Lee HE, Kim HR.

Occupational Safety and Health Research Institute, KOSHA, Inchoen, Korea.

Abstract

Malignant mesothelioma and lung cancer are representative examples of occupational cancer. Lung cancer is the leading cause of cancer death, and the incidence of malignant mesothelioma is expected to increase sharply in the near future. Although information about lung carcinogen exposure is limited, it is estimated that the number of workers exposed to carcinogens has declined. The first official case of occupational cancer was malignant mesothelioma caused by asbestos exposure in the asbestos textile industry in 1992. Since then, compensation for occupational respiratory cancer has increased. The majority of compensated lung cancer was due to underlying pneumoconiosis. Other main causative agents of occupational lung cancer included asbestos, hexavalent chromium, and crystalline silica. Related jobs included welders, foundry workers, platers, plumbers, and vehicle maintenance workers. Compensated malignant mesotheliomas were associated with asbestos exposure. Epidemiologic studies conducted in Korea have indicated an elevated risk of lung cancer in pneumoconiosis patients, foundry workers, and asbestos textile workers. Occupational respiratory cancer has increased during the last 10 to 20 yr though carcinogen-exposed population has declined in the same period. More efforts to advance the systems for the investigation, prevention and management of occupational respiratory cancer are needed.

Méndez-Vargas MM, López-Rojas P, Campos-Pujal GA, Marín-Cotoñieto IA, Salinas-Tovar S, Fernández-Muñoz Mde J.

Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Distrito Federal, México. medmakika1915@yahoo.com.mx

Abstract

Objective: To identify the characteristics of pleural mesothelioma in patients exposed to asbestos.

Methods: A transverse study in 3700 cases of lung cancer was conducted. There were identified 21 cases with mesothelioma. Age, gender, smoking history, cancer development, dissemination, cytohistochemistry, lethality and total lung capacity were studied. ANOVA test was used.

Results: The incidence was of 0.45/100,000 patients. Four (19%) corresponded to occupational exposure (OE), seven (33%) para-occupational (PE) and ten (48%) environmental (EE). The mean age at detection was 50 years for PE, 55 years for EE and 64 years for OE. Twenty cases were male. Thirteen patients (62%) were active cigarette smokers. The latency time in PE mesothelioma was 34.5 years, in OE 40 years, and in EE more than 40 years. In 19 (90%) cases the tumor was disseminated. Diagnosis was confirmed by cytohistochemistry. Malignant mesothelioma was reported in 19 (90%) cases. The survival period was 5 months for OE patients, 10 in PE and 16 in EE.

Conclusions: There is a low incidence of malignant mesothelioma in our population. Male was the predominant group. Occupational and paraoccupational exposure predominated in patients.

Moore AJ, Parker RJ, Wiggins J.

Department of Respiratory Medicine, Wexham Park Hospital, Wexham, Slough, Berkshire, UK. a.moore@ic.ac.uk

Abstract

Malignant mesothelioma is a fatal asbestos-associated malignancy originating from the lining cells (mesothelium) of the pleural and peritoneal cavities, as well as the pericardium and the tunica vaginalis. The exact prevalence is unknown but it is estimated that mesotheliomas represent less than 1% of all cancers. Its incidence is increasing, with an expected peak in the next 10-20 years. Pleural malignant mesothelioma is the most common form of mesothelioma. Typical presenting features are those of chest pain and dyspnoea. Breathlessness due to a pleural effusion without chest pain is reported in about 30% of patients. A chest wall mass, weight loss, sweating, abdominal pain and ascites (due to peritoneal involvement) are less common presentations. Mesothelioma is directly attributable to occupational asbestos exposure with a history of exposure in over 90% of cases. There is also evidence that mesothelioma may result from both para-occupational exposure and non-occupational “environmental” exposure. Idiopathic or spontaneous mesothelioma can also occur in the absence of any exposure to asbestos, with a spontaneous rate in humans of around one per million. A combination of accurate exposure history, along with examination radiology and pathology are essential to make the diagnosis. Distinguishing malignant from benign pleural disease can be challenging. The most helpful CT findings suggesting malignant pleural disease are 1) a circumferential pleural rind, 2) nodular pleural thickening, 3) pleural thickening of > 1 cm and 4) mediastinal pleural involvement. Involvement of a multidisciplinary team is recommended to ensure prompt and appropriate management, using a framework of radiotherapy, chemotherapy, surgery and symptom palliation with end of life care. Compensation issues must also be considered. Life expectancy in malignant mesothelioma is poor, with a median survival of about one year following diagnosis.

Park EK, Hannaford-Turner KM, Hyland RA, Johnson AR, Yates DH.

Research and Education Unit, Workers’ Compensation Dust Diseases Board of NSW, Sydney, Australia.

Abstract

Asbestos is a fibrous silicate which is recognized as causing a variety of lung disorders including malignant mesothelioma of the pleura, lung cancer and asbestosis. Asbestos use has been banned in most developed countries but exposure still occurs under strict regulation in occupational settings and also occasionally in domestic settings. Although the hazards of asbestos are well known in developed countries, awareness of its adverse health effects is less in other parts of the world, particularly when exposure occurs in non-occupational settings. Experience of asbestos use and its adverse heath effects in developed countries such as Australia have resulted in development of expertise in the diagnosis and treatment of asbestos-related diseases as well as in screening and this can be used to help developing countries facing the issue of asbestos exposure.

Keywords: Asbestos, Mesothelioma, Asbestos-related diseases, Occupational exposure, Public health

Pairon JC, Andujar P, Matrat M, Ameille J.

INSERM Unité 841, Créteil, France. JC.Pairon@chicreteil.fr

Abstract

Lung cancer and pleural mesothelioma are the most common occupational cancers.

Recent epidemiological studies have estimated that the fraction attributable to occupational factors varies from 13 to 29% for lung cancer in men and is about 85% for pleural mesothelioma in men. Previous occupational exposure to asbestos is the most common occupational exposure in these cancers. Mesothelioma immediately leads the clinician to look for past asbestos exposure. In contrast, the search for an occupational exposure that should be routine in all cases of lung cancer, is generally more difficult because of the number of occupational aetiological factors and the absence of criteria that allow distinction of an occupational cancer from a tobacco related one.

Therefore attention should be paid to the identification of occupational exposure in order to set up primary prevention programmes to prevent exposure still present in the working environment and, on the other hand, to identify the subjects entitled to the acknowledgement of occupational disease and/or to obtain the compensation available to asbestos victims.

Keywords: Asbestos, Silicon dioxide, Occupational diseases, Lung, Carcinogens

Schneider F, Sporn TA, Roggli VL.

Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, USA. frank.schneider@duke.edu

Abstract

This study reports changes in the frequency of detection of various asbestos fiber types between 1982 and 2005. Crocidolite is increasingly detected in U.S. mesothelioma patients. The percentage of crocidolite fibers detected in lung tissue has risen from 4 to 10%, and the percentage of cases in which crocidolite was detected increased from 19 to 37%. Meanwhile, the frequency of detection of amosite and chrysotile has decreased. The authors performed a detailed analysis of cases in which crocidolite was identified in the absence of amosite. Most of such cases were identified in recent years, a finding of concern since crocidolite is considered the most potent fiber type with respect to the pathogenesis of mesothelioma.

Keywords: amosite; amphiboles; asbestos; crocidolite; mesothelioma

Reid A, Heyworth J, de Klerk N, Musk AW.

Occupational Respiratory Epidemiology, School of Population Health, M431, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Alison.Reid@uwa.edu.au

Abstract

Objectives: Knowledge of mortality patterns following exposure to asbestos has been determined mostly from cohort studies of men who were exposed to asbestos in their workplace. Women are more likely to have obtained their asbestos exposure domestically or from their environment.

Methods: 2552 women and girls are documented to have lived in the blue asbestos mining and milling township of Wittenoom between 1943 and 1992 and were not involved in asbestos mining or milling. Quantitative asbestos exposure measurements were derived from periodic dust surveys undertaken in the industry and around the township. Death records were obtained for the period 1950–2004. Standardised mortality ratios (SMRs) were calculated to compare the Wittenoom women’s mortality with that of the Western Australian female population.

Results: There were 425 deaths, including 30 from malignant mesothelioma. There was excess mortality for all causes of death (SMR = 1.13), all neoplasms (SMR = 1.42), symptoms, signs and ill defined conditions (SMR = 6.35), lung cancer (SMR = 2.15) and pneumoconiosis (SMR = 11.8). Mortality from cancer of the ovary (SMR = 1.52), upper aerodigestive cancers (SMR = 2.70) and tuberculosis (SMR = 5.38) was increased but not significantly. The risk of death from mesothelioma was increased, but not significantly, in residents known to have lived with or washed the clothes of an Australian Blue Asbestos Company asbestos worker (HR = 2.67, 95% CI 0.77 to 9.21; HR = 2.61, 95% CI 0.85 to 7.99, respectively).

Conclusion: Women who were former residents of Wittenoom, exposed to asbestos in their environment or in their home, have excess cancer mortality, including mesothelioma, compared with the Western Australian female population.

Berry G, Pooley F, Gibbs A, Harris JM, McDonald JC.

School of Public Health, University of Sydney, Sydney, Australia. geoffb@health.usyd.edu.au

Abstract

A cohort of 1,154 employees, mainly women, who had worked 1940-1945 on the manufacture of military gas masks using filter pads containing 20% crocidolite, was traced through 2003, by which time 65 were known to have died from mesothelioma. The last known death with mesothelioma was in 1994, whereas a further 5 cases would have been expected in those with known duration of exposure. Lung tissue samples, from 50 deaths from mesothelioma and 20 other causes, had been analyzed for mineral fiber content. For ten of the mesothelioma cases data on fiber size were collected. Crocidolite fiber concentrations were analyzed in relation to exposure by time and duration. Fiber concentrations overall fell fairly steadily by decade of death, and increased with length of exposure up to 36 months and then fell sharply. The annual rate of elimination estimated by regression was 7.5% corresponding to a half life of 9.2 years. The proportion of fibers longer than 6 μm increased over time implying that the shorter fibers were eliminated more rapidly than the longer ones. The decline in concentrations with time confirms the hypothesis that crocidolite and, by inference, other amphibole fibers are slowly removed from the lung, but since the longer more carcinogenic fibers were cleared more slowly it is unclear to what extent this clearance explains the slowing down of the increase in mesothelioma mortality from about 40 years from the most recent exposure. The exact biostatistical models which most closely conform with the data remain open to question.

Sichletidis L, Chloros D, Spyratos D, Haidich AB, Fourkiotou I, Kakoura M, Patakas D.

Laboratory for the Study of Environmental Diseases, Pulmonary Clinic of Aristotle University of Thessaloniki, Thessaloniki, Greece.

Abstract

Background: Asbestos exposure is related to serious adverse health effects. However, there is disagreement about the relationship between chrysotile exposure and mesothelioma or lung cancer.

Objectives: Our aim was to investigate the mortality rate among workers exposed to relatively pure chrysotile in an asbestos cement factory.

Patients and Methods: In an asbestos cement plant opened in 1968, we prospectively studied all 317 workers. A quantity of 2,000 tons of chrysotile, with minimal amphibole contamination, was used annually until 1 January 2005. Asbestos fiber concentration was measured regularly. Date and cause of death were recorded among active and retired workers.

Results: Asbestos fiber concentration was always below permissible levels. Fifty-two workers died during the study. The cause was cancer in 28 subjects; lung cancer was diagnosed in 16 of them. No case of mesothelioma was reported. Death was attributed to cardiovascular diseases in 23 subjects and to liver cirrhosis
in 1. Overall mortality rate was significantly lower than that of the Greek general population, standardized mortality ratio (SMR) was 0.71 (95% CI 0.53-0.93). Mortality due to cancer was increased (SMR 1.15, 95% CI 0.77-1.67), mainly due to lung cancer mortality (SMR 1.71, 95% CI 0.98-2.78), but not significantly.

Conclusions: Occupational exposure to relatively pure chrysotile within permissible levels was not associated with a significant increase in lung cancer or with mesothelioma. Decreased overall mortality of workers indicates a healthy worker effect, which – together with the relatively small cohort size – could have prevented small risks to be detected.

Keywords: Asbestos, Epidemiology, Lung cancer, Mesothelioma, Chrysotile

Betti M, Neri M, Ferrante D, Landi S, Biava A, Gemignani F, Bertolotti M, Mirabelli D, Padoan M, Ugolini D, Botta M, Bonassi S, Magnani C, Dianzani I.

Department of Medical Sciences, University of Piemonte Orientale, Via Solaroli 17, 28100 Novara, Italy.

Abstract

Malignant mesothelioma (MM) is a rare and aggressive tumor of the pleura. The most important causal factor for the development of MM is occupational exposure to asbestos. Different lines of evidence suggest a role of genetic background in MM development, as for other cancers. Two published studies observed an association between MM and N-acetyl-transferase 2 (NAT2) polymorphisms. First, a Finnish study observed that the NAT2 slow acetylator phenotype was associated with an increased risk of MM. Conversely, MM risk was higher in Italian subjects carrying the NAT2 fast acetylator genotypes. The conflicting results obtained in Finland and Italy could be ascribed to random chance, considering the small panel of patients and controls in the two studies, but also ethnic or other differences may have been important. To ascertain the role of NAT2 genotype, we performed a study on 252 MM patients and 262 controls recruited in two Northern Italy areas that were characterized by high asbestos exposure, due to intense industrial activities (an asbestos cement factory in Casale Monferrato, mainly shipyards and refineries in Liguria). Unconditional multivariate logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). NAT2 fast acetylator genotypes showed an increased OR, although not statistically significant, both in asbestos-exposed subjects (OR=1.47; 95% CI=0.96–2.26) and in the entire population (OR=1.38; 95% CI=0.93–2.04). These results suggest that NAT2 polymorphisms do not exert a strong effect on individual susceptibility to MM.

Keywords: Asbestos; Mesothelioma; N-acetyltransferase; Oxidative stress; Single nucleotide polymorphism