The present review was aimed to determine the influence of working conditions, occupational exposures to potential chemical and physical reproductive toxic agents and psychological stress during work on male fertility. Significant associations were reported between impaired semen parameters and the following chemical exposures: metals (lead, mercury), pesticides (dibromochlorophane, 2, 4-dichlorophenoxyacetic acid), ethylene glycol ethers and estrogens. The following physical exposures were shown to deteriorate sperm parameters: radiation (both ionized and microwaves) and heat. Psychological distress has another important contribution to infertility. Several studies indicated that stress has a negative impact on sperm parameters. Occupational parameters should be an important part of history taking among patients attending infertility clinics.
Trace elements are analyzed in the human scalp hair to assess the extent of body burden of pollution. The levels of seven elements (Cd, Cr, Cu, Mn, Ni, Pb and Zn) were determined in the hair of fishermen from Pondicherry, students and businessmen from Madras and non-mining workers from Neyveli lignite open mine. When compared between them, significantly high concentrations of Cd in the non-mining workers from Neyveli and Pb in both the students and businessmen from Madras were observed, thereby indicating environmental source of Cd and Pb pollution. The low Zn level was observed in the fishermen indicating their low nutritional source. In addition to the different residential areas, age, diet, smoking habit and family income of subjects are other factors influencing the concentrations of elements in the hair.
The present study, consisted of two separate surveys, was initiated to clarify the development of clinical pictures of silicosis after termination of dust exposure. The first survey was a 40-year follow-up of radiographic pictures of the chest among 200 male whetstone cutters (Group I workers). The second survey was conducted in 75 male recipients (Group II workers) of disability compensation for silicosis due to whetstone dust exposure. The study on Group I workers made it clear that the proportion of those free of radiographic findings in the chest pictures decreased during a 40-year follow-up period from 84% in the 1st health examination in 1952-6 to 36% in the 3rd examination in 1995. The rate of progression of the disease from Category 1 to 3 (after ILO-guided classification) to higher categories in a 15-year period was as high as >50%. Longer service duration and higher category of chest radiography at the previous health examination were the influential factors in determining the rapid progression of silicosis. The latter observation was confirmed also through a similar analysis on Group II workers. Whetstone preparations contained SiO2 by about 50%. No industrial hygiene data were available for both groups of stone cutters, but the exposure of Group I workers was estimated to be about 1 mg/m3, or well in excess of the current occupational exposure limit.
We initiated an investigation to examine the possible association between the cancer risk and the chlorinated organic solvents exposure in an electronic factory. To obtain information on the incidence of the various types of cancer among the exposed and comparison groups, the cohort populations were merged with the National Mortality Database, the National Cancer Registry Database, and the National Insurance Hospitalization Database from the Department of Health (DOH), as well as the Labor Insurance Hospitalization Database from the Bureau of Labor Insurance (BLI). The proportionate cancer morbidity ratio (PCMR) was used to estimate the cancer risk of the exposed workers in comparison with either textile workers or electronics workers. After adjustment for age, only the PCMR for breast cancer in the exposed female employees was significantly elevated when compared with the two comparison groups. The increased risk of breast cancer was mainly found in the category of 1989-1997 for year of diagnosis when stratified by calendar year. However, there was no dose-response relationship between female breast cancer risk and duration of employment. Although some PCMRs for the cancers were also increased in the exposed group, female breast cancer was consistently increased when compared with both textile and electronics comparison groups using different exclusion criteria. The results obtained in the present study suggest a possible association between exposure to chlorinated organic solvents and female breast cancer. Since this association has never been reported in the previous studies, further studyis needed to clarify the association.
Human beings always suffer from serious risk of exposure to ultraviolet (UV) rays in general as well as in work environments but the health effects of UV are not yet fully understood. To enable fine analysis of the biological effects of UV at any given wavelength, we developed an apparatus that can experimentally irradiate cultured mammalian cells with monochromatic UV rays at any given wavelength. With this device, the effects of UV at 260, 280, 300 and 320 nm on the total protein synthesis of human skin-derived NB1RGB cells were examined. An inhibitory effect of UV at 260 and 280 nm was evident, whereas UV at 300 and 320 nm had only a marginal effect. UV at 280 nm also decreased amino acid uptake, which appears, at least partly, to be responsible for reduced protein synthesis. Metallothioneins (MTs), known as proteins defending against heavy metal toxicity, have been reported to be induced after UV irradiation, but UV at 280 nm did not induce MTs in NB1RGB cells. Cadmium pretreatment of cells, that had been assumed to protect cells from UV damage via MT induction, did not increase cell viability after exposure to UV at 280 nm. The present study unambiguously revealed the biological effects of monochromatic UV rays, also showing that the UV-irradiating apparatus can be a powerful tool for studying the health effects of UV.
We analyzed the characteristics of 120 patients of primary lung cancer supposed to be induced by exposure to asbestos. Most of 120 patients were male and the age ranged from 47 to 87 years with a median of 70 years. No particular tendency was observed in the histological types of the lung cancer in 120 patients. Forty of the 120 patients were heavy smokers. When the occupational history was analyzed, most of the patients had been exposed to asbestos in former Japanese naval shipyard, commercial shipyards, construction industry and ironworks. The term of asbestos exposure was 2 to 60 years with a median 27 years. Lung cancers appeared after 15 to 69 years with a median 43 years from the initial exposure to asbestos. Lung cancer was accompanied by asbestosis in 35 patients and by pleural plaques in 77. Twenty-two patients had both asbestosis and pleural plaques. The number of asbestos bodies per 5 g wet lung tissue for 72 patients whose lung tissues obtained from autopsy or surgery was more than 150 bodies which meant the number of occupational asbestos exposure. As for the kinds of asbestos fibers of 32 patients, 14 patients exposed to crocidolite, 10 patients to amosite and 8 patients to chrysotile.
A prospective study examined whether working 50 hours or less per week was associated with an increase of mental and circulatory disorders, and if so, whether it was significant for managing workers' health. White-collar workers aged 20 to 60 working at an office of a Japanese company were surveyed from August 1997 to March 2001. The onsets of the diseases were confirmed using medical insurance claims, and the overall incidence rates were 6.6 and 15.7 per 10, 000 person months for both the disorders, respectively. Though not significant, those who worked 45 hours or more showed higher relative risks for mental disorders compared with those who did not. No other analysis indicated distinct findings. The small number of onsets of the diseases, the attention to personal health for workers who worked shorter hours, and intensive health care system for circulatory diseases in the workplace may partly account for the findings above. However, through reviewing other reports, it was suggested that the perception of work time could disturb the association between these findings, especially for white-collar workers. Also, it might be useful to observe the onset of mental disorders in work of less than 50 hours with the workers' perception of work time.
One hundred and sixty-nine and 175 cotton textile workers (CTWs) were enrolled in the first (1991) and second (1996) surveys to investigate the prevalence of byssinosis. The synergistic effect of smoking on cotton dust exposure was also evaluated. Although the difference in prevalence of abnormal pulmonary function between the first (38.5%) and second study (38.9%) was not statistically significant, smokers had significantly higher frequency than nonsmokers in both surveys. A significant trend existed between the cotton dust levels and the frequency of abnormal lung function. The significant trend was also noted in both smokers and nonsmokers. The frequency of respiratory symptoms and the prevalence of severe byssinosis in the second survey (14.9% and 12.6%, respectively) were significantly lower than that in the first survey (39.7% and 21.9%, respectively). The reduction of symptoms was due to remodeling of this old cotton mill. The prevalences of respiratory symptoms and byssinosis in smokers being significantly higher than in nonsmokers only found in the first survey, but not found in the second survey. These results indicate that smoking potentiates the effect of cotton dust exposure on respiratory symptoms and byssinosis. The second study reveals high prevalence of byssinosis still existed in Taiwanese cotton mill, although the prevalence was declining. Smoking was found to show an additive effect on cotton dust exposure. Anti-smoking campaign, occupational health program to reduce the dust exposure, and periodical medical examination are measures to prevent from byssinosis.
The aim of this study was to compare the consultation rates (CR) of workers performing several types of white-collar jobs. We collected data from the database inputted at the first consultation to a health care center from April 1996 to March 1999. We found that the CR of engineer group was 2.3 times higher than that of employees involved in research and development group. We speculate that this is partially due to the portion, which is not small, of computer systems engineer (SE) comprising this group; SE has previously been mentioned as a particularly stressful occupation in Japan. Since the result of this study is preliminary, we need to conduct a further study taking into account that multiple factors affect CR.
This paper presents the profile of occupational respiratory diseases in the Czech Republic. In a retrospective study the author analyzes structure, causes, occurrence, and trends of occupational diseases. Between 1996 and 2000, a total of 2, 127 new cases were recorded, of which 62.0% were pneumoconioses caused by dust containing free silica, 21.0% were occupational asthma or allergic rhinitis and the rest were divided between lung cancer (10.0%), asbestos-related disorders (4.4%) and variety of other respiratory diseases (2.7%). During the period of the investigations, the decreasing trend of occupational respiratory diseases, which began in 1992, has continued.