Journal of Occupational Health
Online ISSN : 1348-9585
Print ISSN : 1341-9145
ISSN-L : 1341-9145
Volume 44, Issue 2
Displaying 1-10 of 10 articles from this issue
Review
  • Hideki IGISU, Masato MATSUOKA
    Article type: Review
    Subject area: Others
    2002 Volume 44 Issue 2 Pages 63-68
    Published: 2002
    Released on J-STAGE: November 29, 2002
    JOURNAL FREE ACCESS
    Although the toxic effects of acrylamide on the peripheral nervous system have been well established, less attention has been paid to its effects on the brain. Nevertheless, (1) ultrahigh field magnetic resonance imaging revealed enlarged cerebral ventricles and cisterns in rats treated with acrylamide 50 mg/kg/d for 8 d, (2) creatine kinase (CK) activities were suppressed in the brain from such rats and mice, (3) CK activities in the brains of mice intoxicated with acrylamide changed in parallel with neurological dysfunction, (4) in human cases of acrylamide intoxication due to occupational exposure, symptoms suggesting brain involvement were seen in a few, and (5) cases of acrylamide intoxication due to contaminated well water showed unquestionable signs of brain dysfunction including mental confusion with hallucinations. These indicate that acrylamide can cause encephalopathy in animals as well as in humans, and that the spectrum of impairment of the nervous system can vary greatly depending on the mode of exposure.
    Download PDF (1240K)
Originals
  • Takehiko ITO, Kei YOSHITOME, Tokushi HORIKE, Shohei KIRA
    Article type: Original
    Subject area: Others
    2002 Volume 44 Issue 2 Pages 69-75
    Published: 2002
    Released on J-STAGE: November 29, 2002
    JOURNAL FREE ACCESS
    Organic solvents generally depress the central nervous system (CNS), similarly to volatile anesthetics. The precise mechanism of their action on the CNS, however, is not fully understood, and remains to be clarified. This study is focused on how inhaled m-xylene distributes in the brain, and whether region specific change in GABAA receptor binding takes place due to the exposure. To conduct this study, we first developed a simple exposure system suitable for inhalation experiments with small animals. Using this system, six-week-old male Sprague-Dawley rats were exposed to m-xylene vapor (2000 ppm) 4 h/d, for 5 consecutive days. At the end of the exposure, m-xylene levels in four different regions of the brain were measured by head-space gas chromatography. Also 14 μm-thick frozen sections of the brain were made, and [35S] t-butylbicyclophosphorothionate (TBPS) binding autoradiography was performed. Uneven distribution of m-xylene in the brain was observed. The concentration in the cerebellum (976±93.4 μg/g tissue) was the highest, while that in the cerebral cortex (467±43.6 μg/g tissue) was the lowest. [35S]TBPS binding was significantly greater in the molecular layer of the cerebellum (control: 12.6 0.64, m-xylene 16.0±1.34 fmol/mg tissue). These results suggest that m-xylene is distributed unevenly in the rat brain, and acute exposure to m-xylene at a high concentration alters [35S]TBPS binding, which may reflect changes in GABAA receptor characteristics.
    Download PDF (1240K)
  • A Prospective Cohort Study
    Li KE, Yu SHUNZHANG
    Article type: Original
    Subject area: Others
    2002 Volume 44 Issue 2 Pages 76-82
    Published: 2002
    Released on J-STAGE: November 29, 2002
    JOURNAL FREE ACCESS
    To determine the specific causes of mortality in the rubber industry with emphasis on the associations between cancer sites, ischemic heart, and cerebrovascular disorders and work places, A cohort of 1598 rubber workers (934 men, 664 women) were followed up for mortality from 1 January 1973 to 31 December 1997. Work histories of cohort members at the relevant work place were coded and computed by the factory personnel concerned and the record incorporated all job changes with relevant years. Standardized mortality ratios (SMRs) and 95% confidence intervals (95% CIs), controlling for age and calendar year and stratified by work area (employment in respective work areas for at least one year) were calculated from the reference rate. Significant increases in mortality were found for lung cancer among male workers in the curing department (16 deaths, 6.7 expected, SMR 2.39), liver cancer among male workers in the rubber overshoes department (2 deaths, 0.2 expected, SMR 10.00), cerebrovascular disorders among male workers in the rubber overshoes department (4 deaths, 1.0 expected, SMR 4.00), and cerebrovascular disorders among female workers in the mixing and milling department (7 deaths, 2.0 expected, SMR 3.50). Mortality from the remaining cancers was not substantially increased in any of the work departments. Mortality from several diseases was associated with specific work departments. Some of these associations have been reported previously and they may be causally related to occupational exposure in this industry, for example, lung cancer and the curing department. The study also found new risks, such as a possible increase in cerebrovascular disorders.
    Download PDF (522K)
  • —Winter-Summer Difference and Effect of Protective Masks in Practical Working Conditions—
    Tsukasa INAOKA, Megumi NAGANO, Takao KITANO, Kayo USHIJIMA, Keiko MINA ...
    Article type: Original
    Subject area: Others
    2002 Volume 44 Issue 2 Pages 83-88
    Published: 2002
    Released on J-STAGE: November 29, 2002
    JOURNAL FREE ACCESS
    Objective: Studies were carried out in Kumamoto, Japan to examine 1) the winter-summer differences in the average individual exposure to styrene (8hr-TWA) and to end-shift-urinary mandelic acid (MA in g/g Cr), 2) the possible seasonal difference in their relationship, and 3) the protective effect of a disposable particulate respirator containing charcoal fiber (called a “charcoal mask”) and a charcoal granule cartridge-mask (called a “gas mask”) in the real working conditions. Methods: Approximately 100 male and female workers from about 10 small industries were subjected to the studies first in winter and second in summer. Individual exposure to styrene was monitored with a passive sampler during work time, and end-shift-urine was collected to determine urinary MA excretion. The content of their activities and the types of protective equipment were observed and recorded by the minute throughout the working day. Results: Neither individual exposure to styrene nor urinary MA excretion differed at the time of the study in both “no-mask” and “gas mask” groups. The urinary MA excretion was related to individual exposure to styrene in both seasons, with the highest correlation coefficient in the “no-mask” group. Since the regression slope for the “charcoal mask” group did not differ from that for “no-mask” group, the “charcoal mask” was judged to have little protective effect in practical working conditions. From the difference in urinary MA values at 50 ppm (previous TLV-TWA by ACGIH) of individual exposure to styrene in the two regressions for “no-mask” and “gas mask” groups, 49% of styrene was protected against by the “gas mask” in winter, and 45% in summer. Conclusions: Despite different physical environmental conditions, individual exposure to styrene and urinary MA excretion did not differ by season in FRP-making industries. A “gas mask” is more recommended than a “charcoal mask” when treating styrene, although their protective effects are decreased in practical working settings. It is basically necessary to give correct information on and free access to such protective equipment to styrene-treating workers.
    Download PDF (494K)
  • Hidemaro TAKEYAMA, Toru ITANI, Norihide TACHI, Osamu SAKAMURA, Hatsuko ...
    Article type: Original
    Subject area: Others
    2002 Volume 44 Issue 2 Pages 89-98
    Published: 2002
    Released on J-STAGE: November 29, 2002
    JOURNAL FREE ACCESS
    An experimental study was carried out under simulated shift-work schedules to examine the effects of a nighttime nap on task performances and psycho-physiological functions on morningness (M-types) and eveningness (E-types) subjects. Sixty male students, classified as M-types or E-types by the Japanese version morningness-eveningness questionnaire, were recruited for this study. Five moderate M-types and eight moderate E-types were selected. Their MEQ scores were 32-41 (average 36.9) in E-types and 60-64 (average 62.4) in M-types, respectively. Experiment periods were simulated shift schedules of 9 consecutive days consisting of 2 d shifts (working 8:00-16:00), 3 night shifts (working 22:00-8:00) and 3 d shifts. They carried out two series of experiments. In one series the subjects took a nap from 2:00 to 4:00. In the other series they did not take a nap during the night shift. In order to minimize the effect of the previous experiments, a rest period of more than one week was inserted between the nap-condition and the no-nap condition experiments. During the shifts, the subjects repeatedly performed two kinds of tasks: typing figures listed randomly on sheets into a computer for 20 min; and after a 5 min break performing mental arithmetic with two adjacent figures, listed randomly on the sheets, for 15 min. During the breaks, psycho-physiological functions and questionnaires on subjective feelings of fatigue and index of the state of anxiety were examined. Throughout the experiments, heart rate variability was also recorded with a portable recorder to evaluate autonomic nerve activity. Task performances decreased and subjective feelings of fatigue and anxiety scores increased in proportion to the length of time worked in both M-types and E-types who had no nap. In M-types, these changes were significantly suppressed by the nap on the first night of duty. Parasympathetic nerve activity for M-types estimated from heart rate variability between 4:00 and 6:00 under nap conditions decreased significantly compared with that under no-nap conditions. Overall changes for E-types, however, were smaller than those for M-types in terms of task performance and psycho-physiological parameters. The present study suggested that taking a nighttime nap was an effective way to reduce adverse effects due to first nocturnal work, especially for M-types.
    Download PDF (913K)
Short Communications
Field Studies
  • Yong Chul SHIN, Gwang Yong YI, Tae-Kyun KIM, Nam-Seok SOHN, Jungsun PA ...
    Article type: Field Study
    Subject area: Others
    2002 Volume 44 Issue 2 Pages 108-111
    Published: 2002
    Released on J-STAGE: November 29, 2002
    JOURNAL FREE ACCESS
    Hepatic dysfunction in workers exposed to HCFC-123 has recently been reported, but information on the level of exposure to the material and the related hepatotoxicity in workers handling the material is very limited. This study evaluated the exposure status in some Korean workers handling the chemical and whether they have liver dysfunction. We investigated all four factories manufacturing large-sized industrial air-conditioners operating in South Korea in 1998. The range and geometric mean of the estimated 8-hour TWA concentrations at two factories were 2.2 ppm (0.89-4.2 ppm) and 32.5 ppm (4.9-113.9 ppm), respectively. It was estimated that the HCFC-123 concentrations at the other two factories were lower than those at the former two. Liver function was within the normal range in all the exposed workers. The present study did not show any health effect of HCFC-123 on workers. Worker exposure in this study was intermittent and lower than in studies which reported cases of liver dysfunction, so that the level and pattern of exposure to HCFC-123 would be very important as a cause of liver dysfunction. Our study showed that liver dysfunction did not occur at an exposure concentration less than 32.5 ppm as an 8-hour TWA of HCFC-123.
    Download PDF (323K)
  • Abdel Hameed A. AWAD
    Article type: Field Study
    Subject area: Others
    2002 Volume 44 Issue 2 Pages 112-118
    Published: 2002
    Released on J-STAGE: November 29, 2002
    JOURNAL FREE ACCESS
    Airborne viable and non-viable measurements were carried out in two different metro stations, one located in a tunnel and the other on the surface. The concentrations of airborne total viable bacteria (incubated at 37°C and 22°C), staphylococci, suspended dust and oxidants (ozone) were higher in the air of the tunnel station than those recorded at the surface station. In contrast, spore forming bacteria, Candida spp, fungi and actinomycetes were found at slightly higher levels in the surface station than in the tunnel station. A statistically significant difference (p<0.01) was found between the levels of suspended dust at both stations. Cladosporium, Penicillium and Aspergillus species were the dominant fungi isolates. Fusarium, Aspergillus and Penicillium are the most common fungi that produce toxins. Under certain circumstances (host susceptibility, infective dose and aerodynamic diameter) some of the airborne microorganisms e.g. actinomycetes and Aspergillus species and staphylococci may cause health problems in exposed persons based on toxic or allergic reactions.
    Download PDF (574K)
feedback
Top