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Peripheral Hemodynamics Evaluated by Acceleration Plethysmography in Workers Exposed to Lead
Yoko AIBA, Satoshi OHSHIBA, Shun'ichi HORIGUCHI, Ikuharu MORIOKA, Kazuhisa MIYASHITA, Ikuko KIYOTA, Ginji ENDO, Haruko TAKADA and Hirotoshi IWATA
Abstract : To clarify the effect of lead exposure on peripheral hemodynamics, acceleration plethysmography (APG) was performed for 48 male subjects occupationally exposed to lead (exposure group) and 43 male subjects with no history of occupational exposure to lead (control group). In the exposure group, the blood lead concentration (Pb-B) was also measured. Each APG parameter was assessed by comparing measured data with the standard aging curves. A significant negative correlation was obtained between the parameter -b/a and Pb-B. The exposure group showed significantly lower values of parameters -b/a (p<0.01) and d/a (p<0.05) than the control group. The parameter -b/a in the exposure group dose-dependently decreased with increases in length of working career (duration of exposure to lead) and Pb-B. The parameter -b/a significantly (p<0.05) decreased in subjects with working careers of 5 years or more and in subjects whose Pb-B was 40 μg/100 ml or more. These results suggest that lead exposure affects peripheral hemodynamics as evaluated by APG.

A Historical Cohort Mortality Study of Workers Exposed to Asbestos in a Refitting Shipyard
Norio KURUMATANI, Yuuji NATORI, Rika MIZUTANI, Shingi KUMAGAI, Meirou HARUTA, Hirotaro MIURA and Kunio YONEMASU
Abstract : To investigate the risks of developing asbestos-related diseases we conducted a historical cohort mortality study on 249 ship repair workers (90 laggers and 159 boiler repairers) in a single U.S. Navy shipyard in Japan. We successfully identified the vital status of 87 (96.7%) laggers and 150 (94.3%) boiler repairers, and, of these, 49 (56.3%) and 65 (43.3%) died, respectively, during the follow-up period from 1947 till the end of 1996. Our in-person interviews with some of the subjects clarified that asbestos exposure was considered to be substantially high in the 1950-60s, decreased thereafter gradually but remained till 1979 in the shipyard. The laggers, who had handled asbestos materials directly, showed a significantly elevated SMR of 2.75 (95% C.I.: 1.08-6.48) for lung cancer. The risk developing the disease was greater in the laggers after a 20-year latency (SMR=3.42). Pancreatic cancer yielded a greater SMR than unity (7.78, 90% C.I.: 2.07-25.19) in a longer working years group. Four laggers died from asbestosis. The boiler repairers, who had many chances for secondary exposure to asbestos and a few for direct exposure, showed no elevation of the SMR of lung cancer overall, but there was a borderline statistically significant SMR of 2.41 (90% C.I.: 1.05-5.45) in a longer working years group. One boiler repairer died from mesothelioma and four from asbestosis.

A Retrospective Cohort Study of Male Workers Exposed to PVA Fibers
Kenji MORINAGA, Kuniomi NAKAMURA, Norihiko KOHYAMA and Takumi KISHIMOTO
Abstract : In order to ascertain whether PVA fibers can produce cancer in humans or not, we have conducted a retrospective cohort study of workers exposed to PVA fibers. A total of 447 exposed and 2416 non-exposed male workers who were engaged before 1980 were followed up until the end of 1996. The SMR for all causes was 0.57 (observed 38, 95%CI:0.41-0.78) for the exposed, and 0.66 (observed 210, 95%CI: 0.58-0.75). As for lung cancer, its SMR was 0.77 (observed 3, 95%CI: 0.15-2.24) for the exposed workers and 0.67 (12 observed, 95%CI: 0.34-1.16) for the non-exposed workers. Lung cancer SMR was 0.86 (observed 2, 95%CI: 0.10-3.11) for the workers with 20 or more years' employment. This study showed no difference in lung cancer risk between the workers exposed to PVA fibers and the non-exposed workers.

The Contribution of Acute Toxicity in Animals to Occupational Exposure Limits of Chemical Substances
Megumi SUDA, Hiroshi TSURUTA and Takeshi HONMA
Abstract : The correlations of lethal doses of various industrial chemicals for rats and mice with occupational exposure limit values were investigated. 50% lethal dose (LD50) values obtained by oral (p.o.) and intraperitoneal (i.p.) injection and 50% lethal concentration (LC50) values obtained by inhalation exposure were collected from Registry of Toxic Effects of Chemical Substances (RTECS). Threshold Limit Value (Time-Weighted Average) (TLVs-TWA) and Threshold Limit Value (Short Term Exposure Limit) (TLVs-STEL) recommended by American Conference of Governmental Industrial Hygienists (ACGIH) were used as exposure limits. TLVs-TWA or TLVs-STEL and LD50 or LC50 values obtained for the rats were plotted on logarithmic scales on the ordinate and abscissa, respectively. High correlations were obtained between these parameters. The order of correlations was: TLVs-STEL vs. LC50s>TLVs-TWA vs. LC50TLVs-TWA vs. LD50s i.p.>TLVs vs. LD50s p.o. The same calculations for the relationship between TLVs and lethal doses in mice were also performed. The order of the three types of correlations was same as that of the rats; however, correlation coefficients for TLVs-STEL vs. LC50s and for TLVs-TWA vs. LC50s obtained in mice were smaller than those in rats. TLVs-TWA are, therefore, well correlated with LC50 values rather than LD50 values, particularly with those in rats. High correlations between TLVs-STEL vs. LC50s were also obtained, as had been expected before calculation. The equation: TLV-TWA=10b x (LC50)a can be obtained from these plottings, where the values a and b are taken from each linear regression line. TLV-TWA for each chemical can be calculated by using LC50 and the equation. The upper and lower 95% confidence limits for calculated TLV-TWA were TLV-TWA (calculated from LC50) 22.9 and TLV-TWA (calculated)/22.9, respectively, where LC50 for rats expressed in ppm hr was used.

A Pilot Study on the Human Body Vibration Induced by Low Frequency Noise
Yukio TAKAHASHI, Yoshiharu YONEKAWA, Kazuo KANADA and Setsuo MAEDA
Abstract : To understand the basic characteristics of the human body vibration induced by low frequency noise and to use it to evaluate the effects on health, we designed a measuring method with a miniature accelerometer and carried out preliminary measurements. Vibration was measured on the chest and abdomen of 6 male subjects who were exposed to pure tones in the frequency range of 20 to 50 Hz, where the method we designed was proved to be sensitive enough to detect vibration on the body surface. The level and rate of increase with frequency of the vibration turned out to be higher on the chest than on the abdomen. This difference was considered to be due to the mechanical structure of the human body. It also turned out that the measured noise-induced vibration negatively correlated with the subject's BMI (Body Mass Index), which suggested that the health effects of low frequency noise depended not only on the mechanical structure but also on the physical constitution of the human body.

Hexavalent Chromium Responsible for Lung Lesions Induced by Intratracheal Instillation of Chromium Fumes in Rats
Tadao TOYA, Kazuo FUKUDA, Norihiko KOHYAMA, Hiroko KYONO and Heihachiro ARITO
Abstract : Lung toxicity of chromium fumes (Cr fumes) was examined by a single intratracheal instillation into rats of 10.6 mg and 21.3 mg Cr fumes/kg body weight and by repeated (3 times) instillations of 10.8 mg and 21.7 mg Cr fumes/kg. The pathological changes were compared with those induced by single administrations of 3.2 mg and 19.2 mg Na2CO3 solution-insoluble fraction of Cr fumes (Cr-Fr)/kg and 20.8 mg commercially available chromium (III) oxide powder (Cr (III) oxide)/kg. Single and repeated administrations of Cr fumes suppressed growth rate in a dose-dependent manner, but administrations of Cr-Fr and Cr (III) oxide did not. A single administration of Cr fumes produced granulomas in the entire airways and alveoli with progressive fibrotic changes, as well as severe mobilization and destruction of macrophages and foamy cells. Those histopathological changes were aggravated by the repeated administration of Cr fumes. On the other hand, single administrations of Cr-Fr and Cr (III) oxide produced no remarkable histopathological changes. Cr fumes were found to be composed of 73.5% chromium (III) oxide and 26.5% chromium (VI) oxide. The primary particles of Cr fumes and Cr-Fr were similar, 0.02 μm in size (σg: 1.25), and Cr (III) oxide particles were 0.30 μm in size (σg: 1.53), measured by analytical electron microscopy (ATEM). Diffuse clusters of the primary particles in Cr fumes were identified as Cr (VI) oxide. The present results suggested that the lung toxicity of Cr fumes was mainly caused by these Cr (VI) oxide (CrO3) particles in Cr fumes.

A New Model Rat with Acute Bronchiolitis and Its Application to Research on the Toxicology of Inhaled Particulate Matter
Hiroko KYONO, Fumio SERITA, Tadao TOYA, Hisayo KUBOTA, Heihachiro ARITO, Masaya TAKAHASHI, Ryoko MARUYAMA, Katsunori HOMMA, Hisayoshi OHTA, Yoji YAMAUCHI, Minoru NAKAKITA, Yukio SEKI, Yoko ISHIHARA and Jun KAGAWA
Abstract : The aim of the present study was to establish a useful animal model that simulates humans sensitive to inhaled particulate matter (PM). We have developed a new rat model of acute bronchiolitis (Br) by exposuring animals to NiCl2 (Ni) aerosols for five days. Three days following the Ni exposure, the animals developed signs of tachypnea, mucous hypersecretion, and bronchiolar inflammation which seemed to progress quickly during the fourth to fifth day. They recovered from lesions after four weeks in clean air. To assess the sensitivity of the Br rats to inhaled particles, two kinds of PM of respirable size were tested with doses similar to or a little higher to the recommended threshold limit values (TLVs) for the working environment in Japan. Titanium dioxide (TiO2=Ti) was chosen as an inert and insoluble particles and vanadium pentoxide (V2OV5=V), as a representative soluble and toxic airborne material. The Br rats exposed to either Ti or V were compared the pathological changes in the lungs and the clearance of particles to those in normal control or Br rats kept in clean air. The following significant differences were observed in Br rats: 1. delayed recovery from pre-existing lesions or exacerbated inflammation, 2. reductions in deposition and clearance rate of inhaled particles with the progress of lesions. The present results suggest that Br rats are more susceptible to inhaled particles than control rats. Therefore, concentrations of particulate matter lower than the TLVs for Japan, which have no harmful effects on normal lungs, may not always be safe in the case of pre-existing lung inflammation.

Effect of Working Hours on Cardiovascular-Autonomic Nervous Functions in Engineers in an Electronics Manufacturing Company
Takeshi SASAKI, Kenji IWASAKI, Tatsuo OKA, Naomi HISANAGA, Takashi UEDA, Yukiko TAKADA and Yukio FUJIKI
Abstract : A field survey of 147 engineers (23-49 years) in an electronics manufacturing company was conducted to investigate the effect of working hours on cardiovascular-autonomic nervous functions (urinary catecholamines, heart rate variability and blood pressure). The subjects were divided into 3 groups by age: 23-29 (n=49), 30-39 (n=74) and 40-49 (n=24) year groups. Subjects in each age group were further divided into shorter (SWH) and longer (LWH) working hour subgroups according to the median of weekly working hours. In the 30-39 year group, urinary noradrenaline in the afternoon for LWH was significantly lower than that for SWH and a similar tendency was found in the LF/HF ratio of heart rate variability at rest. Because these two autonomic nervous indices are related to sympathetic nervous activity, the findings suggested that sympathetic nervous activity for LWH was lower than that for SWH in the 30-39 year group. Furthermore, there were significant relationships both between long working hours and short sleeping hours, and between short sleeping hours and high complaint rates of "drowsiness and dullness" in the morning in this age group. Summarizing these results, it appeared that long working hours might lower sympathetic nervous activity due to chronic sleep deprivation.

Biological Effects of Man-Made Mineral Fibers (I)
Qi-en WANG, Chun-hua HAN, Wei-dong WU, Hong-bing WANG, Shi-jie LIU and Norihiko KOHYAMA
Abstract : 10 types of standard mineral fiber samples (JFM fibers) were tested for their cytotoxicity in alveolar macrophages (AM) in vitro experiments, in which UICC chrysotile B was used as a positive control. The cytotoxicity included the production of superoxide anion radical and hydrogen peroxide, depletion of glutathione (GSH) and increase of intracellular free calcium. The results showed that chrysotile and most of the 10 mineral fibers could increase the production of superoxide anion and hydrogen peroxide, deplete the concentration of GSH and increase the level of free intracellular Ca2+ in AM. But all the effects of JFM fibers were lower than that induced by UICC chrysotile B. Although the cytotoxicity of JFM fibers were lower than that of asbestos, these mineral fibers should be used with highly care for workers in industries.

Differences in Heart Rate Variability between Young and Elderly Normal Men during Graded Head Up Tilt
Junichi AKATSU, Masaharu KUMASHIRO, Shinji MIYAKE, Norikuni KOMINE, Yuzo TAKAHASHI, Masahiro HASHIMOTO, Hidenori TOGAMI and Kazuhiro INOUE
Abstract : An autoregressive spectral analysis of heart rate variability (HRV) was used to analyze the differences in autonomic functions during graded head up tilt (HUT) between young and elderly men. After recording at the 0o position, the table was rotated to an upright position. The incline of the table was increased progressively to 15o, 30o and 60o. The data obtained from seven young subjects (mean age of 20.0 years) and nine elderly subjects (mean age of 63.3 years) were analyzed. The high frequency components expressed by normalized units (HFnu) were used as the parasympathetic indicators, and HFnu decreased with tilt angle in both age groups. These results suggested that parasympathetic withdrawal have an important role in adaptation to an upright posture in both age groups. However, mean HF amplitude at the 0 ° position in elderly men was not significantly different from that of young men at 60o tilt. A significant interaction effect (age group x tilt angle) was found for mean HF amplitude. The increase of the low frequency components expressed by normalized units (LFnu) and the LF-to-HF ratio in elderly subjects from 0o to 15o seemed to be larger than that in young subjects. Sympathetic activities may be sensitive to lower levels of orthostatic stress in the elderly, and the elderly workers are easily affected by a change in workload. Therefore, keeping the workload lower and constant may be recommended to avoid excessive sympathetic activation among the elderly.

Hematocrit Correlates with Blood Pressure in Young Male Office Workers
Noriko NISHIKIDO, Toshio KOBAYASHI and Hiroshi KASHIWAZAKI
Abstract : High hematocrit (Ht) level has been reported to be a correlating factor of hypertension in aged people, but has not been examined in younger generation. To investigate the association between Ht and blood pressure (BP) in healthy young workers, statistical analysis was performed for 646 male employees, using cross-sectional health-check data. Ht was positively correlated with systolic blood pressure (SBP) and with diastolic blood pressure (DBP) by Pearson's simple correlation analysis. Multiple regression analysis for SBP and DBP was conducted by stepwise procedure, using Ht, age, body mass index (BMI), and drinking and smoking habits as independent variables. It was revealed that Ht was a significant independent variable for DBP (p<0.001), as well as age and BMI, but not for SBP. These findings suggest that increased Ht is an important variable for assessing risk for cardiovascular disorders, especially diastolic hypertension, in young male office workers.

An Animal Exposure System using Ultrasonic Nebulizer that Generates Well Controlled Aerosols from Liquids
Fumio SERITA
Abstract : Various aerosol generators have been developed for animal inhalation experiments and the performance tests of measuring instruments and respirators. It has been, however, difficult to generate aerosols from an aqueous solution or suspension keeping the concentration and particle size distribution constant for a long time. Resolving such difficulties, the present study developed an animal exposure system that generates well-controlled and stable aerosols from liquids. The exposure system consists of an aerosol generator using ultrasonic nebulizer, a mixing chamber and an exposure chamber. The validity of this system was confirmed in the generation of NiCl2 and TiO2 aerosol from solution and suspension, respectively. The concentration levels of NiCl2 aerosol were kept at 3.2 mg/m3 and 0.89 mg/m3 for 5 hours with good coefficients of variation (CVs) of 2.5% and 1.7%, respectively. For TiO2 aerosol, the concentration levels of 1.59 mg/m3 and 0.90 mg/m3 were kept for 5 hours with small CVs of 1.3% and 2.0%, respectively. This exposure system could be sufficiently used for inhalation experiments with even high toxic aerosols such as NiCl2 because a momentary high concentration possibly affects results and an extremely stable concentration is required.

Evaluation of Passive Smoking by Measuring Urinary Trans, trans-muconic Acid and Exhaled Carbon Monoxide Levels
Shiho TANIGUCHI, Masato NIITSUYA, Yoko INOUE, Hiroshi KATAGIRI, Takehiro KADOWAKI and Yoshiharu AIZAWA
Abstract : No method has yet been established to evaluate the exposure to tobacco smoke in passive smoking (PS). We therefore conducted a study on the possibility that the levels of urinary trans, trans-muconic acid (MA) and the exhaled carbon monoxide (CO) could be indices of the passive exposure to tobacco smoke. The moderate correlation was observed between urinary MA levels and the number of consumed cigarettes per day in smokers. The mean urinary MA level of the PS (+) group was significantly higher than that with the PS (-) group. Among the PS (+) group, the mean MA level in the urine obtained in the afternoon was higher than that obtained in the morning. A high correlation was observed between the exhaled CO levels and the number of consumed cigarettes per day in smokers. Like the urinary MA level, the mean exhaled CO level in the PS (+) group, too, gave a significantly higher level than in the PS (-) group. Because the biological half life of MA (7.5 ± 0.85 h) was longer than that of CO (3.0 ± 0.36 h), the measurement of urinary MA level is recommended for evaluating the exposure of passive smoking. The measurement of exhaled CO levels is useful only for chain smokers and nonsmokers with PS just before measurement.

Micronucleus Test Using Cultured New Born Rat Astrocytes
Yuichi MIYAKOSHI, Yuji SUZUKI, Motoi OOIDA, Akira TAKAHASHI and Mitsuhiro TSUKUI
Abstract : Micronuclei is induced in cytoplasm as a consequence of the formation of chromosomal fragments or remaining chromosomes during cell division by the cause of clastogens or spindle poisons, and is used as an indicator of genotoxicity screening tests. There are few short-term genotoxicity screening tests using brain cells. We attempted to establish a new in vitro micronucleus test (MN test) system by use of central nervous system cells. Primary cultured astrocytes were prepared from newborn male Sprague-Dawley (SD) rats. In growth curve of astrocytes, doubling time was determined to be 31 h. In time study, the highest frequency of micronuclei was observed at 48 h, 72 h and 6 h-exposure-66 h-recovery by vincristine (VCR), mitomycin C (MMC) without metabolic activation system and cyclophosphamide (CPM) with metabolic activation system, respectively. Dose-response relationships between micronucleus frequency and concentrations of MMC, VCR and CPM were observed, respectively. It is suggested that the in vitro MN test using new born rat-astrocytes could be used as a screening test of environmental and occupational genotoxic chemicals in the central nervous system cells.

A Clearance Model of Inhaled Man-Made Fibers in Rat Lungs
Hajime HORI, Sumiyo ISHIMATSU, Takako OYABU, Hiroshi YAMATO, Yasuo MORIMOTO, Tohru TSUDA, Toshiaki HIGASHI and Isamu TANAKA
Abstract : A clearance model of inhaled man-made fibers (MMFs) was developed, and the calculated fiber numbers and dimensions were compared with the experimental ones using a glass fiber (GF), ceramic fiber (RF1) and two potassium octatitanate whiskers (PT1, TW). If the translocation rate by macrophages is constant and the effect of dissolution and disintegration can be ignored, the fiber number is expected to decrease exponentially with time. In the experimental study, however, the fiber number did not always decrease exponentially. In the case of RF1, the fiber number decreased almost exponentially and the diameter decreased linearly with the time. The clearance rate constant of GF during 3 to 6 months after the end of one-month exposure was greater than that during 1 to 3 months. On the contrary, the clearance rate constants of PT1 and TW during 1 to 6 months were greater than next six months. The diameter and the length of GF did not change significantly. The fiber length of PT1 tends to become longer with time although the diameter did not change significantly. Our theoretical model gives a satisfactory fit to these experimental results.

World Report on Industrial Health -Special Medical Examination Program Reform Proposal in Korea-
Yangho KIM, Jungsun PARK and Younghahn MOON
Abstract : We are at a time when reform in the special medical examination program in keeping with the changing times is desperately needed because the common perception of workers, employers, and medical examination facilities is "special medical examination is merely ritualistic and unproductive." Therefore, we have tried to set forth the basic structure for reforming the special medical examination program by taking a close look at the management status of the current program and analyzing its problems. The specifics of the special medical examination program reform proposal consist of three parts such as the types, health evaluation based on occupational medicine, and the interval, subject selection, items and procedure. Pre-placement medical examination and non-periodic medical examinations-as-necessary are introduced newly. Health evaluation based on occupational medicine consists of classification of health status, evaluation of work suitability, and post-examination measure. Details regarding the medical examination interval, subject selection, items and procedure were changed.

World Report on Industrial Health -The Present State and Future Prospects of Occupational Health in Bangladesh-
Md Shawkatuzzaman LASKAR, Noriaki HARADA and Harun A RASHID
Abstract : Bangladesh is a relatively young and developing country. At the present time, like in most developing countries, a clear demarcation between occupational health care and general medical care is difficult to be recognized in Bangladesh. Occupational health is a fairly new field, as the country is undergoing industrialization and occupational health activities are operated by several ministries, such as Labour, Health, Industry and Transport. Legal foundations of the occupational health-care system based on British India and Pakistani era, were adopted and amended by the Government of Bangladesh after the liberation of the country in 1971. Most of the Labour laws have been rectified by the Government of Bangladesh according to the ILO Conventions. Reconsideration of the occupational health service system avoiding duplication for the 'occupational health' component in several ministries might be helpful to achieve the successful provision of an occupational health service in the developing Bangladesh.

International Standards on Mental Work-Load --The ISO 10 075 Series--
Friedhelm NACHREINER
Abstract : After a short review of the history and an introduction into the background of standardization in the field of mental work-load an overview over the ISO 10 075 series of standards on ergonomic principles related to mental work-load is given. The review also presents relationships of these standards with some other ergonomic standards and some of the problems associated with standardization in the field of mental work-load. The stress-strain model, the concepts and the terminology used in ISO 10 075 are presented in the overview, together with the basic ideas and the frame of reference of the design guidelines provided by ISO 10 075-2. An outline of the state of discussion and possible developments of a working draft for ISO 10 075-3 on diagnostic methods concludes the presentation of the international standards on mental work-load.

Measurement of Fatigue in Industries
Friedhelm NACHREINER
Abstract : Fatigue of workers is a complex phenomenon resulting from various factors in technically innovated modern industries, and it appears as a feeling of exhaustion, lowering of physiological functions, breakdown of autonomic nervous balance, and decrease in work efficiency. On the other hand industrial fatigue is caused by excessive workload, remarkable alteration in working posture and diurnal and nocturnal rhythms in daily life. Working modes in modern industries have changed from work with the whole body into that with the hands, arms, legs and/or eyes which are parts of the body, and from physical work to mental work. Visual display terminal (VDT) work is one of the most characteristic jobs in the various kinds of workplaces. A large number of fatigue tests have already been adopted, but it is still hard to draw a generalized conclusion as to the method of selecting the most appropriate test battery for a given work load. As apparatus for fatigue measurement of VDT work we have developed VRT (Visual Reaction Test) and the Portable Fatigue Meter. Furthermore, we have presented immune parameters of peripheral blood and splenic T cells for physical fatigue.

Emotional Stress and Characteristics of Brain Noradrenaline Release in the Rat
Masatoshi TANAKA
Abstract : We have investigated several characteristics of the rat brain noradrenaline (NA) release caused by various stressful situations. Stresses such as immobilization or electric foot shock, wherein the physical factors rather than emotional ones were greatly involved, caused more marked increases in NA release in the more extended brain regions, as compared to psychological stress and conditioned fear, which caused increases in NA release preferentially in the hypothalamus, amygdala and locus coeruleus (LC) region. When the electric shock stress and psychological stress for 1 hr daily were repeated for 5 consecutive days, increases in brain NA release induced by electric shock were rapidly reduced, but those caused by psychological stress were enhanced rather than reduced. Rats with no stressor controllability (uncontrollable) had more severe gastric lesions and more marked increases in NA release in such brain regions as the hypothalamus and amygdala after 21 hrs of training than controllable rats. Rats with no opportunity to predict electric shock exhibited more severe gastric lesions and more marked increases in hypothalamic NA release than the predictable rats. The rats not allowed to express their aggression had more severe gastric mucosal lesions and a more noticeable and persistent increases in extracelluar NA content in the amygdala determined by intracerebral microdialysis than the rats allowed to express aggression by biting a wooden stick in front of them during stress exposure. In aged rats (12 months old), recovery from increases in NA release in the hypothalamus and amygdala and increases in plasma corticosterone were much later than in young (2-month-old) rats. When rats were exposed to a series of six 15-min stress interrupted by 18-min non-stress periods for 180 min, they had much greater increases in brain NA release than rats stressed continuously for 180 min. Based upon these findings, we suggest that such stresses might be harmful to our health as psychological, uncontrollable and unpredictable stresses, stress unable to express aggression, stress in elderly people, and stress with lack of suitable rest.

Occupational Stress in Human Computer Interaction
Michael J.SMITH, Frank T.CONWAY and Ben-Tzion KARSH
Abstract : There have been a variety of research approaches that have examined the stress issues related to human computer interaction including laboratory studies, cross-sectional surveys, longitudinal case studies and intervention studies. A critical review of these studies indicates that there are important physiological, biochemical, somatic and psychological indicators of stress that are related to work activities where human computer interaction occurs. Many of the stressors of human computer interaction at work are similar to those stressors that have historically been observed in other automated jobs. These include high workload, high work pressure, diminished job control, inadequate employee training to use new technology, monotonous tasks, poor supervisory relations, and fear for job security. New stressors have emerged that can be tied primarily to human computer interaction. These include technology breakdowns, technology slowdowns, and electronic performance monitoring. The effects of the stress of human computer interaction in the workplace are increased physiological arousal; somatic complaints, especially of the musculoskeletal system; mood disturbances, particularly anxiety, fear and anger; and diminished quality of working life, such as reduced job satisfaction. Interventions to reduce the stress of computer technology have included improved technology implementation approaches and increased employee participation in implementation. Recommendations for ways to reduce the stress of human computer interaction at work are presented. These include proper ergonomic conditions, increased organizational support, improved job content, proper workload to decrease work pressure, and enhanced opportunities for social support. A model approach to the design of human computer interaction at work that focuses on the system "balance" is proposed.

Epidemiology of Job Stress and Health in Japan --Review of Current Evidence and Future Direction--
Norito KAWAKAMI and Takashi HARATANI
Abstract : With the increasing concern about job stress, there is a growing body of literature addressing psychosocial job stress and its adverse effects on health in Japan. This paper reviews research findings over the past 15 years concerning the assessment of job stress, the relationship of job stress to mental and physical health, and the effects of worksite stress reduction activities in Japan. Although studies were conducted in the past using ad-hoc job stress questionnaires, well-established job stressor scales have since been translated into Japanese, their psychometric properties tested and these scales extensively used in recent epidemiologic studies. While the impact of overtime and quantitative job overload on mental health seems moderate, job control, skill use and worksite support, as well as qualitative job demands, had greater effects on psychological distress and drinking problems in cross-sectional and prospective studies. These job stressors also indicated a strong association with psychiatric disorders, including major depression, even with a prospective study design. Long working hours were associated with a higher risk of myocardial infarction, diabetes mellitus and hypertension. There is evidence that the job demands-control model, as well as the use of new technology at work, is associated with higher levels of blood pressure and serum lipids among Japanese working populations. Fibrinolytic activity, blood glucose levels, immune functions and medical consultation rates were also affected by job stressors. It is further suggested that Japanese workers tend to suppress expression of positive feelings, which results in apparently higher psychological distress and lower job satisfaction among Japanese workers compared with workers in the U.S. Future epidemiologic studies in Japan should focus more on a prospective study design, theoretical models of job stress, job stress among women, and cultural difference and well-designed intervention studies of various types of worksite stress reduction.

Ergonomic Strategies for Improving Working Conditions in Some Developing Countries in Asia
Tsuyoshi KAWAKAMI, Jose Maria BATINO and Ton That KHAI
Abstract : Ergonomic action is growing in Asia in response to increasing local needs. Recent studies in some developing countries in Asia commonly developed and applied widely-applicable measures for assessing local needs in field conditions including small enterprises and agriculture. For this purpose, carefully examining the actual workplace conditions of the local people was essential. Consequently, a number of field studies could contributed to improving the working conditions of the local people in materials handling, workstation design, work organization and work environment by using available local resources. Building on local capacity and practice, action-oriented ergonomics training has also been developing and spreading into many workplaces. Various non-expert human resources including local government units, trade unions, industrial associations and the agricultural sectors have been mobilized to act as participatory trainers in the action-oriented ergonomic training programmes. Training tools such as action checklists, good local examples and group work dynamics have been developed and applied to such training activities. Learning from local achievements and focusing on locally available resources, ergonomists have facilitated these local action processes by developing action-oriented training tools and training local trainers. It was confirmed that a number of ergonomic improvements could be formulated by the self-help initiative of the local people when participatory action tools and training were provided. Developing flexible and dynamic ergonomic research and training methods to meet the diversifying needs of the local people will continuously be important. Ergonomists' efforts to cover the wider population and workplaces need to be strengthened and accelerated.

Occupational Health Psychology: An Emerging Discipline
Steven L.SAUTER, Joseph J.HURREL Jr., Heather Roberts FOX, Lois E.TETRICK and Julian BARLING
Abstract : There is growing concern that rapidly changing patterns of work organization and employment pose risk for occupational illness and injury. In the present article, we assert that these changes create new needs and opportunities for research and practice by psychologists in the area of work organization and health. We begin with an historical overview of the contribution of psychologists to the occupational safety and health field, and to the study of work organization and health. We then describe new initiatives by the American Psychological Association and national health organizations in the United States and Europe to frame a new field of study --called "occupational health psychology"-- that focuses on the topic of work organization and health. We conclude with a discussion of emerging research needs and trends within this field.

Rapid and Simple Analysis of Urinary Vanilmandelic Acid by High-performance Liquid Chromatography with Electrochemical Detection
Takeshi SASAKI, Tatsuo OKA, Naomi HISANAGA and Kenji IWASAKI
Abstract : We examined an analytical method for urinary vanilmandelic acid (VMA) by high-performance liquid chromatography with electrochemical detection from the viewpoint of practical analysis and application. The sample pretreatment in our method is only the dilution of urine samples with citrate buffer. The calibration curve for VMA was linear within the range 0.2 to 20 ng. The detection limit was 50 pg at a signal-to-noise ratio of 3 and the coefficients of variation were 2.30-4.30%. Variations in the urinary levels of VMA, noradrenaline (NA) and adrenaline (Ad) during and after exercise were investigated for 5 males (mean ± SD, 42.4 ± 4.3 years of age). The high levels of urinary NA and Ad during 1 hr exercise rapidly decreased after exercise, whereas urinary VMA increased after exercise rather than during exercise and decreased later. The correlation of the urinary levels of VMA and NA for 71 salesman (mean ± SD, 40.6 ± 11.7 years of age) in a field study was significantly positive (r=0.426, p<0.001). These results suggest that urinary VMA mostly reflects NA, but the excretion rate of VMA is slower than that of NA.

Shift Work-Related Problems in 16-h Night Shift Nurses (1) --Development of An Automated Data Processing System for Questionnaires, Heart Rate, Physical Activity and Posture--
Hideki FUKUDA, Masaya TAKAHASHI, Keiichi MIKI, Takashi HARATANI, Lumie KURABAYASHI, Naomi HISANAGA, Heihachiro ARITO, Hideko TAKAHASHI, Makiko EGOSHI and Misuzu SAKURAI
Abstract : To assess the shift work-related problems associated with a 16-h night shift in a two-shift system, we took the following important factors into consideration; the interaction between circadian rhythms and the longer night shift, the type of morningness and eveningness experienced, the subjective sleep feeling, the subjects' daily behavior, the effectiveness of taking a nap during the long night shift, and finally the effectiveness of using several different kinds of measuring devices. Included among the measuring devices used were a standard questionnaire, repetitive self-assessment of subjective symptoms and daily behavior at short intervals, and a continuous recording of such objective indices as physical activity and heart rate. A potential problem lies in the fact that field studies that use such measures tend to produce a mass of data, and are thus faced with the accompanying technical problem of analyzing such a large amount of data (time, effort and cost). To solve the data analysis problem, we developed an automated data processing system. Through the use of an image scanner with a paper feeder, standard paper, an optical character recognition function and common application software, we were able to analyze a mass of data continuously and automatically within a short time. Our system should prove useful for field studies that produce a large amount of data collected with several different kinds of measuring devices.

Shift Work-Related Problems in 16-h Night Shift Nurses (2) --Effects on Subjective Symptoms, Physical Activity, Heart Rate, and Sleep--
Masaya TAKAHASHI, Hideki FUKUDA, Keiichi MIKI, Takashi HARATANI, Lumie KURABAYASHI, Naomi HISANAGA, Heihachiro ARITO, Hideko TAKAHASHI, Makiko EGOSHI and Misuzu SAKURAI
Abstract : We compared the shift work-related problems between 16-h night shift and 8-h evening/night shifts among nurses in a university hospital with respect to subjective symptoms, physical activity, heart rate (HR), and sleep. The nurses of one group (n=20) worked a 16-h night shift under a rotating two-shift system, while those of the other group (n=20) worked an 8-h evening or night shift under a rotating three-shift system. The 16-h night shift was staffed by three or four nurses who alternately took a 2-h nap during the shift, and had at least one day off after each shift. Subjective symptoms and daily behavior were measured every 30 min by the nurses before, during, after each shift as well as during days off using a time-budget method. Also, physical activity, heart rate (HR), and posture were recorded during shifts. The results showed similar or lower levels of sleepiness, difficulty in concentration, fatigue, physical activity, and HR during the 16-h shift compared to the 8-h shifts. No differences in subjective symptoms between the two shift schedules were observed before or after the shifts or during days off. The main sleep was longer after the shifts and during days off in the 16-h shift group than in the 8-h shift group. Our results suggest that the work-related problems in 16-h night shift nurses may not be excessively greater than those in 8-h evening/night shift nurses, as long as appropriate countermeasures are taken during and after the extended shift.

Effects of Mailed Advice on Stress Reduction among Employees in Japan --A Randomized Controlled Trial--
Norito KAWAKAMI, Takashi HARATANI, Noboru IWATA, Yuichi IMANAKA, Katsuyuki MURATA and Shunichi ARAKI
Abstract : We conducted a randomized controlled trial (RCT) to examine the effects of mailed advice on reducing psychological distress, blood pressure, serum lipids, and sick leave of workers employed in a manufacturing plant in Japan. Those who indicated higher psychological distress (defined as having GHQ scores of three or greater) in the baseline questionnaire survey (n=226) were randomly assigned to an intervention group or a control group. Individualized letters were sent to the subjects of the intervention group, informing them of their stress levels and recommending an improvement in daily habits and other behaviors to reduce stress. Eighty-one and 77 subjects in the intervention and control groups, respectively, responded to the one-year follow-up survey. No significant intervention effect was observed for the GHQ scores, blood pressure, serum lipids, or sick leave (p>0.05). The intervention effect was marginally significant for changes in regular breakfasts and daily alcohol consumption (p=0.09). The intervention effect was marginally significant for the GHQ scores among those who initially did not eat breakfast regularly (p=0.06). The study suggests that only sending mailed advice is not an effective measure for worksite stress reduction. Mailed advice which focuses on a particular subgroup (e.g., those who do not eat breakfast regularly) may be more effective.

Sickness Absence due to Mental Disorders in Japanese Workforce
Takashi MUTO, Yuko SUMIYOSHI, Susumu SAWADA, Hiroshi MOMOTANI, Ichiro ITOH, Hiroshi FUKUDA, Mitsuhide TAIRA, Shigeru KAWAGOE, Gentaro WATANABE, Hisako MINOWA and Shigeo TAKEDA
Abstract : This study was conducted to elucidate sickness absence due to mental disorders in Japanese companies. Data on sickness absence taken for seven consecutive days or more at eight companies (total number of employees: 44,816) was used for the analysis. Diagnosis of mental disorders was based on medical certificates prepared by physicians. The frequency of absence due to all diseases and mental disorders was 3.0% and 0.3%, respectively. The proportion of frequency absence due to mental disorders compared to that for all diseases was 9.4%. Figures for absence prevalence were almost the same as those for frequency absence. The average length of absence due to mental disorders and non-mental disorders was 119.5 days and 47.3 days, respectively. Rate of absence days due to mental disorders compared to that for all diseases was 21.0%. Percent of sickness absenteeism was 0.4%. In one company, the proportion of frequency absence and rate of absence days due to mental disorders compared to those for all diseases had an increasing tendency over the last six years.

Psychosomatic Symptoms of Japanese Working Women and Their Need for Stress Management
Yoko ARAKI, Takashi MUTO and Takashi ASAKURA
Abstract : This study was conducted to clarify Japanese female workers' psychosomatic symptoms including women-specific complaints and their need for stress management as part of occupational health services (OHS). In 1997, a survey was conducted in which a questionnaire was sent to 1108 full-time female workers. The response rate was 92.1%. They classified their own health status excellent (26.0%), good (60.4%), fair (9.6%), or bad (1.6%). They also reported their irritability (25.3%) and depression (15.6%). There were high rates of complaints of eye discomfort (53.6%), fatigue (44.1%), headache (43.0%), and menstrual pain (32.5%). Such symptoms were associated with irritability or depression. Amount of overtime works, marital status in the 30-44 age group, the presence of children were found to be important factors in determining health status. Regarding the needs for occupational health services, 22.2% of respondents answered they needed mental health management (MHM). Compared with other services, such as management of lifestyle diseases, gynecological diseases, cancer screenings and counseling on nutrition and exercise, the need for MHM was low. The preferred personnel were female doctors and nurses. Workers who performed frequent overtime work had a greater need for MHM. The most preferred means of receiving MHM was personal counseling by doctors (not psychologists) and nurses.

Job Stressor-Mental Health Associations in a Sample of Japanese Working Adults --Artifacts of Positive and Negative Questions?--
Noboru IWATA, Norito KAWAKAMI, Takashi HARATANI, Katsuyuki MURATA and Shunichi ARAKI
Abstract : To examine whether positive and negative components of mental health were differently related to job stressors and life events, correlational analyses were conducted using data for the GHQ-12 and some scales of the NIOSH Generic Job Stress Questionnaire collected from 765 workers in Japan. Six positive items and six negative items of the GHQ-12 were summed up for positive and negative components of mental health (GHQ-POS, GHQ-NEG). The GHQ-POS was significantly correlated with only positively-oriented job stressors. The GHQ-NEG was significantly correlated with only negatively-oriented job stressors. Most correlations were significantly different between GHQ-POS and GHQ-NEG. This correlation pattern resulted in smaller, but significant, correlations between job stressors and the GHQ-12. These results may reflect "measuring similarity" due to item-wording. Detailed inspection suggested that GHQ-POS and GHQ-NEG, as well as positively- and negatively-oriented job stressors, were not attributable only to positive affectivity or negative affectivity, respectively. Work-related events showed higher correlations with all mental health variables than their job stressors' counterparts. For females, mental health variables were seldom correlated with job stressors, but significantly correlated with life events. These results might indicate the superiority of "event-type stress measure" as compared to perceived rating scale in assessing job stressors. Further direction was discussed.

The Hazards of Chrysotile Asbestos: A Critical Review
Philip J.LANDRIGAN, William J.NICHOLSON, Yasunosuke SUZUKI and Joseph LADOU
Abstract : Chrysotile, or "white", asbestos is the dominant form of asbestos in international commerce today. It accounts for 99% of current world asbestos production of 2 million tonnes. Chrysotile is an extremely hazardous material. Clinical and epidemiologic studies have established incontrovertibly that chrysotile causes cancer of the lung, malignant mesothelioma of the pleura and peritoneum, cancer of the larynx and certain gastrointestinal cancers. Chrysotile also causes asbestosis, a progressive fibrous disease of the lungs. Risk of these diseases increases with cumulative lifetime exposure to chrysotile and rises also with increasing time interval (latency) since first exposure. Comparative analyses have established that chrysotile is 2 to 4 times less potent than crocidolite asbestos in its ability to cause malignant mesothelioma, but of equal potency of causation of lung cancer. The International Agency for Research on Cancer of the World Health Organization has declared chrysotile asbestos a proven human carcinogen. Sales of chrysotile asbestos have virtually ended in Western Europe and North America, because of widespread recognition of its health hazards. However, asbestos sales remain strong in Japan, across Asia and in developing nations worldwide. The claim has been made that chrysotile asbestos can be used "safely" under "certain conditions" in those nations. That claim is not accurate. The Collegium Ramazzini, an international learned society in environmental and occupational medicine, has called for an immediate worldwide ban on all sales and uses of all forms of asbestos, including chrysotile. The rationale for this ban is threefold: (1) that safer substitute materials are readily available, (2) that "controlled" use of asbestos is not possible, and (3) that the health risks of asbestos are not acceptable in either the industrialized or the newly industrializing nations.

Prevention of Occupational Allergy Caused by Exposure to Acid Anhydrides
Kozo YOKOTA, Tatsuya TAKESHITA and Kanehisa MORIMOTO
Abstract : This paper focuses on the prevention of IgE-mediated symptoms ofthe eyes and airways caused by exposure to acid anhydrides in the workplace. Acid anhydrides are widely used in the production of alkyd resins and as curing agents for epoxy resins. Heavy exposure to acid anhydrides causes severe irritation. However, reports of direct irritation of mucous membranes or skin are rare in recent years, since a package of multiple engineeringcontrols has been introduced to reduce exposure. On the other hand, acid anhydrides are well-known industrial inhalant sensitizers and can cause occupational allergy even at very low exposure intensities. Therefore, safe use in industry demands both control of the level of exposure causing allergic diseases in the workshop and programmes for prevention of occupational allergy.

Linearly and Circularly Polarized, 50 Hz Magnetic Fields Did Not Alter Intracellular Calcium in Rat Immune Cells
Izumi NISHIMURA, Kenichi YAMAZAKI, Tsukasa SHIGEMITSU, Tadashi NEGISHI and Takao SASANO
Abstract : This study was conducted to determine if exposure to 50 Hz magnetic field (MF) affects intracellular calcium ([Ca2+]i). We employed flow cytometry for real-time detection of possible changes in [Ca2+]i in a large number of cells. A solenoid coil for vertical MF exposure and a multiple-loop square-coil for horizontal MF were utilized. In the laboratory, background 50 Hz MF was less than 0.08 μT when all necessary equipment was powered. Rat thymocytes were exposed to 0.1 mT horizontal or vertical field, or to 0.14 mT circularly polarized field for 30 min; the effects of consecutive exposures to vertical and horizontal MFs, or vice versa, for 20 min each also were examined. In addition, intact thymocytes or lectin-activated thymocytes, splenocytes and peripheral blood lymphocytes were exposed to the 5 mT vertical field for 30 min. In all these experiments, no alteration in [Ca2+]i was evident. As a positive control, a calcium ionophore always was added to the medium following MF exposure to verify that the cells were capable of increasing [Ca2+]i and the system would record the response. The data indicate that MF exposure had no effect on [Ca2+]i under any of the conditions examined.

Silica Increases Cytosolic Calcium and Causes Cell Injury in Renal Cell Lines
Seok Ho CHA, Hye Sun KIM, Ju Young KIM, Eun-Jung LEE, Woon Kyu LEE, Hitoshi ENDOU and Young-Nam CHA
Abstract : The purpose of this study was to clarify the effect of silica-induced cytosolic free calcium mobilization and cell injury in immortalized cell lines from transgenic mice kidney harboring SV40 T-antigen gene. The proximal convoluted tubule (S1)- and the inner medullary collecting tubule (IMCT)-originated cell lines were used. Cytosolic free calcium concentration ([Ca2+]i) was measured employing Fura-2 fluorescence and cell injury was evaluated by a vital dye exclusion procedure. Silica increased [Ca2+]i in a concentration-dependent manner in S1 (60 μg/ml-600 μg/ml) and IMCT (6 μg/ml-600 μg/ml). Silica caused a biphasic increase in [Ca2+]i which was composed of an initial rapid rise and following sustained phase. Ca2+ removal from the medium resulted in abolishment of initial and sustained phase of silica (600 μg/ml)-induced [Ca2+]i in both cell lines. Silica-induced cell injury was increased in a dose-dependent manner. This silica-induced cell injury was attenuated by the pretreatment with EGTA (100 μM) and nifedipine (1 μM). Cellular ATP content ([ATP]i) by silica also decreased in a concentration-dependent manner. The relationship between [Ca2+]i and [ATP]i showed that [ATP]i depletion caused [Ca2+]i to rise. This study suggests that 1) the elevation of [Ca2+]i caused by silica is due mainly to influx through plasma membrane Ca2+ channel and non specific membrane damage (at high concentration) and 2) nephrotoxicity of silica shows site-specificity within the kidney.

A New Digestion Method for Recovery of MMMFs from Lungs
Sumiyo ISHIMATSU, Takako OYABU, Hajime HORI and Isamu TANAKA
Abstract : A new tissue digestion method is proposed to recover man-made mineral fibers (MMMFs) from lungs, which is an improved Kjeldahl method using microwaves. Tissue digestion is carried out under five different conditions in this experiment, and the most suitable condition is found as follows; dried rat lung (0.5 g of wet weight) is put into a flask with 0.1 ml of H2SO4 and 2.0 ml of HNO3, and treated by microwaves for 5 min. After the treatment, 1.0 ml of H2O2 is added immediately and the sample is treated again under the same condition. Pure samples of glass fibers and refractory ceramic fibers are treated by this proposed method. Numbers and sizes of the fibers are measured before and after the treatment on enlarged photos taking by a scanning electron microscope. As no significant changes are observed in fiber dimensions and numbers, the proposed method is shown to be applicable to recover these MMMFs from lungs.

Occupational Exposure to Lead-Granulometric Distribution of Airborne Lead in Relation to Risk Assessment-
Giovanni CARELLI, Oliviero MASCI, Augusto ALTIERI and Nicolo' CASTELLINO
Abstract : The amount of airborne lead absorbed by the body during occupational exposure depends not only on lead concentration in workplace air, but also on the granulometric distribution of the aerosol. The Occupational Safety and Health Administration (OSHA) set the lead Permissible Exposure Limit (PEL) at 50 μg/m3 on the basis of Bernard's model and a number of assumptions, including assumption "C", which predicts that the first 12.5 μg/m3 are made up of fine particles (aerodynamic diameter <1 μm) whereas the remaining 12.5 μg/m3 consist of particles >1 μm. Occupational exposure to airborne lead at a concentration of 50 μg/m3 and a granulometric distribution calculated according to the above mentioned assumption, leads, in the model, to a mean blood level of 40 μg/dl. In the present study, we tested the validity of assumption "C" in the environmental air of a factory that manufactured crystal glassware containing 24% lead oxide. An 8-stage impactor was used to measure the particle size of airborne dust collected from personal and area samplings. Results indicate that, on the whole, assumption "C" cannot be considered valid in the work environment investigated in this study. As a result, lead absorption levels in exposed workers may be noticeably different from those predicted by the OSHA model. We therefore suggest that in order to make a correct evaluation of the risk of occupational exposure to lead, it is essential to integrate total airborne lead concentration with a measurement of the granulometric distribution of the aerosol.

Environmental Measurements of Total Dust and Fiber Concentration in Manufacturer and User of Man-Made Mineral Fibers
Ji-Hong KIM, Hwang-Shin CHANG, Kang-Yoon KIM, Wha-Me PARK, Young-Ja LEE, Ho-Chun CHOI, Kyoung-Ah KIM and Young LIM
Abstract : Man-made mineral fibers (MMMF), most of which are referred to as man-made vitreous fibers (MMVF), are mostly amorphous silicates manufactured from glass, rock, or other minerals. Analysis for MMMF have been restricted largely to the measurement of total airborne mass concentrations, but more recently to the determination of airborne fiber levels by phase contrast optical microscopy. In Korea, many small factories are related with manufacturing and using MMMF without any special evaluation of environmental measurements. Though MMMF are known as the substitute of asbestos and their toxicity are regarded as very low, MMMF do not totally excluded from the respiratory and/or skin diseases now. Therefore, we evaluated the environments of many workplaces with total dust and fiber concentration. Most dust and fiber concentrations were below threshold limit value (TLV) at various industries and working processes. However, these data showed a slight relationship between total dust and fiber concentration.

Effects of Mineral Fibers on the Gene Expression of Proinflammatory Cytokines and Inducible Nitric-Oxide Synthase in Alveolar Macrophages
Yasuo MORIMOTO, Tohru TSUDA, Masami HIROHASHI, Hiroshi YAMATO, Hajime HORI, Akira OHGAMI, Kazuhiro YATERA, Heung-Nam KIM, Li DING, Masamitsu KIDO, Toshiaki HIGASHI and Isamu TANAKA
Abstract : To determine which parameters are useful for the risk assessment of man-made mineral fibers (MMMFs), we examined the gene expression of interleukin-1α (IL-1α), tumor necrosis factor α (TNFα), interleukin-6 (IL-6) and inducible nitric-oxide synthase (iNOS) in mineral fiber-exposed alveolar macrophages (AMs). Male Wistar rats were intratracheally exposed to saline or mineral fibers suspended in saline (2 mg of crocidolite, chrysotile, alumina silicate refractory fiber (RF1) or potassium octatitanate whisker (TW)). Bronchoalveolar lavage was performed 4 weeks after the fiber-instillation, and the recovered AMs were stimulated by lipopolysaccharide for 2 or 6 hours. Expression of IL-1α, TNFα, IL-6 and iNOS from AMs was observed using reverse transcription - polymerase chain reaction (RT-PCR). The levels of IL-1α and IL-6 mRNA induced by mineral fiber exposure were greatest in AMs exposed to TW, crocidolite, chrysotile and RF1 in that order. However, both gene expression of iNOS and TNFα were not elevated in both crocidolite and TW exposure, despite their high pathological potential. These data suggested that IL-1α and IL-6 may be useful indicators for the risk assessment of MMMFs.

Exposure to Hexavalent Chromium Does Not Increase 8-Hydroxydeoxyguanosine Levels in Korean Chromate Pigment Workers
Heon KIM, Soo-Hun CHO and Myung-Hee CHUNG
Abstract : This study was performed to determine whether chromium exposure increased 8-hydroxydeoxyguanosine levels in respiratory epithelial and white blood cells of chromate pigment workers. The subjects of this study were 22 chromium pigment workers and 16 controls in a chromate pigments factory. To estimate the level of exposure, hexavalent chromium concentrations in the factory air were measured. Chromium concentrations of venous blood and spot urine, and 8-hydroxydeoxyguanosine levels in DNA extracted from sputum and white blood cells were determined. Correlation coefficients were calculated between them and their statistical significance was tested. Hexavalent chromium concentration in the factory air ranged from below limit of detection to 0.5150 mg/m3. Chromium levels in blood and 8-hydroxydeoxyguanosine levels in DNA extracted from venous blood and sputum were not statistically different between the two groups. Urine chromium level was significantly higher among workers. Among the correlation coefficients between blood chromium concentration, urine chromium concentration, blood 8-OH-dG level, and sputum 8-OH-dG level, none was statistically significant for workers, controls, and total subjects. Duration of employment did not show any significant correlation with those four variables, either. These results suggest that neither the hydroxyl radical nor 8-hydroxydeoxyguanosine is formed by the reduction of hexavalent chromium, or that one or both of these is formed and then effectively removed by oxygen free radical scavengers or 8-hydroxydeoxyguanosine repair enzymes. Since increased exposure to hexavalent chromium did not result in increased 8-hydroxydeoxyguanosine levels, it is unlikely that hexavalent chromium induces lung cancer through 8-hydroxydeoxyguanosine formation.

Biological Effects of Man-Made Mineral Fibers (II) --Their Genetic Damages Examined by In Vitro Assay--
Qi-en WANG, Chun-hua HAN, Ye-peng YANG, Hong-bing WANG, Wei-dong WU, Shi-jie LIU and Norihiko KOHYAMA
Abstract : In order to study and compare genetic damage induced by 10 kinds of man-made mineral fibers (JFM fibers) in cells, human lung epithelial cells (A549) were exposed to JFM fibers and chrysotile for 1 h, then single-cell gel electrophoresis (SCGE) assay was used to detect DNA strand breaks,DNA-DNA interstrand crosslink and the ability of DNA to repair; The results showed that all 10 JFM fibers could induce DNA strand breaks, DNA-DNA interstrand crosslinks and inhibit the ability of DNA repair. When human embryolung (HEL) cells were exposed to JFM fibers and chrysotile for 24 h respectively, the chromosomal aberration was analyzed and the results showed that chrysotile and most of JFM fibers at 5.0 μg/ml induced structural chromosomal aberration, but all of these effects were lower than that of chrysotile and were different among them, suggesting that 10 types of JFM fibers had genotoxicity with different degree in vitro, but all of them were lower than that of chrysotile.

Impact of Acute and Subchronic Asbestos Exposure on Some Parameters of Antioxidant Defense System and Lung Tissue Injury
Alzbeta KAIGLOVA', Zuzana KOVA'CIKOVA' and Marta HURBA'NKOVA'
Abstract : Asbestos fibers have been used in industry for decades. Deleterious effect of asbestos on the lungs has been documented. However, the mechanism of asbestos related diseases has not been fully explained yet. Numerous papers suggest there is a role of reactive oxygen intermediates (ROI) in asbestos-induced lung disease development. The excess ROI produced can be removed from the lungs by enzymatic and nonenzymatic antioxidants. The aim of our study was to compare the levels of antioxidants (ascorbic acid, retinol, α-tocopherol, glutathionperoxidase) as well as some markers of lung injury (lipid peroxides, total amount of protein, alkaline phosphatase) in asbestos treated Wistar-rats both 24 hr and 3 months after exposure to those in the controls, and to find out if the changes in antioxidant levels could affect impairment of the lungs. Decreased levels of antioxidants and increased values of lung tissue injury parameters in exposed groups suggest involvement of ROI in the mechanism of asbestos lung disease development, resulting in lung tissue injury, both 24 hr and 3 months after exposure.

Pulmonary Clearance and Lesions in Rats after a Single Inhalation of Ultrafine Metallic Nickel at Dose Levels Comparable to the Threshold Limit Value
Fumio SERITA, Hiroko KYONO and Yukio SEKI
Abstract : This study aimed to (1) determine the deposition and clearance rates of ultrafine metallic nickel (Uf-Ni) in rats after a 5 hours single inhalation exposure, and (2) to histopathologically examine the pulmonary lesions induced at dose levels comparable to the Occupational Exposure Limit recommended in Japan (OEL). The exposure concentrations of Uf-Ni for the 3 groups were 0.15 (Low), 1.14 (Medium), and 2.54 (High) mg/m3. Five rats/group were sacrificed at 0h and 1, 3, 7, 14, and 21 days post exposure. The amount of Ni in the lung accumulated dose-dependently. The half-times for Ni in the lung were estimated as 32 days on average, and were similar to each otherregardless of the initial dosage. The histopathologically observed pulmonary lesions induced by a single inhalation of Uf-Ni were, (1) a significant increase in lung weight in the High and Medium groups with time, (2) accumulation of foamy alveolar macrophages (AM), (3) degenerated AM indicating alveolar lipoproteinosis which was aggravated for up to 4 weeks in the High group and (4) acute calcification of the degenerated AM was remarkable. The present results suggest that even a single inhalation of Uf-Ni induces potency of lung lesions at dose levels comparable to the OEL (1 mg/m3 as Ni), or the TWA of ACGIH (1.5 mg/m3 for elemental/metal).

Determination of Methyltetrahydrophthalic Anhydride in Air Using Gas Chromatography with Electron-Capture Detection
Yasushi JOHYAMA, Kozo YOKOTA, Yukio FUJIKI,Tatsuya TAKESHITA and Kanehisa MORIMOTO
Abstract : Methyltetrahydrophthalic anhydride (MTHPA) stimulates the production of specific IgE antibodies which can cause occupational allergy even at extremely low levels of exposure (15-22 μg/m3). Safe use in industry demands control of the levels of exposure causing allergic diseases. Thus, the air monitoring of MTHPA is very important, and sensitive methods are required to measure low air concentrations or short-time peak exposures. This paper outlines the use of silica-gel tubes for sampling airborne MTHPA vapour, followed by analysis using gas chromatography with electron-capture detection. No breakthrough was observed at 113, 217, 673 and 830 μg/m3 (sampling volume 30, 60, 60 and 20 l, respectively; relative humidity 40-55%). Concentrations > 1.0 μg/m3 could be quantified at 20-min sampling with a sampling rate of 1 l/min. The present method can also be applied to measurements of exposure to hexahydrophthalic and methylhexahydrophthalic anhydride. The risk of MTHPA exposure in two condenser plants was also assessed by determining MTHPA levels in air of the workplace. In conclusion, our method was found to be reliable and sensitive, and can be applied to the evaluation of MTHPA exposure.

The Effect of a Tilting Seat on Back, Lower Back and Legs during Sitting Work
Hiroshi UDO, Masahiko FUJIMURA and Fumitaka YOSHINAGA
Abstract : The purpose of this study was to examine the possible effects of a tilting seat on the back, lower back and legs. Ten healthy male subjects aged 22-28 performed word-processing operations while sitting on a chair for one hour under two different seating conditions: the rocking condition and the fixed condition. While the subjects were performing the task, measurements of lower leg swelling were taken using bioelectrical impedance plethysmography, and pain scores were recorded every five min for the neck, shoulders, back, lower back, hips and legs. Electromyograms (EMGs) of the back and lower back (at Th5-6, Th8-9, L1-2 and L3-4) were recorded every sec. In addition, the subjects were videotaped while using the rocking seat, in order to analyze the angle and frequency of seat tilting. At the end of the experiment, the subjects were asked to evaluate the two conditions with respect to localized fatigue and operational efficiency. There was no significant difference in lower leg swelling between the two conditions. EMGs were significantly different at Th5-6, Th8-9 and L1-2 between the two conditions. The rocking condition generated greater EMGs at Th5-6 and L1-2, whereas the fixed condition produced greater EMGs at Th8-9. The pain scores for the neck, shoulders, back and lower back were higher under the fixed condition, while those for the buttocks were higher under the rocking condition. The average tilting frequency was as low as 25.2 times per hour, with 15.6 times per hour for tilting angles ranging from 1 to 2 degrees, and 9.6 times per hour for tilting angles exceeding 2 degrees. As for the subjective evaluations of localized fatigue, seven of the ten subjects preferred the rocking condition, while two preferred the fixed condition and one subject had no preference. Thus, there was a significant difference in the subjective evaluations of the twochairs. These findings suggest that the rocking condition, in contrast to the fixed seating condition, reduced back and lower back pain as a result of its tilting capability. The results of EMGs suggest that the rocking condition reduced back and lower back pain by increasing the overall muscle activity of the back and lower back. The leg impedance measurements showed no effect of the rocking condition on the leg swelling, as compared with the fixed condition.

Heart Rate Variability in Response to Psychological Test in Hand-Arm Vibration Syndrome Patients Assessed by Frequency Domain Analysis
Md Shawkatuzzaman LASKAR, Mieko IWAMOTO, Norikuni TOIBANA, Takako MORIE, Tadaaki WAKUI and Noriaki HARADA
Abstract : To investigate heart rate variability in response to psychological tests (Japanese version of Stroop color word test and mirror drawing test) in 29 hand-arm vibration syndrome (HAVS) patients, 16 of them with vibration-induced white finger (VWF) and 13 without VWF, and 10 healthy controls of similar age, heart rate variability during spontaneous and deep (6 cycles a minute) breathing in supine position before and after exposure to the psychological tests was examined calculating frequency domain components such as low frequency (LF) power-index of both the sympathetic and parasympathetic activity, high frequency (HF) power-index of the parasympathetic activity and LF/HF-index of the sympathovagal balance. The group of all patients and thegroup without VWF indicated significant increase in LF/HF in the deep breathing measurement after exposure to the psychological tests. The result suggests that the sympathetic tone in the sympathovagal balance predominated in the HAVS patients which means that they had larger sensitivity of the sympathetic nervous system to the psychological tests.

Lumbar Vertebral Angles and Back Muscle Loading with Belts
Yung-Hui LEE and Chih-Yong CHEN
Abstract : The study examined belt effects on the change of lumbosacral angle (LSA) and back muscle activity in postures of standing, erect sitting, and slump sitting. We thought that the resulting changes of LSA and back muscle activity when wearing belts with different mechanical characteristics should be different. Eighteen healthy male subjects participated in this study. Though we failed to identify a significant belt effect on the back muscle EMG, the radiographic data revealed an interactive effect of postures and belts on the change of LSA. In standing, the belts increased LSA by increasing almost every lumbar vertebral angle. In erect sitting, the lumbar belt had no effect but the pelvic belt decreased LSA through a decrease in the L1/L3. While sitting slump with a trunk flexion of 15 degrees, both belts increased LSA by restricting the movement of the pelvis. Belt effect on LSA was accompanied with a change of pelvic angle. Significant correlation was found between the backward rotation angles of the pelvis and the angles of LSA (r=0.692, p<0.0001), also between the decrease of pelvic angles and the increase of back muscle EMG (r=-0.4, p=0.017). A change in LSA and pelvic angle after wearing a belt along with posture change seems lead to an increase of the myoelectric activities on the back.

Whole-Body Vibration Perception Thresholds of Recumbent Subjects --Part 1: Supine Posture--
Yoshiharu YONEKAWA, Setsuo MAEDA, Kazuo KANADA and Yukio TAKAHASHI
Abstract : The objective of the present study was to determine perception thresholds for whole-body vibration in the recumbent supine posture in vertical and horizontal directions and to compare the present results with ones obtained at the same laboratory in 1984 and also with ISO frequency weighting curves both in ISO 2631-1 and in ISO 2631-2. The frequency characteristic and thresholds values of the present results are similar to previous results. Weighting curves of ISO, however, show quite different characteristic in both vertical and horizontal directions compared to the present characteristics. It is not suitable to apply weighting curves Wk for the vertical direction, Wd for the horizontal direction and combined curves in ISO to recumbent posture from the results of this present study.

Whole-Body Vibration Perception Thresholds of Recumbent Subjects --Part 2: Effect of Vibration Direction--
Setsuo MAEDA, Yoshiharu YONEKAWA, Kazuo KANADA and Yukio TAKAHASHI
Abstract : This paper presents the results of laboratory experiment concerned with perception thresholds for whole-body vibration on recumbent subjects. Thresholds of subjects exposed to x-, y- and z-axis sinusoidal vibration were determined for supine, prone, lying on the left side and lying on the right side subjects (from 1 to 80 Hz). It was clear that the threshold curves, as a function of frequency, had different characteristics for vertical vibrations than for horizontal vibrations in the recumbent postures. Significant differences were found between perception thresholds for vertical vibrations and horizontal vibrations on recumbent subjects.

A Four-Year Follow-Up Study on Subjective Symptoms and Functional Capacities in Workers Using Hand-Held Grinders
Seyed Mohammad MIRBOD, Farhang AKBAR-KHANZADEH, Minoru ONOZUKA, Marjan JAMALI, Kazuko WATANABE, Riyoichi INABA and Hirotoshi IWATA
Abstract : Fifty-three grinders in the metal industry were re-examined 4 years after their first examination. Information about age, occupation, daily vibration exposure, drinking and smoking habits, and presence of subjective symptoms such as vibration-induced white finger (VWF), and numbness and pain in the fingers was collected during the first and second examination. Cold provocation test (10oC/10 min) was also employed to evaluate disturbances in the peripheral circulatory and peripheral nerves in all subjects. The frequency-weighted vibration acceleration of various types of hand-held tools was measured. There was no subject with VWF at the first examination; however, during the course of follow-up, two cases (3.8%) of VWF with latent interval of more than 25 years were diagnosed. Prevalence of numbness in the fingers and shoulder stiffness was significantly higher at the second examination. When the prevalence of subjective symptoms was tested by the subjects' total operating time (TOT) during the 4-year follow-up period, those whose TOT was equal to or more than 2500 hours showed higher prevalence compared to the other subgroup. The paired values of recovery rate of finger skin temperature and vibration sensation threshold after the cold water immersion test were significantly different at the first and second examination. On average, the diminution of hand-grip force during the 4-year follow-up course was 7.4%; the difference being significant at 0.01 level. Significant differences in the paired data of pinching power and tapping ability could be detected. The frequency-weighted vibration acceleration of various tools was in the range of 1.1-4.6 m/s2. t was concluded that: (1) prolonged occupational exposure to the vibration of hand-held grinding tools should be considered as a risk factor causing disturbances in the hand-arm system of the operators; (2) the results of recovery rate of finger skin temperature and the vibration sensation threshold seemed to be appropriate indicators for the assessment of peripheral vascular and peripheral nerve disturbances in workers exposed to hand-arm vibration; and (3) to reduce the subjects' physical stress, attention should be paid to ergonomic factors.

A Study on the Effects of Countermeasures for Vibrating Tool Workers Using an Impact Wrench
Yoko AIBA, Satoshi OHSHIBA, Hisayoshi ISHIZUKA, Kunihiro SAKAMOTO, Ikuharu MORIOKA, Kazuhisa MIYASHITA and Hirotoshi IWATA
Abstract : The aims of this study were (1) to measure frequency-weighted vibration acceleration and (2) to study the effects of introducing a vibration-proof impact wrench on VWF in workers. The subject pool was 383 male workers who were regularly using an impact wrench and taking special medical examinations for vibration syndrome in a factory from 1982 to 1999. The prevalence of workers with VWF increased gradually after 1982, reached a peak value (4.8%) in 1986, gradually decreased after 1987, and disappeared in 1994. Sixteen subjects who had had VWF at least one time during the observation period were selected for this study. The stages of VWF were at stage I on the Stockholm Workshop scale in all subjects. After the vibration-proof impact wrench was introduced in 1986, the vibration acceleration of the impact wrench measured on the handle decreased from 8.6-11.1 m/s2 to 5.1-7.1 m/s2. The actual time per day that subjects were assumed to use the impact wrench was 108 minutes. The subjects actually used an impact wrench more than the occupational exposure limit allowed. However, VWF disappeared after the introduction of a vibration-proof impact wrench. This might have resulted from the combined effect of introducing the vibration-proof impact wrench and certain countermeasures that were taken against cold working environments.

Clinical, Pathological and Mineralogical Features in Two Autopsy Cases of Workers Exposed to Agalmatolite Dust
Takumi KISHIMOTO, Hidenori YAMAMOTO, Kenji MORINAGA, Yasuhiro YAMAWAKI,Takayuki YOSHIMOTO, Tomoyoshi MIYASHITA, Norihiko KOHYAMA and Yasushi SHINOHARA
Abstract : An agalmatolite miner and processor showed large shadows at the bilateral hila accompanied by surrounding emphysematous changes and irregular shadows on chest X-ray films. Chest CT scans were characterized by a mixture of tiny irregular structures and small round opacities. Histopathological examination revealed massive fibrosis, which corresponded to large shadows, but only a small number of typical silicotic nodules, indicating mixed dust pneumoconiosis. Mineralogical examination of the autopsy lungs showed quartz, pyrophyllite, mica, and kaolinite. Quartz accounted for 70% of the amount of all mineral dust in both patients, but pyrophyllite accounted for 10.8% and 14.4%. The pulmonary mineral dust composition in the two patients was well consistent with the mineral composition of the raw clays in the agalmatolite mine. In the two patients, chest X-ray findings and histopathological findings of the lungs also suggested agalmatolite pneumoconiosis, which was confirmed by mineral analysis of the lungs.

Different Change Patterns of the Isozymes of Cytochrome P450 and Glutathione S-Transferases in Chemically Induced Liver Damage in Rat
Rui-Sheng WANG, Tamie NAKAJIMA and Takeshi HONMA
Abstract : In this experiment, we studied the different changes in activities and protein levels of each subform of hepatic cytochrome P450 and glutathione S-transferase (GST), in chemical-induced liver injury in rats. Rats were administered 1,1-dichloroethylene (DCE), allyl alcohol (AA), bromobenzene (BB) and N,N-dimethylformamide (DMF) p.o. once every two days for 7 times, and decapitated 18 hr after the last administration. DCE and AA showed stronger hepatic toxicity than BB and DMF, as serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were higher in DCE and AA treated rats than in BB and DMF groups. Anti-cytochrome P450 inhibitable activity of toluene metabolism and/or immunoblot analysis showed that CYP2E1 and CYP2B1/2 were induced by BB and DMF, but not by the other two chemicals; CYP2C11 was greatly decreased by all of the four toxicants; and CYP1A1/2 was slightly reduced by the four treatments. These changes were reflected in testosterone metabolism. Formation of 6β- and 7α-hydroxytestosterone from testosterone was enhanced only in DMF-treated rats, whereas that of 2α- and 16α-hydroxytestosterone was reduced by all of the four chemicals. Serum GST activity was increased only in BB and DMF treated rats, but liver cytosolic GST activity was enhanced by all of the four hepatotoxicants, with higher values in BB and DMF groups than in DCE and AA groups. Immunoblot analysis demonstrated that GST Yp was induced by BB and DMF treatments, and Ya and Yc were increased only by BB. GST Yk and Yb1 were not affected by the treatments. The different change patterns of enzymes by a specific toxin and the similar modifying effect on a specific enzyme by different toxins were discussed in relation to the liver damage and to the heterogeneous distribution of enzymes in liver.

Association between Musculoskeletal Pain in Japanese Construction Workers and Job, Age, Alcohol Consumption, and Smoking
Satoru UENO, Naomi HISANAGA, Hiroshi JONAI, Eiji SHIBATA and Michihiro KAMIJIMA
Abstract : A cross-sectional epidemiologic study was conducted to determine the prevalence of self-reported musculoskeletal pain (MSP) in construction workers and identify associations between MSP and individual factors (i.e., job, age, alcohol consumption, and smoking). The prevalence of total hand/arm pain (T-HAP), total shoulder pain (T-SP), and total low-back pain (T-LBP) was 28.4%, 28.7%, and 53.2%, respectively. Risk factors for total pain and for relatively severe pain in the hand/arm (RS-HAP), shoulder (RS-SP), and low-back (RS-LBP) were estimated by multiple logistic regression analysis. The results showed that musculoskeletal pain was significantly associated with age, and that the odds ratios (ORs) for relatively severe musculoskeletal pain increased almost linearly with age. Regarding job, compared with architects whose work is presumed to be sedentary, almost all ORs for T-HAP, T-SP, and T-LBP for non-sedentary construction jobs were significantly high. Current smokers of 20 cigarettes a day or more had significantly higher ORs for RS-HAP and RS-LBP than "never smokers". We suppose that 1) total and relatively severe pain were associated with age, 2) non-sedentary work was at higher risk of total MSP than sedentary work, and 3) heavy smoking contributed to RS-LBP.

Association of Working Hours with Biological Indices Related to the Cardiovascular System among Engineers in a Machinery Manufacturing Company
Takeshi SASAKI, Kenji IWASAKI, Tatsuo OKA and Naomi HISANAGA
Abstract : A field survey of 278 engineers (20-59 years) in a machinery manufacturing company was conducted to investigate the association of working hours with biological indices related to the cardiovascular system (heart rate variability, blood pressure and serum levels of magnesium, dehydroepiandroster one sulfate and cholesterol). Average working hours (defined as <"hours at workplace" + "half a commuting time">) and sleeping hours in this study were 60.2 ± 6.3 hr/week and 6.6 ± 0.8 hr/day respectively. There were no significant relationships between working hours and biological indices related to the cardiovascular system, but sleeping hours was closely related to working hours negatively. Furthermore, the serum DHEA-S level was significantly related to sleeping hours positively. Combining these two results, it appeared that long working hours might lower the serum DHEA-S level due to the reduction of sleeping hours.

An Evaluation of Radio Frequency Exposure from Therapeutic Diathermy Equipment
Chung-Yi LI and Chao-Kang FENG
Abstract : To assess the physiotherapist's exposure to radio frequency electromagnetic fields (RF) leaking from short wave diathermy equipment, we conducted on-site measurements of stray electric and magnetic fields (27.12 MHz) close to continuous wave (CW) short wave equipment. The results show that the operator's knees may have the highest exposure level for both electric field (E-field) and magnetic field (H-field) in the normal operating position, i.e., behind the device console. The whole-body E-field exposure normally does not exceed the 1992 IEEE recommended limit during a normal treatment session. On the other hand, the operator's whole-body exposure to H-field was barely below the recommended limit. Our data suggest little chance of immediate harmful effects of RF leakage from the diathermy. Nonetheless, physiotherapists should still be advised to remain at a distance of at least 20 cm from the electrodes and cables to avoid possible overexposure.

Assessment of Workers' Exposure to Aromatic Hydrocarbons in a Paint Industry
Parvin NASSIRI and Farideh GOLBABAI
Abstract : A factory survey was conducted in a paint industry in Tehran-Iran. The time-weighted average of toluene and xylene concentration in breathing zone and environmental air were monitored by charcoal tube samplers and GC-FID. The results showed that the tank cleaners had the highest exposure to toluene and xylene (1.5f - 5.4 times of TLV), while the workers in packaging workshops had the lowest. However, environmental concentration did not show significant differences in workshops and their levels were all lower than the TLV.