Minamata Disease from the Viewpoint of Occupational Health: Shigeru NOMURA, et al. Department of Public Health, Kumamoto University School of Medicine-Minamata disease is a neurological disorder caused by methyl mercury poisoning which occurred as the result of ingestion of large quantities of fish and shellfish polluted by industrial waste water in Minamata and Niigata, Japan. More than 40 years have passed since the epidemic was first reported in 1956 in Minamata. Inorganic mercury used as a catalyst in the acetaldehyde process had methylated inside the factory and had then been discharged into Minamata Bay. The waste from the acetaldehyde process continued to pour into the bay until 1968. In the process of researching possible causal elements, the Minamata Disease Study Group of the Kumamoto University School of Medicine found that the clinical and pathological findings in cases of Minamata disease coincided with certain cases of methyl mercury poisoning in England reported in 1940 by D. Hunter and D. S. Russell and which were published in a monograph on occupational toxicology in 1958. The English cases involved the poisoning of workers in a factory producing methyl mercury pesticide. It is clear that occupational poisoning can provide an important guide for the investigation into the cause of an environmental disease such as Minamata disease but there are differences between the two types of poisoning as they occur under different conditions. Occupational poisoning is a direct poisoning of workers which occurs under certain conditions, whereas Minamata disease involves the poisoning of the entire population of a contaminated area, including embryos, the aged and those who are already suffering from other diseases. When these points are considered, it becomes clear that although Minamata disease and occupational poisoning coincide with each other in some respects, they do not in others.

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Assessment of Peripheral. Central and Autonomic Nervous System Functions in Two Lead Smelters with High Blood Lead Concentrations: A Follow-Up Study: Yasushi FUJIMURA, et al. Department of Public Health. School of Medicine. University of Tokyo-To examine the effects of lead on peripheral, central and autonomic nervous system functions, the median and radial motor and sensory nerve conduction velocities (MCV and SCV), distribution of median nerve conduction velocities (DCV), short-latency somatosensory, brainstem auditory and visual evoked potentials (SSEP, BAEP and VEP, respectively), event-related potential (P300), and electrocardiographic R-R interval variability (CVRR) were measured once a month for 12 and 25 months in two male lead smelters with the first blood lead (BPb) concentrations of 105.6 μg/dl (Lead smelter 1) and 76.5 μg/dl (Lead smelter 2), respectively. The measurements were conducted a day before the workers underwent BPb measurement and lead mobilization test with 1-hr calcium disodium ethylenediamine tetraacetate infusion. The following results were obtained: (1) The delayed values for V 20-V90 velocities of the DCV, MCVs in the median and radial nerves, SCV in the median nerve. N13-N 20 interpeak latency of the SSEP, V Iatency of the BAEP, and P300 Iatency in Lead smelter 1 were significantly more frequent than the expected values in control subjects. (2) Also, the delayed values for V 60-V90 velocities of the DCV, MCV and SCV in the median nerve, and N9 Iatency of the SSEP in Lead smelter 2 were significantly more frequent than the expected values in control subjects. (3) The delayed values for MCVs in the median and radial nerves and N13-N20 interpeak (SSEP), V (BAEP) and P300 latencies in Lead smelter 1 were significantly more frequent than those in Lead smelter 2. (4) In the two lead smelters, the delayed values for V80 and V 90 velocities of the DCV were significantly more frequent than those for V10 and V20 velocities. These data suggest that faster nerve fibres of the peripheral nerve are more sensitive to chronic lead exposure than slower nerve fibres are, and peripheral nerve function is more sensitive to chronic lead exposure than central and autonomic nervous system functions.

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Relationship between Body Weight and Somatological Factors by Sex and Age: Yoshiharu FUKUDA, et al. Department of Public Health, Kumamoto University Medical School-To determine the relationship between relative body weight and the somatological factors of blood pressure, serum lipid, liver function and blood sugar by sexage groups, and to evaluate the effectiveness of BMI as a screening index for abnormality in blood tests, we studied cross-sectional health examination data drawn from a population consisting of 6, 989 officials aged 18-65 years in municipalities in Kumamoto prefecture. Japan. Results showed the association between body mass index (BMI) and somatological factors is very strong in young adult males, but weak in middle-aged males. Furthermore, the receiver operating characteristic curve analysis showed that BMI is valid in screening for blood test abnormalities in young adult males. From these results. BMI was found to be a comprehensive parameter of health status and an efficient screening index for blood tests in young adult males. The intervention in obesity appears to be a most advisable goal in primary prevention in young adult males.

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Onset of Peptic Ulcer and its Relation to Work-Related Factors and Life Events : A Prospective Study: Atsuko SUGISAWA. et al. Department of Mental Health Administration Studies. National Institute of Mental Health. National Center of Neurology and Psychiatry-Although peptic ulcer (PU) is counted as one of the various work-related diseases, little is known about the risk factors other than health habits. The authors used data from the Japan Workers Stress and Health Survey-an 18-month follow-up study-to ascertain whether psychosocial factors play any role in the development of PU in the working population. The subjects were 9, 204 men, working at various occupations and firms, aged 30 through 59 years, who had no prior history of PU at baseline. People with extremely severe life event stress had an increased risk of PU compared with those who had no such experience. An increased risk was found when the frequency of late night work was 10-12 times a month compared with none. Five items related to perceived work overload-too much responsibility, poor relations with superior, understaffing, excess of evening/holiday business meetings, and physically too tiring -were each positively associated with PU. Life event stress, frequency of late night work, and perceived work overload were all independently associated with the onset of PU after controlling for age and smoking. These results provide evidence that psychosocial factors play an important role in the development of PU.

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Screening of Helicobacter Pylori Infection in the Health Examination Detected by Urea Breath Test and Barium Meal Study: Fumihiro YAMASAWA, et al. Marubeni Clinic-Background; Helicobacter pylori, H. pylori, is now assumed to be a definite cause of gastric cancer. Health examinations for the early detection of atherosclerotic diseases and malignant diseases have been widely undertaken in Japan, where the incidence of gastric cancer is still one of the highest in the world. To investigate H. pylori infection non-invasively in the regular health examinations, we introduced the urea breath test (UBT) with a barium meal study in the ordinary system. Methods, Sixty male subjects were studied (mean age: 47.8 y/o) in this study. After blood examination for anti H. pylori IgG antibody, the reference expired gas was collected from each subject. Then the subject took 100 mg of ¹³C-urea dissolved in water with tartaric acid and sodium bicarbonate, which was used to distend the stomach, and an ordinary barium meal study was undertaken. Several rotations of the body were added to subjects for fluoroscopy. Thirty minutes after ¹³C-urea intake, the expired gas was collected again as the second gas sample. The ratio of ¹³C to ¹²C jn the reference and second expired gas sample was measured with a mass spectrometer and the changed fraction of the isotope concentration, d, was calculated in each subject. The X-ray films of the barium meal study were read independently by one roentgenologist who was not informed at all about this study. Cases were divided into 2 groups: one group without mucosal inflammatory diseases and another group with mucosal inflammatory diseases. Results; The d value for subjects with positive H. pylori antibody and with mucosal inflammatory diseases, who were strongly suggestive of positive H. pylori infection, had a significantly higher value (d: 2.492±1.372, p<0.001) than that for subjects with negative H. pylori antibody and without mucosal inflammatory diseases, who were thought not to have H. pylori infection (d: 0.141±0.107). Subjects who were strongly suggestive of H. pylori infection showed distinctly higher value. Conclusions; Barium did not interfere with the reaction of H. pylori and ¹³C-urea in the gastric mucosa. UBT can be performed non-invasively together with a barium meal study and it provides useful information on H. pylori infection in the health examination.

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Afternoon Exercise Improves the Quality of Night Sleep: A Case Study Observed by EEG and Self-Rating Scale: SASAZAWA Yosiaki, et al. Department of Public Health. Gunma University School of Medicine-This study was designed to assess the effects of morning (10:00-12:00) and afternoon (15:00-17:00) exercise on the objective and subjective quality of sleep. The subject was a 24-year-old man in the habit of performing soccer exercises. Exercise duration was 2 hr a day with an average exercise load of 70% V0₂max, and the energy expenditure was approximately 1, 300 kcal. The polygraphic parameters of sleep were sleep stages expressed as percentages of total sleep time (%S1, %S2, %S (3+4), %SREM, %MT), time in bed, sleep time, total sleep time, sleep onset latency (SOL), waking from sleep (WAKE), sleep efficiency (SEFl), number of awakenings (NOAW), number of stage shifts, number of spindles and percentages of alpha and delta waves, all of which were assessed by an automatic computer analyzing system. The OSA questionnaire was used to assess the quality of subjective sleep. The five scales of the OSA are sleepiness, sleep maintenance, worry about sleep, integrated sleep feeling and sleep initiation. Comparisons were made between sleep parameters when the subject performed morning exercise and afternoon exercise, and in the non-exercise days by Dunnett's multiple comparison test. Sleep EEGs after afternoon exercise days showed higher %MT (p<0.05), shorter SOL (p<0.05), less WAKE (p<0.05), higher SEFI (p<0.05) and decreased NOAW (p<0.05) than those of non-exercise days. There were no significant differences between any of the sleep EEG parameters on non-exercise and morning exercise days. Only the falling asleep score of the self-rated sleep should be significantly improved by the afternoon exercise. The results suggest that afternoon exercise has a better effect on sleep than morning exercise.

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Dermal and Bronchial Responsiveness of Aluminium Smelter Workers: Evgenije Hošovski, et al. Health Center. Department of Occupational Medicine Uzice-Tests on dermal and bronchial responsiveness were carried out in aluminium smelter workers (exposed group, n=127), and in office workers (control group, n=49). All the participants were male, apparently healthy, and tobacco non-smokers. The studied groups were comparable for all parameters used, but not for occupational environment conditions (i, e. aluminium and other toxic noxae exposure). Patch and prick cutaneous test revealed hypersensitive reaction to pure aluminium, aluminium smelter dust, and histamine in a significant number of exposed workers. Bronchial hyperresponsiveness to acetylcholine (but not to aluminium aerosol) was found in 38.5% of exposed workers, versus 2.0% of the control group. The research showed that mean values for IgA and IgG (but not IgE and IgM), were considerably higher in the serum of exposed workers. In respect to genetic markers, no important difference between the groups studied in alpha- 1 -anti-trypsin values in serum was noted. The changes noted lead to the conclusion that there is an immunological disturbance in workers exposed for a long time to toxic compounds (mainly aluminium) in an aluminum smelter. Present knowledge cannot explain these findings by the adverse effects of aluminium alone.

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The Effects of Allyl Chloride on Ca²⁺, Ca²⁺ Free CaM, CAMP and Ca²⁺/CaM-PK II Activity in Nerve Cells: Keqin X_IE, et al. Institute of Toxicology, Shandong Medical University-Nerve cells in a culture from chicken embryo brain were used to study the allyl chloride-induced effects on the contents of intracellular Ca²⁺, Ca²⁺-free CaM, cAMP and the activity of Ca²⁺/CaM-PK II. The results showed that with the increase in the concentration of allyl chloride there was a significant increase in the content of Ca²⁺and cAMP, and the activity of Ca²⁺/CaM-PK II in the cells (P<0.01), but a marked decrease in Ca²⁺-free CaM (P<0.01). The results suggest that the neurotoxicity of allyl chloride might be related to the increase in intracellular Ca²⁺ and the activation of CaM and Ca²⁺/CaM-PK II, eventually leading to the accumulation of degenerative MT in the nerve axon.

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Gender and Hierarchical Differences in Lead-Contaminated Japanese Bone from the Edo Period: Tamiji NAKASHIMA, et al. Department of Anatomy and Anthropology, University of Occupational and Environmental Health, Japan—Objectives: We analyzed lead concentrations in bones from both genders of the Japanese samurai class and compared findings with those of the farmer and fisherman classes in the Edo period (1603-1867) to clarify gender and hierarchical (or occupational) differences in lead exposure during the Japanese feudal age. Methods: Tests were performed by atomic absorption. Results: Female samurai bones (30.5, μg Pb/g dry bone) showed higher lead concentrations than male samurai bones (15.6μg Pb/g dry bone), but these differences were not significant. This tendency was also seen in the farmer and fisherman classes (male: 1.0μg Pb/g dry bone; female: 1.7μg Pb/g dry bone). Strong hierarchical differences between samurai and farmer/fisherman classes were seen in both genders in this study (p<0.001). One of the female samples from the Samurai class, who was a daughter of the 6th feudal lord in Kokura (Japan), had 945.5 μg Pb/g dry bone. Conclusion: The samurai class were the aristocrats of society. We assume that facial cosmetics (white lead) comprised one of the main routes of lead exposure among the samurai class, because cosmetics were a luxury in that period.

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Formaldehyde Exposure and Low Birth Weight Incidence: Regina GRAZULEVICIENE, et al. Laboratory of Environmental Epidemiology, Institute of Cardiology-A population-based epidemiological study was undertaken to assess the prenatal formaldehyde exposure effect on the incidence of low birth weight newborns in Kaunas area in 1994. All women in childbirth were interviewed in person about their sociodemographic characteristics, habits and reproductive and medical history. We compared 244 cases of low birth weight newborns with 4.089 controls. The comparison involved questionnaire information on 26 potential risk factors in low birth weight. We employed multivariate logistic regression to adjust for potential variable effects of 12 selected low birth weight risk factors. The incidence of low birth weight newborns in Kaunas was 56.2 per 1, 000 live newborns. The crude risk ratio of low birth weight babies among women subjected to formaldehyde exposure was 1.68 (95% CI 1.24-2.27) and to TSP exposure was 1.59 (95% CI 1.13-2.20). The population attributable risk percentages were 14.1% and 4.9%, respectively. Adjustment for age, occupation, education, marital status, hypertonic disease, last pregnancy outcome, parents smoking, hazardous work, formaldehyde, ozone and TSP exposure decreased the formaldehyde effect, OR 1.37 (95% CI 0.90-2.09), and ozone effect, OR 1.44 (95% CI 0.47-4.41), and increased the TSP effect. OR 2.58 (95% CI 1.34-4.99). The study results indicate that among the ambient air pollutants examined TSP exposure had a statistically significant effect on low birth weight risk. Insufficient control of other environmental risk factors could have influenced the observed association

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Biological Monitoring of Inorganic Mercury in Workers in a Fluorescent Lamp Plant. Masako IDEN, et al. Matsushita Electronics Corp., Okayama Factory—The level of mercury in urine is measured as an exposure monitoring of mercury, and the activity of urinary N-acetyl-β-D-glucosaminidase (NAG) is used as an index of adverse effects of mercury on human kidneys. Here we examined the validity of these procedures by comparing the urinary total mercury (U-Hg) level and NAG activity in both 75 male workers exposed to inorganic mercury and age-matched unexposed male workers in a fluorescent lamp plant. To investigate factors affecting the levels of U-Hg, 12 items were selected in relation to oral intake and excretion of mercury: consumption of 1) soft drink, 2) coffee or tea. 3) milk and 4) alcohol; 5) habit of drinking tap water at the work place; frequency of 6) eating fish and 7) alcohol intake; 8) smoking; 9) use of dental amalgam, 10) eating of home grown rice; 11) exercise habit and 12) age. The U-Hg level and NAG activity were adjusted by creatinine levels. Personal exposure levels of inorganic mercury in air (A-Hg) and the U-Hg level correlated well (p<0.001) in the exposed group but neither the exposed nor unexposed group showed a correlation between the U-Hg level and NAG activity. Although the mean level of U-Hg in the exposed group was higher than that in the unexposed (p<0.001), no difference was observed in the mean level of NAG activity. A multiple regression analysis followed by a one-way ANOVA revealed that only the frequency of eating fish per week contributed to increase the level of U-Hg. The results suggest that oral intake of mercury from fish is a possible confounding factor in the exposure monitoring of inorganic mercury in the work place.

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Occupational Exposure to Vibration and Ischemic Heart Disease: Luciana-Daniela TAMAIAN, et al. Pneumoconiosis Lab., Mining Institute, ClujNapoca-150 miners working in an ore mining area were investigated to evaluate the prevalence of ischemic heart disease. They were assigned to three groups: 50 subjects exposed to vibration with signs of Raynaud phenomenon, 50 with similar exposure without Raynaud phenomenon, and the other 50, who were not exposed, representing the control group. The three groups were matched in terms of age, food habits, and hereditary risk factors for ischemic heart disease, smoking habits, Iipemia, and blood cholesterol levels. In the group exposed to vibration, the prevalence of ischemic heart disease was 11% and in controls 6% (P=0.35). The presence or absence of Raynaud phenomenon did not significantly influence the prevalence of ischemic heart disease in the group of subjects exposed to vibration.

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Cholinesterase Status of Some Ethiopian State Farm Workers Exposed to Organophosphate Pesticides : Kibruyisfa LAKEW, et al. Occupational Safety and Health Division. Region 14 Labour and Social Affairs Bureau-The effects of organophosphate (OP) pesticide exposure on cholinesterase (ChE) activities were assessed in relation to occupational factors by studying 430 pest control workers from three state farms and 1 61 comparable controls. Plasma cholinesterase (PChE) and erythrocyte cholinesterase (AChE) activities were determined by an electrometric method. Plasma alkaline phosphatase (AP) and glutamic pyruvic transaminase (GPT) were estimated colorimetrically by using diagnostic kits 6391 and 1442520 respectively. Information on OP poisoning symptoms and related occupational factors were collected based on the WHO recommendations. Pest control workers had significantly lower PChE and AChE activities than the controls (P<0.001). In addition, 58 (13.5%) and 47 (10.9%) of the exposed workers had PChE and AChE activities below the lower limits of the controls respectively. Normal plasma AP and GPT values without significant difference from the controls were noted. Among the exposed population, the “spray men” and those who were exposed for 5 years or less were found to be the most affected groups. Although poisoning symptoms were more frequent in the exposed workers than in the controls, only sweating was found to have an association with a significant reduction in AChE activities (P<0.05). The study revealed that the health risks are more apparent in the exposed workers and are of immediate concern. Pre-placement and periodic medical examination and creation of swareness among the exposed population are recommended to minimize the problem.

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Occupational Medicine in France: A Perspective at the Fiftieth Anniversary of Médecine du Travail:: Bertrand LIBERT, et al. Association Interentreprises de Médecine du Travail de L''ile-de-France-The occupational health system in France was established in 1946, and is quite unique even in comparison with those in the other European countries. The system provides health care service to all the workers in France with the cost paid by employers. The service is provided as medical examinations and work site inspections by certified physicians for occupational medicine; there are 6, 300 certified physicians working in company medical departments or interfirm medical departments which are health care delivery organizations scattered all over the country. The occupational physicians act strictly for prevention, and the health examinations by the occupational physicians are mandatory not only for workers at risk of occupational hazards but for all unspecified workers. This 50-year-old system, however, should be adapted to the changes in the occupational landscape of modern French society, such as downsizing of companies, surging of temporary workers, Iessening the role of manual work and increasing office staff and service employees. Occupational physicians can be and should be involved more in health and safety training for workers, improving work conditions by ergonomic studies, global prevention including cancer and cardiovascular disease, and environment protection. On the other hand, the shortage of 500 occupational physicians today and the decrease in medical graduates who enter the four-year internship for occupational medicine are very touchy problems in the French occupational health system. And harmonization in the occupational health field among participating countries in the European Union may lead, sooner or later, to dramatic changes in the participants and activities of the French system.

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