bodies by light microscopy and for uncoated fibers by analytical transmission electron microscopy. Forty-six of the samples had ferruginous body concentrations of over 1000/per gram dry weight of lung tissue. The majority of the cores of these ferruginous bodies were amosite. Likewise, the most common uncoated asbestos fiber in the tissue was amosite. Only a small percentage of each type of asbestos would have been visible by light microscopy or even potentially by electron microscopy if the magnification was not sufficient to detect those with thin (< 0.2 micron) diameters. The consistent finding in most of the cases was a considerable presence of asbestos, often of mixed types.

Adult↗

Malignant mesotheliomas in Kure City, Japan: the relationship of asbestos exposure.

Eighteen patients with malignant mesothelioma were seen at Kure Mutual Aid Hospital over a 10-year period. According to occupational history, chest x-ray manifestations, and evidence of asbestos bodies in the tissue, 13 of these cases were definitely thought to be due to exposure to asbestos as a result of two or three of these items testing positive. Kure City is one of the major ship-building cities in Japan since the 1920s. Most of the 18 patients worked in ship building before and during World War II. Malignant mesothelioma appeared about 40 years after their first exposure to asbestos. In western countries, most malignant mesotheliomas are thought to be induced by exposure to asbestos fibers (1,2). Consequently, there has been a serious effort to deal with this problem recently, including lowering rate of exposure. In Japan, however, there have been few reports that asbestos fibers caused malignant mesothelioma (3). This report suggests that an increased incidence of malignant mesotheliomas in a specific area of Japan may also be due to exposure to asbestos fibers.

Adult↗

Environmental exposure to asbestos in eastern Turkey.

In this study, the authors investigated the prevalence of asbestos-related disorders among the inhabitants of Güzelyurt, a town in Malatya, located in eastern Turkey. The authors examined river bed, white soil, and stucco samples taken from various locales in Güzelyurt, and they confirmed the presence of tremolite and chrysotile asbestos fibers. Subjects (N = 920; 449 males and 471 females) were examined by photofluoroscopy. Eighty-five patients (9.2%) had asbestos-related radiological findings; risk increased with age. Calcified pleural plaques were seen more frequently in individuals > or = 50 yr of age, compared with younger subjects (p < 0.01). Asbestos-related disorders were prevalent in the inhabitants of Güzelyurt, the population of which is exposed environmentally to asbestos--primarily the result of the stuccoing and whitewashing of houses with soil that contains asbestos.

Adolescent↗

Evaluation of serum aminoterminal propeptide of type III procollagen as an early marker of the active fibrotic process in asbestos-exposed workers.

In an evaluation of the possibility of type III procollagen N-terminal propeptide (PIIINP) being an early marker of the active fibrotic process in asbestos-exposed workers, 91 asbestos workers had higher serum PIIINP concentrations than 108 referents. In 24 workers exposed to low levels of airborne asbestos, the serum PIIINP was higher than in the referents but lower than in an exposed group with higher exposure; furthermore a significant correlation (r = 0.63) was found between serum PIIINP and individual cumulative exposure. These data suggest a dose-effect relationship between asbestos exposure and PIIINP serum concentration. In addition workers with a reduced pulmonary function had higher PIIINP values than the referents or the exposed workers with normal pulmonary function. The serum PIIINP levels were related to asbestos exposure even at low airborne concentrations and may represent an early biological marker of impending fibrotic process induced by asbestos.

Adult↗

Incidence of cancer among the participants of the Finnish Asbestos Screening Campaign.

OBJECTIVES: Cancer risk has been estimated for asbestos production workers or other heavily exposed asbestos workers in numerous studies. The bulk of the asbestos epidemic results come, however, from past intermittent exposures during asbestos product use. This study concentrated on estimating the risk of cancer in such a population. METHODS: Altogether 23285 men and 930 women invited to a nationwide screening campaign for benign asbestos-related diseases in 1990-1992 were followed for cancer through the Finnish Cancer Register up to 1998. Standardized incidence ratios (SIR) were calculated in comparison with the total Finnish population. RESULTS: Altogether 1392 cases of cancer were found among the men. The risk was slightly, but significantly elevated for lung cancer [SIR 1.14, 95% confidence interval (95% CI) 1.01-1.26), mesothelioma (SIR 2.77, 95% CI 1.66-4.31), and prostate cancer (SIR 1.21, 95% CI 1.09-1.34). The risk of lung cancer was slightly higher among the invited nonparticipants (SIR 1.48, 95% CI 1.20-1.79) than among the participants (SIR 1.02, 95% CI 0.88-1.17). About 98% of the lung cancers occurred in current or ex-smokers. CONCLUSIONS: In a population of long-term construction workers, the risk of lung cancer and mesothelioma was increased, but considerably lower than among insulators, asbestos sprayers, or patients with asbestosis. As it was not possible to follow most of the invited nonparticipants in the original screening study, selection bias by smoking or other life-style factors possibly correlated to the individual's decision to participate in the health screening cannot be excluded.

Asbestos↗

[Medical impact of screening of benign pleural lesions associated with the inhalation of asbestos dust].

Asbestos-related benign pleural lesions can involve the parietal pleura (pleural plaques), and/or visceral pleura as focal or diffuse (diffuse pleural thickening) fibrosis. Benign asbestos pleurisy and rounded atelectasis are linked with visceral pachypleuritis, the former as a cause, the latter as a consequence. The prevalence of these lesions, particularly pleural plaques, is very high, reaching 25% in populations of workers exposed intermittently to asbestos. Conventional radiology has a sensitivity less than 50% for detection of plaques, and a specificity less than 85%. Tomodensitometry is today the reference diagnostic tool: availability, cost and irradiation have to be considered before its use in mass screening. Pleural plaques are most often asymptomatic and a functional impairment cannot be proven usually on an individual basis. Visceral pleural thickening is more often accompanied by symptoms (dyspnea, pain) and functional impairment. There is no treatment susceptible to produce a regression of pleural lesions. Asbestos exposure increases the risk of pulmonary and pleural cancers. However there is no evidence of an increased risk in subjects with plaques compared with subjects without plaques but an equivalent asbestos exposure. The cost and the risk of diagnostic procedures induced by the screening, as well as the anxiety provoked by the detection of radiologic abnormalities are to be considered. Finally it is difficult today to justify the screening of benign pleural lesions by arguing an improvement of the life expectancy or of the quality of life of former asbestos exposed workers. It is probable that benefit of a screening will be of a social type, at an individual or a collective level.

Air Pollution↗

Asbestos worker protection. Environmental Protection Agency (EPA). Final rule.

In this Final Rule, EPA is amending both the Asbestos Worker Protection Rule (WPR) and the Asbestos-in-Schools Rule. The WPR amendment protects State and local government employees from the health risks of exposure to asbestos to the same extent as private sector workers by adopting for these employees the Asbestos Standards of the Occupational Safety and Health Administration (OSHA). The WPR's coverage is extended to State and local government employees who are performing construction work, custodial work, and automotive brake and clutch repair work. This final rule cross-references the OSHA Asbestos Standards for Construction and for General Industry, so that future amendments to these OSHA standards are directly and equally effective for employees covered by the WPR. EPA also amends the Asbestos-in-Schools Rule to provide coverage under the WPR for employees of public local education agencies who perform operations, maintenance, and repair activities. EPA is issuing this final rule under section 6 of the Toxic Substances Control Act (TSCA).

Asbestos↗

[Clinical evaluation of rounded atelectasis induced by exposure to asbestos].

We encountered 15 patients with rounded atelectasis induced by exposure to asbestos from 1992 to 1999. All patients were men whose ages ranged from 42 to 85 years, with a mean age of 64.2 +/- 11.5 years. Rounded atelectasis was present only in the right lung and two patients had 2 rounded atelectasis in the right lung. In eight cases, the rounded atelectasis was found in segment 10, while in the others, it was found in segments 4, 5, 6, 8, and 9. Although evidence of symptoms was absent, rounded atelectasis was detected in six patients through medical examinations. Others complained of chest pain and dyspnea. Thirteen patients displayed pleural plaques and only 2 patients revealed asbestosis. Malignant complications were discovered in 4 patients, of whom 3 showed primary lung cancer and 1 suffered acute myelocytic leukemia. In their occupational histories, 7 patients had been exposed to asbestos in the shipyards and 5 in the construction field. The mean period of the exposure was 25.1 +/- 12.7 years, and the latency period from the first asbestos exposure to the detection of atelectasis was 35.1 +/- 8.8 years. Five autopsied patients had more than 10,000 asbestos bodies in the lung, which indicated heavy exposure to asbestos. These results suggest that rounded atelectasis may appear after high-dose exposure to asbestos.

Adult↗

A mutant epidermal growth factor receptor targeted to lung epithelium inhibits asbestos-induced proliferation and proto-oncogene expression.

Asbestos is a ubiquitous naturally occurring fiber causing multiple cancers and fibroproliferativedisease. The mechanisms of epithelial cell hyperplasia, a hallmark of the initiation of lung cancers by asbestos, have been unclear. We demonstrate here that mice expressing a dominant-negative mutant epidermal growth factor receptor (EGFR) under the control of the human lung surfactant protein-C promoter exhibit decreased pulmonary epithelial cell proliferation without alterations in asbestos-induced inflammation. In contrast to transgene-negative littermates, inhalation of asbestos by mice expressing the mutant EGFR does not result in early and elevated expression of early response proto-oncogenes (fos/jun or activator protein 1 family members). Additionally, quantitative reverse transcriptase-PCR analysis for levels of c-jun and c-fos in bronchiolar epithelium isolated by laser capture microdissection demonstrates increases in expression of these genes in asbestos-exposed epithelial cells. Results show that the EGFR mediates both asbestos-induced proto-oncogene expression and epithelial cell proliferation, providing a rationale for modification of its phosphorylation in preventive and therapeutic approaches to lung cancers and mesothelioma.

Administration, Inhalation↗

[Asbestos as an envoronmental carcinogen (author's transl)].

Relations between asbestosis and bronchial carcinoma and also since a long time for diffuse malignant pelural and peritoneal mesothelioma have been ascertained for professional exposure to asbestos. On the other hand such relations can be proved statistically for non-professional environmental influence only with malignant serosa tumors. Their increased occurrence goes parallel to the hyaline (calcified) pleura-plaques, to another professional and non-professional consequence of asbestos dust inhalations. There is not enough evidence to accuse asbestos to be a carcinogen causing also other malignomas. It is sure, the number of uncontrolled persons, occupationally or nonoccupationally exposed to asbestos, is still very high. Nevertheless no increased risk of cancer, provoked by asbestos can be supposed for the public at present. For selected population groups, however, increased occurence of mesothelioma cannot be denied, at least in the past. Favorable Favorable conditions exist for the solution of problems still unsolved in asbestosis control, due to the registration of all persons exposed to asbestos dust, and due to the commitment of notifying all tumors.

Asbestos↗