[The history of compensation system for workers with pneumoconiosis-related lung cancer].

OBJECTIVE: To review the historical aspects of compensation system for workers with pneumoconiosis who developed lung cancer. METHODS: Materials and papers published on the compensation system as discussed in administrative meetings were utilized. RESULTS: Legal claims for compensation for lung cancer among individuals with pneumoconiosis increased during the period of rapid economic growth in Japan. A possible causal relationship between pneumoconiosis and lung cancer in workers has been discussed by committees of specialists. The Expert Committee on Pneumoconiosis and Lung Cancer in 1978 did not find a causal relationship between them. However, a survey of physicians specializing in pneumoconiosis revealed medical disadvantages among individuals diagnosed with pneumoconiosis who developed lung cancer. The Ministry of Labour announced the risk of work-related lung cancer in patients with advanced pneumoconiosis (class IV or equivalent severity). Since then, numerous lung cancer patients with pneumoconiosis have been adjudicated. In 1997, the International Agency for Research on Cancer (IARC) re-evaluated the carcinogenicity of silica and declared it to be a Group I carcinogen in humans. The Expert Committee on Compensation of Lung Cancer Cases Developing from Pneumoconiosis discussed the IARC evaluation but did not accept this classification. However, the Committee of Occupational Exposure Limits in the Japan Society of Occupational Health upheld the IARC evaluation of silica as a Group I carcinogen. Because the Expert Committee of Medical Disadvantage of Lung Cancer Patients with Pneumoconiosis accepted the increased risk of lung cancer in patients with class III or equivalent severity pneumoconiosis, the Ministry of Labour announced worker compensation for such patients. The Expert Committee of Health Control of Pneumoconiosis Complicated with Lung Cancer reported in 2002 that a meta-analysis revealed no increased risk of lung cancer among workers exposed to crystalline silica; however, there was an increased risk of lung cancer in patients with pneumoconiosis. The Ministry of Labour has added lung cancer to the list of complications from pneumoconiosis and, if necessary, regular medical checkups for lung cancer. After Leaving dust work, the Health Care System provides for workers who are diagnosed With class II or higher pneumoconiosis. Therefore, if an individual with pneumoconiosis develops class II or higher lung cancer, that individual becomes eligible for workers' compensation. CONCLUSIONS: The conclusion of the Expert Committee in 2002 and the decision of the Ministry of Labour to add lung cancer to its list of complications of pneumoconiosis are evaluated to be appropriate.

Evaluation of personal exposure of workers to indium concentrations in total dust and its respirable fraction at three Japanese indium plants.

This study aimed to evaluate personal exposures of 27 workers to indium compounds as "total" dust and its "respirable" fraction in their breathing zones at 3 Japanese indium plants. Eight-hour time-weighted average (TWA) indium concentrations of personal exposure to dust collected in sampling periods of 6 h or longer were determined by ICP-MS. The arithmetic means of exposure concentrations were 0.095 mg indium (In)/m3, when sampled as total dust, and 0.059 mg In/m3, as respirable fraction. ACGIH's TLV-TWA of 0.1 mg In/m3 for total particulate matter and Acceptable Exposure Concentration Limit (AECL) of 3×10-4 mg In/m3 for the respirable fraction notified by the Japanese Ministry of Health, Labour and Welfare were used to evaluate the exposure concentrations. Twenty-five out of 27 workers were exposed to indium concentrations lower than TLV-TWA, while all of the workers were exposed to the indium concentrations higher than AECL. We noted that there was a large discrepancy between the two occupational exposure limits referred to in this report, and these differences were attributed to the sampling strategies and health effects used as the prevention targets. Carcinogenicity of the respirable fraction of indium-containing particulates was considered in setting AECL, whereas it was not in ACGIH's TLV.

Potential role of mitochondrial damage and S9 mixture including metabolic enzymes in ZnO nanoparticles-induced oxidative stress and genotoxicity in Chinese hamster lung (CHL/IU) cells.

The present study was designed to examine genotoxicity induced by 10-40 nm zinc oxide (ZnO) nanoparticles using the in vitro system. The frequency of micronuclei was significantly increased in a dose-dependent manner when cultured Chinese hamster lung (CHL/IU) cells were exposed to ZnO nanoparticles for 24, 48 and 72 h in the continuous treatment method. The maximal frequency of micronuclei was observed in exposure of CHL/IU cells to ZnO nanoparticles at a concentration of 125 µM. The frequency of micronuclei was profoundly enhanced when CHL/IU cells were exposed to ZnO nanoparticles in the presence vs. absence of S9 mixture including metabolic enzymes in the short-term treatment method, demonstrating an increase in the formation of micronuclei by S9 mixture. The maximal frequency of micronuclei was seen in exposure of CHL/IU cells to ZnO nanoparticles at a concentration of 140 µM. Similar results were obtained in chromosome aberrations, particularly structural aberrations. Surprisingly, administration of the superoxide radical scavenger, tempol, completely abolished an increase in the frequency of micronuclei in the presence or absence of S9 mixture, indicating a central role of superoxide radical in the formation of micronuclei. Indeed, reactive oxygen species (ROS) generation was elevated by simultaneous incubation of S9 mixture and ZnO nanoparticles and by exposure of CHL/IU cells to ZnO nanoparticles in the presence or absence of S9 mixture. An electron microscopic examination revealed mitochondrial damage in CHL/IU cells exposed to ZnO nanoparticles, indicating the participation of mitochondrial dysfunction in ROS generation in this setting. These observations suggest that ZnO nanoparticles evoke genotoxicity through superoxide radical-induced oxidative stress derived from mitochondrial damage in CHL/IU cells. S9 mixture appears to contribute to a further increase in genotoxicity through the generation of superoxide radical by metabolic activation of ZnO nanoparticles.

Quantitative assessment of occupational exposure to total indium dust in Japanese indium plants.

This study quantitatively assessed personal exposure of 86 workers to indium compounds as total dust at 11 Japanese indium plants. The personal exposures to indium concentrations in the breathing zone during an 8 h work-shift were determined by ICP-MS. The arithmetic mean indium concentration of all the workers was 0.098 mg Indium (In)/m3, with individual values ranging from 0.0001 to 1.421 mg In/m3. There were 11 workers whose exposure to indium concentrations exceeded the American Conference of Governmental Industrial Hygienists' Threshold Limit Value-Time Weighted Average (TLV-TWA) of 0.1 mg In/m3. Based on the condition TLV-TWA

Control banding assessment of workers' exposure to indium and its compounds in 13 Japanese indium plants.

OBJECTIVES: This study aimed to assess workers' exposure to indium and its compounds in 55 indium-handling operations among 13 Japanese plants. The surveyed plants were selected from indium-manufacturing plants whose annual indium production exceeded 500 kg. METHODS: The Control of Substances Hazardous to Health (COSHH) Essentials control banding toolkit, which contains simple scales for hazard levels, quantities in daily use, and "dustiness" characteristics, was used to assess generic risks of indium-handling operations. The operations were then classified into one of four Control Approaches (CAs). RESULTS: There were 35 indium-handling operations classified into CA4 (requires expert advice) and 16 grouped into CA3 (requires containment). There were three operations classified into CA2 (requires engineering controls) and only one into CA1 (requires good general ventilation (GV) and working practices). Of the 51 operations classified as CA4 and CA3, 36 were found to be improperly equipped with local exhaust ventilation, and the remaining 15 operations solely relied on GV practices. Respiratory protective equipment (RPE) used in the 13 indium plants was examined with reference to the recommendations of the COSHH Essentials and Japan's Technical Guidelines. CONCLUSIONS: Our findings suggest that stringent engineering control measures and respiratory protection from indium dust are needed to improve indium-handling operations. Our results show that the most common control approach for Japanese indium-handling operations is to require expert advice, including worker health checks for respiratory diseases and exposure measurement by air sampling.

Development of a method for monitoring personal exposure to benzyl violet 4B and direct blue 15 in workplace air.

OBJECTIVES: The purpose of this research was to develop a method for monitoring personal exposure to benzyl violet 4B (BV) and direct blue 15 (DB) in workplace air for risk assessment. METHODS: We evaluated the utility of the proposed method by examining the following: recovery; method limit of quantification; reproducibility; and storage stability of the samples. RESULTS: An air sampling cassette containing a glass fiber filter was chosen as the sampler. BV and DB were extracted from the sampler filters with a solution of water and methanol (7:3, v/v) and then analyzed by a high-performance liquid chromatograph equipped with a photo-diode array detector. The overall recoveries from spiked samplers were 94-102% and 94-99% for BV and DB, respectively. The recovery after seven days of storage at 4°C exceeded 95%. The method limits of quantification were 0.250 and 1.25 µg/sample for BV and DB, respectively. The relative standard deviations, which represent the overall reproducibility defined as precision, were 0.6-4.1% and 0.8-2.9% for BV and DB, respectively. CONCLUSIONS: The proposed method enables 4 h personal exposure monitoring of BV and DB at concentrations of 1-2,000 µg/m3 for BV and 5-2,000 µg/m3 for DB, with a 240 l sampling. Thus, the proposed method is useful for estimating worker exposure to BV and DB.

Assessment of workplace air concentrations of formaldehyde during and before working hours in medical facilities.

Workplace air concentrations of formaldehyde (FA) in medical facilities where FA and FA-treated organs were stored and handled were measured before and during working hours and assessed by the official method specified by Work Environment Measurement Law. Sixty-percent of the total facilities examined were judged as inappropriately controlled work environment. The concentrations of FA before working hours by spot sampling were found to exceed 0.1 ppm in some facilities, and tended to increase with increasing volume of containers storing FA and FA-treated materials. Regression analysis revealed that logarithmic concentrations of FA during working hours by the Law-specified analytical method were highly correlated with those before working hours by spot sampling, suggesting the importance for appropriate storing methods of FA and FA-treated materials. The concentrations of FA during working hours are considered to be lowered by effective ventilation of FA-contaminated workplace air and appropriate storage of FA and FA-treated materials in plastic containers in the medical facilities. In particular, such improvement by a local exhaust ventilation system and tightly-sealed containment of FA-treated material were urgently needed for the dissecting room where FA-treated cadavers were prepared and handled for a gross anatomy course in a medical school.

[A survey on the use of respirators among dust workers in outdoor working environments].

OBJECTIVES: The aim of this survey was to clarify the current status of the use of respirators among dust workers in outdoor working environments. METHODS: The participants were 38 male workers exposed to dust, who were engaged in arc welding or quarrying in outdoor working environments. We interviewed participants about wearing and storage of respirators on site. The participants were asked 9 questions about the selection, use, fitness, maintenance, storage, and instruction in the use of respirators. RESULTS: The results of this study show that all participants wore the approved dust respirators, even though it is not legally necessary to wear a respirator in outdoor working environments. Instruction about the use of respirators was found to be effective regarding inspection of the valve and headband, the fitness between the facepiece and face, the time of wearing, and storage place. However, the interviews revealed that there was insufficient knowledge about the reasons for and frequency of filter replacement. Compared to our preliminary study, the use of a knitcover decreased from 73% to 21%. CONCLUSIONS: These findings suggest that workers should be given better information on the selection, use, maintenance, and storage place of respirators to protect workers against dust exposure.

Tempol suppresses micronuclei formation in astrocytes of newborn rats exposed to 50-Hz, 10-mT electromagnetic fields under bleomycin administration.

A number of epidemiological studies have suggested that exposure to environmental and occupational electromagnetic fields (EMFs) contribute to the induction of brain tumors. The aim of this study was to investigate the mutagenetic effects of co-exposure to 50-Hz, 10-mT EMFs and bleomycin (BLM) using an ex vivo newborn rat astrocyte micronucleus assay. We also investigated whether the mutagenetic effects of EMFs were related to active oxygen species by using 4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl (tempol), a superoxide radical scavenger. Three-day-old male Sprague-Dawley rats were co-exposed to 50-Hz EMFs and BLM (5 or 10mg/kg body weight (BW)) in each group (n=6; total 6 group), and were co-exposed to 50-Hz EMFs and 10mg/kg BW BLM with administration of 200µmol/kg BW tempol in each group (total 4 group). Brain cells were dissociated into single cells, cultured for 96h, incubated with an antibody against glial fibrillary acidic protein, and stained with acridine orange. The frequency of micronucleated astrocytes was determined using a fluorescence microscope. The frequency of micronucleated astrocytes in the 10mg/kg BW bleomycin plus EMF exposure group (Mean±SD: 19.8±5.2‰) was 1.6 times higher than that in the 10mg/kg BW bleomycin plus sham-exposure group (Mean±SD: 12.7±3.3‰) (p<0.05). Analysis of the frequency of micronuclei in astrocytes after co-exposure to EMF and bleomycin for 72h and administration of tempol revealed that, in the EMF exposure group, the frequency of micronuclei in rats administered with 10mg/kg BW bleomycin and treated with tempol (Mean±SD: 11.2±1.9‰) was 40% of that in rats administered with the same dose of bleomycin and physiological saline (Mean±SD: 28.0±15.0‰) (p<0.01). Results of the current study suggested that the mechanism responsible for the elevated frequency of micronuclei in astrocytes of rats co-exposed to BLM and EMFs is related to active oxygen species.

A longitudinal study on Raynaud's phenomenon in workers using an impact wrench.

OBJECTIVES: The purpose of this study was to clarify the occurrence of Raynaud's phenomenon among workers using an impact wrench for a long time. METHODS: The subjects were 704 workers regularly using an impact wrench and taking special medical examinations for vibration syndrome from 1981 to 2008. Raynaud's phenomenon was observed in 39 subjects during the observation period. RESULTS: The mean operating years at the occurrence of Raynaud's phenomenon was 25.5 ± 8.3 (standard deviation) yr. The mean total operating time (geometric average) at the occurrence of Raynaud's phenomenon was 11,689 h. By the person-year method, the incidence rate of Raynaud's phenomenon was 6.27 persons per 1,000 person-years. The estimated risk of developing Raynaud's phenomenon did not increase until 12 years after starting to operate an impact wrench but increased exponentially after that. The vibration level of an impact wrench (from 4.9 m/s(2) to 22.6 m/s(2)) exceeded the occupational exposure limit value (4.9 m/s(2)). Various countermeasures, such as introducing automatically apparatus and keeping the working environment warm to protect from cold exposure, were taken at the factory. CONCLUSIONS: These findings showed that the rate of occurrence of Raynaud's phenomenon was not high, although the vibration level of the impact wrench was high. This may result from various countermeasures to prevent the occurrence of Raynaud's phenomenon. A long period of exposure to vibration had the potential to lead to the occurrence of Raynaud's phenomenon even under various countermeasures.

Indium chloride-induced micronuclei in in vivo and in vitro experimental systems.

OBJECTIVES: The aim of this study was to investigate the genotoxic effects of indium trichloride (InCl(3)·4H(2)O; InCl(3)) using the in vivo bone marrow micronucleus test and the in vitro CHL/IU cell micronucleus test. METHOD: BALB/c mice were administered a single intraperitoneal (i.p.) injection of InCl (3) at a dose 0.625, 1.25, 2.5, 5, or 10 mg/kg b.w. The frequency of micronuclei, the ratio of polychromatic erythrocytes to normochromatic erythrocytes (P/N ratio) and body weight gain were determined 24 h after administration of the InCl(3). In the in vitro micronucleus test, CHL/IU cells were treated continuously for 24, 48, or 72 h in the absence of S9mix (the continuous treatment method) and/or for 6 h with or without S9 mix followed by an 18, 42 or 66 h recovery time (the short time treatment method). The frequency of micronuclei was determined at the end of each culture period. RESULTS: The frequency of micronuclei induced by InCl(3) increased in the in vivo erythroblast-erythrocyte micronucleus test using BALB/c mice at doses of 2.5 and 5 mg/kg b.w. The P/N ratio, a marker of bone marrow toxicity, decreased significantly following the injection of InCl(3). Body weight gain was also inhibited by InCl(3). InCl(3) induced micronuclei in the CHL/IU cell micronucleus test in both the continuous treatment method and the short time treatment method, both with and without S9mix. CONCLUSIONS: These results suggest that InCl(3) has a genotoxic effect on mammalian cells both in vivo and in vitro.

The micronucleus test and erythropoiesis: effects of cyclic adenosine monophosphate (cAMP) on micronucleus formation.

The aim of this study was to determine the mechanism of the rodent bone marrow micronucleus test in relation to erythropoiesis. We have previously reported that an acceleration of erythropoiesis increases the frequency of micronucleated polychromatic erythrocytes (MPCE) induced by mutagens. The blood plasma erythropoietin level increased after the injection of N6-2-O-dibutyladenosine-3',5'-cyclic monophosphate into adenosine 3',5'-cyclic monophosphate (cAMP) at a dose of 500 mg/kg. A peak of erythropoietin induction was observed 3 h after the injection of cAMP. cAMP itself did not induce any micronuclei in erythroblasts of BALB/c mice. So, the frequency of MPCE did not increase after injection of cAMP. The highest frequency of MPCE and the dose-response relationship between the cAMP doses and micronucleus frequency were observed 30 h after injection of mitomycin C (MMC) in mice which had been administered cAMP 24 h previously. The highest effect of cAMP on the increase of MPCE was observed when cAMP was given 24 h before MMC injection, thus indicating that accelerating the multiplication of erythroblasts increases the frequency of MPCE induced by mutagens. The induction of MPCE in the bone marrow by three other chemicals (carboquone, 5-fluorouracil, and vincristine) also increased after pretreatment with cAMP. Our results suggest that the increase of MPCE induced by mutagens can be amplified following the acceleration of erythropoiesis by pretreatment with cAMP.

[Occupational poisoning and biological exposure monitoring].

Biological exposure monitoring is available for detecting occupational toxic chemicals. It is possible to evaluate the exposure and adverse effects induced such the occupational toxic chemicals with biological exposure monitoring. It is used in health examination, for the recommendation of occupational exposure limits based on biological exposure monitoring, and for biological exposure indices of the American Conference of Governmental Industrial Hygienists (ACGIH).

Geonotoxicity study of illegal drug MDMA and its nitroso derivative N-MDMA by micronucleus and chromosomal aberration tests using Chinese hamsger lung fibroblast cell line.

OBJECTIVES: An increase in incidence of the illegal use of tablets containing 3,4-methylenedioxymethamphetamine hydrochloride (MDMA) has recently become a widespread social problem. MDMA ingested orally reacts with nitrite in the stomach and is synthesized intoN-nitroso-3,4-methylenedioxymethamphetamine (N-MDMA). The aim of this study is to investigate the genotoxic effects of MDMA and N-MDMA on the basis of the results of an in vitro micronucleus (MN) test and an in vitro chromosomal aberration (CA) test using a Chinese hamster lung fibroblast cell line (CHL/IU). METHODS: Tablets containing MDMA obtained from the Regional Bureau of the Ministry of Health, Labor and Welfare were purified, and N-MDMA was synthesized from MDMA in our laboratory. To evaluate the effects of MDMA and N-MDMA, the MN test established by our laboratory and the CA test in accordance with the guidelines for toxicity studies of drugs recommended by the Ministry of Health, Labor and Welfare were performed. RESULTS: In the MN test, no increased frequency of MNs was not found for MDMA. On the other hand, an apparently increased frequency of MNs was observed for N-MDMA. In the CA test, no CA was found for MDMA, but CA was observed for N-MDMA apparently. CONCLUSION: N-MDMA genotoxicity was observed in the MN and CA tests. However, no MDMA genotoxicity was observed.

Effect of static magnetic field on the induction of micronuclei by some mutagens.

OBJECTIVES: It is important to assess the risk of static magnetic fields (SMFs) on human health, because epidemiological studies have indicated that SMFs play a role in the development of diseases such as leukemia and brain tumor. In our environment, we have numerous chances to be exposed to not only SMFs but also many chemicals containing mutagens. The aim of this study is to investigate the effect of SMFs on the induction of micronuclei induced by some mutagens. METHODS: BALB/c mice were exposed to 4.7 tesla (T) SMF for 24 hr immediately after the injection of carboquone (alkylating agent), colcemid (spindle poison), mitomycin C (cross-linking agent), vincristine (spindle poison), sodium fluoride (a byproduct of aluminum plants under strong SMF) or 1-ethyl-1-nitrosourea (brain tumor-, gliomas- and thymic lymphoma-inducing chemical). RESULTS: The frequency of micronuclei induced by six mutagens increased after co-exposure to SMF. CONCLUSIONS: An additive/synergistic effect of SMF and chemicals was observed from the results of increased frequency of micronuclei induced by mutagens in mouse bone marrow erythrocytes.

Genotoxic effects of N-nitrosoketamine and ketamine as assessed by in vitro micronucleus test in Chinese hamster lung fibroblast cell line.

OBJECTIVES: Ketamine hydrochloride (KT) is a secondary amine that has been safely used as an injectable anesthetic and analgesic to avoid the production of nitroso compounds in the stomach. However, ketamine in the tablet form has recently become an abused, recreational drug. The aim of this study was to investigate the genotoxic effects of N-nitrosoketamine (NKT) and KT on the basis of an in vitro micronucleus (MN) test using a Chinese hamster lung fibroblast cell line (CHL/IU). METHODS: NKT was synthesized from KT in our laboratory. In the MN tests, CHL/IU cells were continuously treated with either NKT or KT for 24, 48, or 72 hours without the S9 mix. The cells were also treated with NKT or KT with or without the S9 mix for 6 hours, followed by a recovery period of 18, 42, or 66 hours (short-term treatment). The results were considered to be statistically significant when the p-values of both Fisher's exact test and the trend test were less than 0.05. RESULTS: After the short-term treatment with either NKT or KT with and without the S9 mix, the frequency of micronuclei significantly increased. However, the frequency of micronuclei did not significantly increase after the continuous treatment with either NKT or KT. Both NKT and KT were determined to be genotoxic in the short-term treatment with or without the S9 mix, but they were determined to be nongenotoxic in continuous treatment. CONCLUSION: Our findings suggest that NKT has a stronger genotoxic effect than KT.

[The state and results of countermeasures for mental health at a certain apparel company].

We speculated that there would be more occupational stress in an apparel company than in other areas of business, because employees work long hours and under poor conditions. We investigated 66 employees of an apparel company who visited an occupational physician to consult about their mental health. There were 561 male and 387 female employees in that company. The employees who had visited an occupational physician had worked long every day under poor conditions, and they had been required to be more artistic than other employees in that company. Female employees visited occupational physicians more than males. Apparel companies, use a system of "specialty store retailer of Private-label Apparel (SPA)", and several sections make special trademark "brands". These sections compete with each other. Employees must plan, design, make patterns, and sew new dresses in a 7-day cycle. They are extremely busy and this therefore creates stress. We came to the conclusion that many apparel companies were stressful workplaces. It is important that a psychiatrist examines employees who occupational physicians have diagnosed as unhealthy. Frequent consultation with occupational physicians is as important as a psychiatrists examination. Managers must manage absence, efficiency, and written correspondence of all employees. These are useful signs of mental disorder. When employees return to work after sick leave, rehabilitation in the workplace after absence is useful. The employee should work for only two hours a day at first. Working hours are then extended gradually. The employee can then return to work easily if this rehabilitation program is followed.

The frequencies of micronuclei induced by cisplatin in newborn rat astrocytes are increased by 50-Hz, 7.5- and 10-mT electromagnetic fields.

OBJECTIVES: Epidemiological studies have suggested that exposure to environmental and occupational electromagnetic fields (EMFs) contribute to the induction of brain tumors, leukemia, and other neoplasms. The aim of this study was to investigate the genotoxic effects of exposure to 50-Hz EMFs. and of co-exposure to cisplatin, a mutagen and carcinogen, and 50-Hz EMFs, using an in vivo newborn rat astrocyte micronucleus assay. METHODS: Three day-old male Sprague-Dawley rats were co-exposed to 50-Hz EMFs and 1.25 or 2.5 mg/kg of cisplatin. Brain cells were dissociated into single cells and cultured for 96 hours, then stained with acridine orange and an antibody against glial fibrillary acidic protein. The frequency of micronucleated astrocytes was counted with a fluorescent microscope. RESULTS: The frequency of micronuclei was not increased in rat astrocytes exposed to EMFs alone. However, the frequencies of micronuclei in co-exposure to 2.5 mg/kg cisplatin and EMFs (7.5- and 10-mT) were significantly increased, compared with those in exposure to 2.5 mg/kg cisplatin alone (sham-exposure, 0-mT EMFs) for 72 hours (p<0.01). CONCLUSION: Exposure to EMFs alone did not have a genotoxic effect but co-exposure to EMFs increased the genotoxic activity induced by cisplatin. Our findings suggest that EMFs enhance the genotoxic effects of cisplatin.

[Investigation of the health condition of the "shukko" person in a certain Japanese company].

The influence of the "shukko" (temporary transfer) work system on health was examined. "Shukko" is a Japanese individual work system. The life-time employment system was general in Japan. "Shukko" work system was devised to reduce the number of personnel in Japan. "Shukko" personnel belong to their present company but they must do the work of another company. Generally, the disadvantages of "shukko". Personnel are greater than in former "shukko" The subjects are 483 office workers in a certain industrial company. 143 workers work in a subsidiary of this company (Age: 42.2 +/- 5.5) (strategic shukko group), 30 workers work in the other company, having resigned their administrative post in the head office (55.6 +/- 2.1) (Demotion by the manager shukko group), and 310 workers work in the head office of this company (41.8 +/- 5.2) (head office working group). The medical examination results (degree of obesity, systolic blood pressure (SBP), GPT, GGTP, total cholesterol, triglyceride (TG), fasting blood sugar (FBS), uric acid (UA), electrocardiography (ECG), and gastrography were compared by mean of multiple regression analysis. In the "Demotion by the manager shukko" group, the average age and SBP were higher than in the other groups. (p < 0.0001). The "strategic shukko" group was compared with the "head office working" group. There is no significant difference in average age. The average SBP (p < 0.001) and FBS (p < 0.0001) of the "head office working" group was significantly higher than those of the "strategic shukko" group. ECG findings were more serious in the "Demotion by the manager shukko" group than in the other groups (p < 0.0001). There is a significant correlation between SBP and "degree of obesity, FBS and UA" (p < 0.0001). There is significant correlation between FBS and "GGTP, SBP, UA, GPT and TG" (p < 0.0001). And there is significant correlation between ECG findings and "working form and SBP" (p < 0.05). The prevention and early diagnosis of geriatric diseases is important for the "Demotion by the manager shukko" group, and their average age is older than that of the other groups. A problem with the head office working group is obesity. In this group it is important to take into consideration life related diseases. The workers complaint a lot in the "strategic shukko" group, but there are no abnormal findings. We think that their complaints are due to their mental stress. In this group measuring mental stress is important.