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

OBJECTIVETo understand the toxic effects of manganese exposure on health by measurement of manganese concentration and occupational health inspection among workers in an enterprise exposed to manganese, and to provide a basis for occupational disease control.

METHODSThe air concentrations of manganese in 12 workplaces where workers often stayed were measured by typical sampling; occupational health inspection was performed among a total of 538 workers in the enterprise by cluster sampling.

RESULTSThe average concentrations of manganese in the workplace from 2011 to 2013 were 0.179 mg/m(3), 0.122 mg/m(3), and 0.082 5 mg/m(3), respectively, indicating a significant decrease in manganese level within the three years by rank-sum test (P < 0.05). The results of health inspection showed that 165 (30.7%) out of 538 workers had abnormal indices, and the incidence of autonomic nervous system abnormalities reached 32.7% (176/538). There was no correlation between manganese concentration in the workplace and the incidence of abnormal indices in health inspection, while the manganese concentration in the workplace was positively correlated with the incidence of autonomic nervous system symptoms (r = 0.718, P < 0.05).

CONCLUSIONThe manganese concentration in the workplace is positively correlated with the incidence of autonomic nervous system symptoms. Early exposure to a low level of manganese can induce functional changes and potential damages in the nervous system.

Humans ; Incidence ; Manganese ; analysis ; Nervous System ; drug effects ; physiopathology ; Occupational Diseases ; chemically induced ; epidemiology ; Occupational Exposure ; analysis ; Occupational Health ; standards ; Workplace

Exposure to cephalosporins could cause occupational allergic diseases in health care workers (HCWs). We evaluated the prevalence of serum specific IgE and IgG antibodies to cephalosporin-human serum albumin (HSA) conjugate and to identify potential genetic risk factors associated with sensitization to cephalosporins in exposed HCWs. The study population consisted of 153 HCWs who had been exposed to antibiotics in a single university hospital and 86 unexposed healthy controls. A questionnaire survey of work-related symptoms (WRS) was administered. A skin-prick test (SPT) was performed, and serum-specific IgE and IgG antibodies to 3 commonly prescribed cephalosporins were measured by ELISA. Four single-nucleotide polymorphisms of the candidate genes related to IgE sensitization were genotyped. The prevalence of WRS to cephalosporins was 2.6%. The prevalence rates of serum-specific IgE and IgG antibodies to cephalosporins were 20.3% and 14.7%, respectively. The FcepsilonR1beta-109T > C polymorphism was significantly associated with IgE sensitization to cephalosporins in HCWs (P = 0.036, OR = 3.553; CI, 1.324-9.532). The in vitro functional assay demonstrated that the T allele of FcepsilonR1beta-109T had greater promoter activity than did the C allele (P < 0.001). The FcepsilonR1beta-109T > C polymorphism may be a potential genetic risk factor for increased IgE sensitization to cephalosporins.
Adult ; Alleles ; Anti-Bacterial Agents/analysis/*immunology ; Cephalosporins/analysis/*immunology ; Enzyme-Linked Immunosorbent Assay ; Female ; Genetic Predisposition to Disease ; Health Personnel ; Humans ; Hypersensitivity/*diagnosis/epidemiology ; Immunoglobulin E/blood ; Immunoglobulin G/blood ; Male ; Occupational Diseases/*chemically induced/epidemiology ; Occupational Exposure ; Odds Ratio ; Questionnaires ; Receptors, IgE/genetics ; Skin Tests ; Young Adult

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

In this article, current status of noise exposure in workplaces, trend of workers with noise-induced hearing loss (NIHL), and prevalence of NIHL in workers by industry and job category in Korea were reviewed. In addition, trends of research on the audiological effects such as hearing loss from noise and occupational hearing loss from non-noise in Korea were addressed through reports in industrial audiology. Though noise exposure level has improved, noise still shows the highest rate of cases exceeding exposure limit among workplace hazards. NIHL is the most common occupational disease except work-related disease such as musculoskeletal disorders and cerebrovascular diseases, and NIHL prevalence is thought to be much higher than reported in official publications. Noise affecting hearing comes from various sources such as workplaces, military settings, areas with exposure to high noise, and specific noise sources. There is also occupational hearing loss by non-noise including chemicals such as organic solvents and heavy metals, barotrauma, and trauma due to welding spark. Noise affects daily life through audiological effects such as hearing loss and tinnitus, non-audiological physical effects (e.g., cardiovascular), and psychosocial and behavioral effects. Development of systematic and comprehensive hearing conservation programs for lowering the noise level in workplaces and preventing the NIHL, and preparation of technological, administrative system for its settlement at workplace are urgently needed.
Hearing Loss/*chemically induced ; Hearing Loss, Noise-Induced/*epidemiology ; Humans ; Noise, Occupational/*adverse effects ; Occupational Diseases/chemically induced/*epidemiology/*etiology ; Occupational Exposure/adverse effects ; Prevalence ; Republic of Korea/epidemiology ; Tinnitus/epidemiology

Skin disease is the most common occupational disease, but the reported number is small in Korea due to a difficulty of detection and diagnosis in time. We described various official statistics and data from occupational skin disease surveillance system, epidemiological surveys and cases published in scientific journals. Until 1981, 2,222 cases of occupational skin disease were reported by Korean employee's regular medical check-up, accounting for 4.9% of the total occupational diseases. There was no subsequent official statistics to figure out occupational skin diseases till 1998. From 1999, the Korea Occupational Safety and Health Agency (KOSHA) published the number of occupational skin diseases through the statistics of Cause Investigation for Industrial Accidents. A total of 301 cases were reported from 1999 to 2007. Recent one study showed the figures of compensated occupational skin diseases. Many of them belonged to daily-paid workers in the public service, especially forestry workers. Also, it described the interesting cases such as vitiligo and trichloroethylene-induced Stevens-Johnson Syndrome. Skin diseases are still important though the number of cases has decreased, and therefore it is recommended to grasp the status of occupational skin diseases through continuous surveillance system and to make policy protecting high-risk group.
Adult ; Aged ; Aged, 80 and over ; Female ; Humans ; Male ; Middle Aged ; Occupational Diseases/*epidemiology ; Occupational Exposure ; Republic of Korea/epidemiology ; Safety Management ; Skin Diseases/*epidemiology ; Stevens-Johnson Syndrome/chemically induced/epidemiology ; Trichloroethylene/toxicity

The purpose of this study was to review occupational reproductive abnormalities and occupational bladder cancer in Korea and to discuss their toxicological implications. Reproductive dysfunction as a result of 2-bromopropane poisoning was first reported in Korean workers. In 1995, 23 of the 33 workers (25 female and 8 male workers) who were exposed to 2-bromopropane during the assembly of tactile switch parts developed reproductive and/or hematopoietic disorders. A total of 17 (68%) workers were diagnosed with ovarian failure. Two of the eight male workers experienced azoospermia and four workers experienced some degree of oligospermia or reduced sperm motility. In summary, 2-bromopropane poisoning caused severe reproductive effects in Korean workers. The prognosis was poor for reproductive dysfunction. A few cases of occupational bladder cancer have been reported in Korea, whereas other cancers of the urinary tract have not been reported after occupational exposure. A few cases of benzidine-induced cancer have been reported in Korea and 592 workers in Japan have received compensation for benzidine and beta-naphthylamine-induced cancer. In conclusion, a few cases of benzidine-induced occupational bladder cancer have been reported in Korea. However, benzidine-induced bladder cancer will likely be an important occupational health issue in Korea in the coming years.
2-Naphthylamine/toxicity ; Azoospermia/chemically induced/epidemiology ; Benzidines/toxicity ; Female ; Humans ; Hydrocarbons, Brominated/toxicity ; Infertility/*chemically induced/*epidemiology ; Male ; Occupational Diseases/*chemically induced/*epidemiology ; Occupational Exposure/adverse effects ; Oligospermia/chemically induced/epidemiology ; Primary Ovarian Insufficiency/chemically induced/epidemiology ; Republic of Korea ; Sperm Motility/drug effects ; Urinary Bladder Neoplasms/*chemically induced/*epidemiology

Occupational hepatic disorders are classified into toxic hepatitis, viral hepatitis, and chemical-induced malignancy in Korea. Toxic hepatitis cases were reported in workers who were exposed to dimethylformamide, dimethylacetamide, or trichloroethylene. Pre-placement medical examination and regular follow-up are necessary to prevent the development of toxic hepatitis. Viral hepatitis was chiefly reported among health care workers such as doctors, nurses and clinical pathology technicians who could easily be exposed to blood. Preventive measures for these groups therefore include vaccination and serum monitoring programs. Hepatic angiosarcoma caused by vinyl chloride monomer (VCM) exposure is a very well known occupational disease and it has not been officially reported in Korea yet. Some cases of hepatocellular carcinoma were legally approved for compensation as an occupational disease largely by overwork and stress, but not supported by enough scientific evidence. Effort to find the evidence of its causal relationship is needed.
Adult ; Drug-Induced Liver Injury/epidemiology ; Female ; Health Personnel ; Hepatitis, Viral, Human/epidemiology/prevention & control ; Humans ; Liver Diseases/*epidemiology/prevention & control ; Liver Neoplasms/chemically induced/epidemiology ; Male ; Middle Aged ; Occupational Diseases/*chemically induced/*epidemiology/prevention & control ; Occupational Exposure/adverse effects ; Republic of Korea/epidemiology ; Young Adult

The purpose of this article was to provide a literature review of occupational neurological disorders and related research in Korea, focusing on chemical hazards. We reviewed occupational neurological disorders investigated by the Occupational Safety and Health Research Institute of Korean Occupational Safety and Health Agency between 1992 and 2009, categorizing them as neurological disorders of the central nervous system (CNS), of the peripheral nervous system (PNS) or as neurodegenerative disorders. We also examined peer-reviewed journal articles related to neurotoxicology, published from 1984 to 2009. Outbreaks of occupational neurological disorder of the CNS due to inorganic mercury and carbon disulfide poisoning had helped prompt the development of the occupational safety and health system of Korea. Other major neurological disorders of the CNS included methyl bromide intoxication and chronic toxic encephalopathy. Most of the PNS disorders were n-hexane-induced peripheral neuritis, reported from the electronics industry. Reports of manganese-induced Parkinsonism resulted in the introduction of neuroimaging techniques to occupational medicine. Since the late 1990s, the direction of research has been moving toward degenerative disorder and early effect of neurotoxicity. To understand the early effects of neurotoxic chemicals in the preclinical stage, more follow-up studies of a longer duration are necessary.
Adolescent ; Adult ; Central Nervous System Diseases/chemically induced/epidemiology ; Female ; Humans ; Male ; Middle Aged ; Nervous System Diseases/chemically induced/*epidemiology/etiology ; Neurodegenerative Diseases/chemically induced/epidemiology ; Neurotoxicity Syndromes/*epidemiology/*etiology ; Occupational Diseases/chemically induced/*epidemiology/etiology ; Parkinsonian Disorders/chemically induced/epidemiology ; Peripheral Nervous System Diseases/chemically induced/epidemiology ; Republic of Korea

The purpose of this study was to review the existing studies on lymphohematopoietic (LHP) cancer in Korea, estimate the prevalence of workers exposed to carcinogens, and determine the population attributable fraction (PAF) of leukemia. Two case series and 4 case reports were reviewed. Using official statistics, the prevalence of benzene exposure and ionizing radiation exposure was estimated. Based on the prevalence of exposure and the relative risk, The PAF of leukemia was calculated. Between 1996 and 2005, 51 cases of LHP cancer were reported from the compensation system. Greater than 50% of occupational LHP cancer was leukemia, and the most important cause was benzene. In a cohort study, the standardized incidence ratio was 2.71 (95% CI, 0.56-7.91). The prevalence of exposure was 2.5% and 2.2% in 1995 and 2000, respectively. Using the 1995 prevalence, 3.6-4.8% and 0.1% of cases with leukemia were attributable to benzene and ionizing radiation exposure, respectively, which resulted in 39.7-51.4 cases per year. Benzene is the most important cause of occupational leukemia in Korea. Considering the estimated PAF in this study, the annual number of occupational LHP cancer (51 cases during 10-yr period), might be underreported within the compensation system.
Adult ; Benzene/toxicity ; Cohort Studies ; Female ; Humans ; Incidence ; Leukemia/*chemically induced/*epidemiology ; Leukemia, Radiation-Induced/*epidemiology ; Male ; Middle Aged ; Occupational Diseases/*epidemiology/etiology ; Occupational Exposure/*adverse effects ; Prevalence ; Radiation, Ionizing ; Republic of Korea/epidemiology ; Workers' Compensation