Apoptosis ; drug effects ; Asbestos ; toxicity ; Humans ; Mineral Fibers ; toxicity

Asbestos ; toxicity ; Humans ; Occupational Exposure ; adverse effects ; Pulmonary Alveolar Proteinosis

OBJECTIVETo study the cytotoxicity induced by chrysotile asbestos (CA), rock wool (RW) and wollastonite (WS).

METHODSV79 cells were divided into 4 groups. i.e. CA group, WS group, RW group and control group (200 microl PBS). The exposure concentration of dusts was 100 mg/L, The cell viability was detected by MTT and lactate dehydrogenase (LDH) activity assays. The technique of scanning electron microscopy was used to examine the change of V79 cells.

RESULTSSiO2 was main constituent for 3 kinds of dusts. In MTT assay, the cell viability of RW and WS groups was 64.8% and 65.7%, respectively, which were significantly higher than that (54.5%) of CA group (P < 0.01). In LDH assay, the LDH activity of RW and WS groups [(15.7 +/- 50.9), (12.3 +/- 3.7) U/L, respectively] was significantly lower than that [(20.2 +/- 0.9) U/L] of CA group (P < 0.05). In scanning electron microscopy examination, it was found that the two ends of V79 cells in CA group contained a great deal of fibers remaining bodies, but the V79 cell appearance in RW and WS groups was normal.

CONCLUSIONThe cytotoxicity induced by RW and WS is significantly lower than that induced by CA for V79 cell.

Animals ; Asbestos, Serpentine ; toxicity ; Calcium Compounds ; toxicity ; Cell Line ; drug effects ; Cricetinae ; Cytotoxins ; toxicity ; Lactate Dehydrogenases ; metabolism ; Mineral Fibers ; toxicity ; Silicates ; toxicity

OBJECTIVETo study the effects of aluminum citrate (AC), rare earth compounds (REC) and sodium selenite (SS) on the surface elements of chrysotile fibers and the inhibitory mechanisms of three compounds for chrysotile-induced biological activities.

METHODSAfter being soaked in 250, 500 and 1000 microg/ml aluminum citrate solutions, 125, 250, 500 and 1000 microg/ml mixed rare earths solutions or 125, 250, 500 and 1000 microg/ml sodium selenite solutions for 10 min or 1 hour, the fabrication and the levels of surface elements of chrysotile fibers were determined.

RESULTSAluminum citrate, mixed rare earths or sodium selenite all could be adsorbed by chrysotile fibers. After pretreatment of chrysotile fibers with aluminum citrate, mixed rare earths or sodium selenite solutions for 10 min or 1 hour, the corresponding elements or ion on the surface of chrysotile fibers increased with the increase of concentration of the solutions.

CONCLUSIONPretreatment of chrysotile with aluminum citrate, mixed rare earths or sodium selenite solutions can change the fabrication and the levels of surface elements of chrysotile fibers, and inhibit the biological activities of chrysotile by "sealing" some "active sites" on the surface of chrysotile fibers.

Asbestos, Serpentine ; chemistry ; toxicity ; Citric Acid ; chemistry ; Metals, Rare Earth ; chemistry ; Sodium Selenite ; chemistry

OBJECTIVETo clarify the dose-response relationship between asbestos dust exposure and lung cancer incidence in chrysotile asbestos miners by fixed cohort study and to investigate the incidence rates of lung cancer in exposure to different concentrations of asbestos dust.

METHODSA retrospective cohort study was conducted in 1932 asbestos miners who registered from January 1, 1981 to December 31, 1988, had worked for at least 1 year, and had no obvious cardiopulmonary diseases; the cohort study began in July 2009 and covered a time span of 29 years (1981 - 2009). The personal information, occupational history, disease history, and health data of these miners were recorded, and the monitoring data on dust concentrations in the mine over the years were collected. The dose-response relationship between asbestos dust concentration and lung cancer incidence was established by the method of life table; a regression equation was fitted to predict the excess incidence rates of lung cancer under the conditions of different working years and dust concentrations.

RESULTSA significant dose-response relationship was observed between cumulative exposure (Ce) and cumulative probability (Px) of lung cancer incidence, and the smokers hada higher Px than nonsmokers. When Ce was less than 2000 mg/m(3)·each year, Px reached 6.58/10000; when Ce was not less than 2000 mg/m(3)·and less than 3000 mg/m(3)·each year, Px reached 91.72/10000; when Ce was more than 5000 mg/m(3)·each year, Px was as high as 141.02/10000. The three models were fitted to obtain the optimal regression equation: Px = -0.0004Ce(2) + 0.0052Ce - 0.0011 (r(2) = 0.9387). In the workshop of asbestos mine in this study, the average dust concentration was 85 times higher than the limit in 2009, so the excess incidence rate of lung cancer was 112.598/10000 if the miners worked under this condition for 40 years, according to the equation.

CONCLUSIONThere is a significant dose-response relationship between cumulative asbestos exposure and lung cancer incidence in chrysotile asbestos miners. The risk for lung cancer rises as asbestos exposure increases.

Asbestos, Serpentine ; toxicity ; Dust ; Female ; Humans ; Lung Neoplasms ; etiology ; Male ; Mining ; Occupational Exposure ; Retrospective Studies

Asbestos is a carcinogen that causes diseases such as mesothelioma and lung cancer in humans. There was a sharp increase in the use of asbestos in Korea in the 1970s as Korea's economy developed rapidly, and asbestos was only recently banned from use. Despite the ban of its use, previously applied asbestos still causes many problems. A series of asbestos-related events that recently occurred in Korea have caused the general public to become concerned about asbestos. Therefore, it is necessary to take proper action to deal with asbestos-related events, such as mass outbreaks of mesothelioma among residents who lived near asbestos textile factories or asbestos mines. Although there have been no rapid increases in asbestos-related illnesses in Korea to date, such illnesses are expected to increase greatly due to the amount of asbestos used and long latency period. Decreasing the asbestos exposure level to levels as low as possible is the most important step in preventing asbestos-related illnesses in the next few decades. However, there is a lack of specialized facilities for the analysis of asbestos and experts to diagnose and treat asbestos-related illnesses in Korea; therefore, national-level concern and support are required.
Asbestos/*toxicity ; Asbestosis/*epidemiology/etiology/mortality ; Environmental Exposure/prevention & control ; Humans ; Korea ; Lung Neoplasms/*chemically induced ; Mesothelioma/*chemically induced/epidemiology

The present review summarizes the results of several follow-up studies assessing an asbestos product manufacturing plant in Chongqing, China, and discusses three controversial issues related to the carcinogenicity of asbestos. The first issue is the amphibole hypothesis, which asserts that the carcinogenicity of asbestos is limited to amphiboles, such as crocidolite, but not serpentines, such as chrysotile. However, considering the possible multiple component of asbestos carcinogenicity in the presence of tobacco smoke or other carcinogens, chrysotile cannot be regarded as non-carcinogenic. Additionally, in a practical sense, it is not possible to assume "pure" chrysotile due to its ubiquitous contamination with tremolite, which is a type of amphibole. Thus, as the International Agency for Research on Cancer (IARC) assessed, all forms of asbestos including chrysotile should be regarded carcinogenic to humans (Group 1). The second issue is the chrysotile/tremolite paradox, which is a phenomenon involving predominant levels of tremolite in the lung tissues of individuals who worked in locations with negligible levels of tremolite due to the exclusive use of chrysotile. Four possible mechanisms to explain this paradox have been proposed but this phenomenon does not support the claim that amphibole is inert. The final issue discussed is the textile mystery, i.e., the higher incidence of cancer in asbestos textile plants compared to asbestos mines where the same asbestos was produced and the exposure levels were comparable. This phenomenon was first reported in North America followed by UK and then in the present observations from China. Previously, levels of fiber exposure were calculated using a universal converting coefficient to estimate the mass concentration versus fiber concentration. However, parallel measurements of fiber and mass concentrations in the workplace and exposed air indicated that there are wide variations in the fiber/mass ratio, which unjustifies the universal conversion. It is possible that contamination by airborne non-fibrous particles in mines with mass fiber conversion led to the overestimation of fiber concentrations and resulted in the textile mystery. Although the use and manufacturing of asbestos has been banned in Japan, more than 10 million tons of asbestos had been imported and the majority remains in existing buildings. Thus, efforts to control asbestos exposure should be continued.
Asbestos ; classification ; toxicity ; Asbestos, Amphibole ; toxicity ; Asbestos, Serpentine ; toxicity ; Carcinogens ; China ; Follow-Up Studies ; Humans ; Lung Neoplasms ; chemically induced ; epidemiology ; Manufacturing and Industrial Facilities ; statistics & numerical data ; Mining ; statistics & numerical data ; Occupational Diseases ; epidemiology ; Occupational Exposure ; adverse effects ; Textiles ; Tobacco Smoking ; epidemiology

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.
Asbestos/toxicity ; Carcinogens/toxicity ; Chromium/toxicity ; Female ; Humans ; Lung Neoplasms/chemically induced/*epidemiology/*etiology ; Male ; Mesothelioma/epidemiology/*etiology ; Occupational Diseases/chemically induced/*epidemiology/etiology ; Occupational Exposure/*adverse effects ; Pneumoconiosis/complications ; Republic of Korea/epidemiology ; Silicon Dioxide/toxicity ; Workers' Compensation

The legal scope and criteria for occupational cancer in Korea was out of date. The aim of this study was to review the current criteria for occupational cancer and amend the existent criteria on the basis of recent scientific evidence. The scientific evidence and the legal list of occupational cancer were analyzed to identify the causes of occupational cancer on a global scale. The relationship between compensated occupational cancer cases and carcinogen exposure in Korea was examined. The factors associated with specific causes and target cancers were determined to produce additional criteria. Five-hundred and nineteen cases of 2,468 were awarded compensation for occupational cancer including lung, malignant mesothelioma, lymphohematopoietic, and liver cancers from January 2000 to October 2012. Between 1996 and 2005, benzene accounted for 84.4% of cases, and between 1999 and 2005, asbestos was associated with 62.3% of cases. Fourteen novel causative agents and 12 additional target cancers were identified and the final guidelines were amended to include 23 causative agents and 21 target cancers. This amendment of the criteria for occupational cancer represents the widest change in Korean history and is expected to improve the understanding of occupational cancer by providing an up-to-date and accurate reference guide.
Asbestos/toxicity ; Benzene/toxicity ; Carcinogens/toxicity ; Female ; Humans ; Insurance, Health/*economics ; Middle Aged ; Neoplasms/chemically induced/*economics ; Occupational Diseases/*economics/mortality ; Occupational Exposure/*adverse effects ; Republic of Korea ; Workers' Compensation/*economics/legislation & jurisprudence/standards

An understanding of the characteristics of occupational lung cancer is important to establish policies that prevent carcinogen exposure and to compensate workers exposed to lung carcinogens. This study analyzed the characteristics of occupational lung cancers in workers who were compensated under the Industrial Accident Compensation Insurance Law between 1994 and 2011. A total of 179 occupational lung cancers were compensated. The main carcinogenic exposure was asbestos, followed by crystalline silica and hexavalent chromium. The mean exposure duration and latency were 19.8 and 23.2 yr. The most common industry was manufacturing, followed by construction and transportation. The most common occupation was maintenance and repair, followed by foundry work, welding, painting, and spinning or weaving. Although asbestos was predominant carcinogen, the proportion of these cases was relatively low compared to other developed countries. Proper surveillance system is needed to monitor occupational lung cancer and improve prevention measures.
Adult ; Aged ; Asbestos/toxicity ; Chromium/toxicity ; Female ; Humans ; Insurance Benefits/legislation & jurisprudence ; Lung Neoplasms/economics/*epidemiology/etiology ; Male ; Middle Aged ; Occupational Diseases/economics/*epidemiology/etiology ; Occupational Exposure ; Republic of Korea/epidemiology ; Silicon Dioxide/toxicity ; Smoking ; Workers' Compensation/statistics & numerical data