In a study of 142 Japanese men from a cross-section of the workforce of a technology development company, we found that the percentage of CD56+ cells was inversely correlated with the number of hours worked per week. A low CD56+ cell percentage was associated with longer weekly working hours and shorter daily sleeping hours.
The medical examination of workers exposed to lead was conducted as part of the activity of the Occupational Safety and Health Center (OSHC) Project in the Philippines (JICA Project).The subjects of the medical examination were 21 male and 193 female workers of a semiconductor plant (abbreviated A company), 59 male and 6 female workers of a refrigerator manufacture (B company); 199 male workers of a storage battery manufacturer (C company); and 107 male and 6 female workers of a lead smelter (D company). Among the examination items were questions regarding occupational history, subjective complaints and objective signs, determination of blood lead levels, urine deltaaminolevulinic acid levels, and examination for anemia. The survey was conducted from June to September in 1990.The following results were obtained:1) The mean age of the workers ranged from 21.8 to 33.8 years. Those of companies A and B were younger than those of companies C and D. The mean employment duration of males at C company was 10.7 yr, and the longest among the four companies. That in both sexes for A company was 1.8 yr and the shortest among the above mentioned companies.2) The blood lead geometric mean levels of compamies C and D showed the highest concentration. The level in males of C company was 64.5 μg/dl and that of D company was 80.8 μg/dl. The level in females of A company was 9.9 μg/dl and the lowest in concentration. The urine deltaaminolevulinic acid geometric mean levels were less than 6.0 mg/l in the four companies. There was no company having hemoglobin mean values less than 14.0 g/dl in males or less than 12.0 g/dl in females.3) The proportion of blood lead levels of 60 μg/dl or more was 67.3% in males of C company, and 89.7% in males and 16.7% in females of D company. The proportion of urine deltaaminolevulinic acid levels of 6 mg/l or more was 1.0% in females of A company, 20.1% in males of C company, and 43.0% in males of D company. The proportion of hemoglobin values less than 14.0 g/dl in males or less than 12.0 g/dl in females was 4.7% in females of A company, 1.7% in males of B company, 3.5% in males of C company, and 12.1% in males of D company.4) The symptoms having a prevalence of more than 10% in males were easy fatigability and malaise for A company; irritability, joint pains, muscle pains and paraesthesia for B company; all items for C company; and easy fatigability, malaise, irritability, sleep disorder, joint pains, muscle pains, abdominal discomfort and paraesthesia for D company. Those in females were easy fatigability, malaise, irritability, sleep disorder, joint pains, and muscle pains for A company.5) A relationship between the prevalence of symptoms and blood lead levels was observed. In males. there were significant group differences in the symptoms of easy fatigability, malaise, irritability, sleep disturbance, joint pains, muscle pains, abdominal colic, abdominal discomfort, constipation/diarrhea and paralysis/paresis of the extensor muscles (p<0.05 or p<0.01). With some exceptions, a trend of increasing prevalence with increasing blood lead level was observed. There were no significant differences in females.6) In males having a blood lead level less than 40 μg/dl, there were significantly positive correlations between age and duration of employment and between blood lead level and duration of employment (p<0.001); and in females, there were significantly positive correlations between age and duration of employment and between blood lead level and hemoglobin values (p<0.05). In males having a blood lead level more than 40 μg/dl, there were significantly positive correlations between age and duration of employment and between blood lead level and urine deltaaminolevulinic acid level (p<0.001)
Background. Pulmonary fiber content of both asbestos and nonasbestos types were evaluated in Japanese patients with malignant pleural mesotheliomas. Methods. Pulmonary fiber content was analyzed in 16 patients and 16 case-matched control subjects by transmission electron microscopy with energy-dispersive X-ray analysis using a low-temperature ashing procedure. Results. The geometric mean content of total asbestos was significantly higher in the patients (22.0 × 106 fibers/g dry lung) than in the control subjects (2.24 × 106 fibers/g dry lung) (P < 0.01). When the asbestos content was analyzed by fiber type, the geometric means were also consistently and significantly higher among the patients compared with the control subjects (P < 0.01). Results were as follows: (1) amosite: patients 3.94 times 106 versus control subjects 0.23 × 106; (2) crocidolite: patients 3.56 times 106 versus control subjects 0.35 times 106; (3) total amphiboles: patients 16.0 times 106 versus control subjects 0.77 times 106; and (4) chrysotile: patients 3.76 times 106 versus control subjects 1.01 times 106. However, when individual total asbestos content was considered, 7 of the 16 patients (44%) had levels lower than the highest value noted among the control subjects. Pulmonary fiber content of patients and control subjects also revealed the presence of nonasbestos fibers. The geometric mean of nonasbestos fibers was significantly higher in the patients (87.3 × 106) than in control subjects (33.8 × 106) (P × 0.01). The major type of nonasbestos fibers in both groups was aluminum silicates. The mean of ratios of nonasbestos fiber contents to total asbestos contents in the patients and control subjects was 7.0 and 17.3, respectively. Conclusions. The results were mainly in agreement with the findings of earlier investigations, but fiber content of both chrysotile and nonasbestos fiber as well as those of amphibole asbestos were significantly higher in the patients than in the control subjects.
Both airborne asbestos and non-asbestos fiber concentrations were evaluated in Korean non-occupational environments. The airborne fiber concentrations were analyzed in 96 air samples, from 48 different points, by transmission electron microscopy, with energy-dispersive X-ray analysis. The geometric means of the airborne asbestos and non-asbestos fiber concentrations were 0.62 and 67.86, and 0.30 and 17.47 fibers/liter in urban and rural areas, respectively. There were significant differences in both the airborne asbestos and non-asbestos fiber concentrations between the urban and rural areas (p<0.05). The geometric means of airborne asbestos and non-asbestos fiber concentrations were 0.67 and 37.93, and 0.27 and 30.67 fibers/liter at the points less than 10 m and more than 30 m away from highways, respectively. The airborne asbestos concentrations were significantly higher at the points less than 10 m away than at the points more than 30 m away from highways (p<0.01).
Asbestos causes lung cancer and malignant mesothelioma, and chronic inflammation is considered to participate in carcinogenesis. However, biomarkers to evaluate its carcinogenic risk have not been established. Reactive oxygen/nitrogen species are generated in biological systems under inflammatory conditions and may contribute to carcinogenesis by causing DNA damage. In this study, we examined the relationship between the formation of 8-nitroguanine (8-nitroG), a mutagenic DNA lesion formed during inflammation, and asbestos contents in human lung tissues.We obtained non-tumor lung tissues from patients with (n=15) and without mesothelioma (n=21). The expression of 8-nitroG and related molecules was examined by immunohistochemistry, and their staining intensities were semiquantitatively evaluated. Asbestos contents in lung tissues were analyzed by analytical transmission electron microscopy.In subjects without mesothelioma, staining intensities of 8-nitroG and apurinic/apyrimidinic endonuclease 1 (APE1) were significantly correlated with total asbestos and amphibole contents (p<0.05), but not with chrysotile content. In mesothelioma patients, their staining intensities were not correlated with asbestos contents. The double immunofluorescence technique revealed that APE1 was expressed in 8-nitroG-positive cells, suggesting that abasic sites were formed possibly due to the removal of 8-nitroG. The staining intensities of 8-oxo-7,8-dihydro-2'-deoxyguanosine, an oxidative DNA lesion, and its repair enzyme 8-oxoguanine DNA-glycosylase were correlated with age (p<0.05), but not with asbestos contents in subjects without mesothelioma.This is the first study to demonstrate that 8-nitroG formation is associated with asbestos contents in human lung tissues. This finding raises a possibility that 8-nitroG serves as a biomarker that can be used to evaluate asbestos exposure and carcinogenic risk.
'%3e%3ccircle r='20' fill='%23008'/%3e%3ccircle r='17.5' fill='%23fff'/%3e%3ccircle r='3.5' fill='%23008'/%3e%3cg id='d'%3e%3cg id='c'%3e%3cg id='b'%3e%3cg id='a' fill='%23008'%3e%3ccircle r='.875' transform='rotate(7.5 -8.75 133.5)'/%3e%3cpath d='M0 17.5.6 7 0 2l-.6 5L0 17.5z'/%3e%3c/g%3e%3cuse xlink:href='%23a' transform='rotate(15)'/%3e%3c/g%3e%3cuse xlink:href='%23b' transform='rotate(30)'/%3e%3c/g%3e%3cuse xlink:href='%23c' transform='rotate(60)'/%3e%3c/g%3e%3cuse xlink:href='%23d' transform='rotate(120)'/%3e%3cuse xlink:href='%23d' transform='rotate(-120)'/%3e%3c/g%3e%3c/svg%3e)
