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.

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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.

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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 180min, they had much greater increases in brain NA release than rats stressed continuously for 180min. 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.

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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.

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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.

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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.

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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.

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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 20ng. The detection limit was 50pg 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 1hr 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.

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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.

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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.

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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.

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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.

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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.

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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.

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