It has past over 20 years since occupational cerbicobrachial disorders (OCD) among key-punchers and typists became a serious problem in the field of occupational health. Various kinds of improvement of working conditions, such as shortening of operating hours, introduction of new machines with lighter key touches and so on, have reduced the number of operators suffering from the disorder. However, it has not completely solved the problems concerning the disorder. The authors discussed on the relationship between working conditions, including health care services provided, and the results of health examinations among the operators employed in a certain big company. The operators were divided into three groups. The one of them is a group of operators working in the information system room and in the typewriting room. The second is a group of workers operating business machines in various kinds of the office room, some of them being employed as office girls. The third is a group of operators working key punch work in a subcontract company. Results of health examinations of the operators demonstrated that there were more sufferers among the second group than among the other groups. The authors analysed the factors for the outbreak of the disorder by case studies. The authors demonstrated that health care services provided for part-time operators were not enough yet and changes of the key-punch work in its quality had more important impacts to the outbreak of acute symptoms of the disorder rather than the amount of the key-punch work after health care services for the operators had been developed to some degree. New steps are always required to meet the new situation in the field of occupational health.

View full abstract

Among the vibration hazards resulting from the use of vibrating tools, Raynaud's phenomenon, the peripheral nervous disturbances and the bone-joint abnormalities have been well known. Especially, Raynaud's phenomenon, which is explained as a spasm of the peripheral vascular vessels caused by disorders of the peripheral nerves or abnormalities of the arteriolae, represents the peripheral circulatory disturbance. In the worker with such a disorder of the peripheral circulatory function, it is likely that the mechanism of the cold pressor response would have been changed. The authors examined the relationship between the peripheral circulatory function and the cold pressor response in 51 chain saw operators. The following examinations were carried out: skin temperature, nail-press test and cold pressor test by 10-minute-immersion in 10°C water. There was statistically an inverse correlation (γ=-0.316, P1t;0.025) between the increase in systolic blood pressure at the second minute during immersion and the mean skin temperature of the finger-tip during the latter half of 10-minute-immersion. It would be surmised from this result that the worker with lower peripheral circulatory function tends to increase the excitability in the sympathetic nervous system.

View full abstract

In an attempt to develop the technique for long-term inhalation studies, a "multipurpose" inhalation system was deviced. Using this system, an experimental model of the human polluted lung was successfully produced in rats after long lasting inhalation of heavy oil combustion products as a model aerosol. Facilities for concentration regulation of the particulated matter and the actual concentrations obtained throughout this experiment were described in the previous first report. In this second report, newly deviced two types of inhalation chambers are described. One is a typical pyramidal type chamber of about 1m³ with a newly deviced exhaust orifice and another is an economical plane cubic type chamber of about 200l. Their operation characteristics, i.e., distribution of the particulated materials and maintenance of biological environment in the chamber were determined on a series of preliminary experiments under various air exchange rates. From the results routine performance discipline has been established. Data in the biological environment obtained from continuous operations of this inhalation system for over three years are also described. Occurrence of unfavorable respiratory infection was successfully avoided throughout those life long experiments, making the average life span and the main cause of the death of the animals satisfactorily acceptable.

View full abstract

The present survey was carried out on the service of guards in the form of night duty in the shift system in order to elucidate the problems involved. Number of subjects was 148. Out of these, 85 worked under the alternate-day shift system whose average age was 42 years, 47 worked under the permanent night duty system of average age of 50 years, and the remaining 16 were on the normal duty of the average age of 45 years. Under the alternate-day shift system, the portal-to-portal time is 24 hours from 10:00a.m. to the same time of the next day from which about 3.O-3.5 hours are exempted for taking a nap. In the permanent night duty it is from 18:00 or 19:00 to 09:00 or 10:00 of the next day, the portal-to-portal ranging 13-16 hours, usually 15-16 hours. The normal duty covers 8 or 9 hours from 10:00 to 17:00 or 18:00, but with incidental night duty of several hours per month. The problems of the alternate-day shift system and of the permanent night duty system were as follows: (1) Under those two systems, the total monthly portal-to-portal time was 312 hours with additional overtime, the mean becoming 397 hours a month in the alternate-day shift system and 405 hours in the permanent night duty system. These are considerably longer than the working time (249 hours) of the normal duty. (2) As for the frequency of the consecutive night shift, it occurred more than twice at the rate of 23% a month in the alternate-day shift system, and some experienced even 7 consecutive night shifts. Under the permanent night duty system, night duty occupied the greatest part in a month (97%), 3 to 5 consecutive night duties being most usual with an exceptional case of 19 consecutive night duties. (3) Number of night duties per month is 16.1 per month on the average under the alternate-day shift system, while 23.2 under the permanent night duty system. (4) The incidence of the spell of the portal-to-portal exceeding 24 hours was 43% per month under the alternate-day shift system. The longest was 72 hours. Under the permanent night duty system, the incidence of the spell of 19 hours or more was about 15%, and the spell of 24 hours or more occurred at the rate of 9%. (5) From the shift formation point of view, the interval between the preceeding or succeeding spell was sometimes null, but it was usually 8-10 hours. The incidence of the former per month was 4.7 times under the alternate-day shift system and 2.7 times under the permanent night duty system. Incidences of the latter under the two systems were 2.0 and 15.1 times, respectively. (6) Number of holidays per month was 3.0 under the alternate-dayshift system, and, 1.1 under the permanent night duty system. Under the normal duty system, it was 4.6. (7) Number of sick absenteeism with medical certificate was 13 in a year (15.3% of the total employees) under the alternate-day shift system, and 7 (14.9% of the total) under the permanent night duty system. As regards diseases which were the reason of absenteeism, 6 were circulatory, 4 respiratory, 4 digestive, each 1 was musculoskeletal, of connective tissue, hepatic, hemopoietic and mental. Except one patient suffering from a respiratory disease and another suffering from a musculoskeletal disease, all were aged 40 years or over. Under the normal duty system there was no sick absenteeism. (8) Number of workers retired in the past one year was 30 under the alternate-dayshift system, 43 under the permanent night duty system, and 1 under the normal duty system. Ratios of the number of retired workers against those in service were 35, 91 and 6% under the three systems, respectively. In the alternate-day shift and permanent night duty systems, and especially in the latter, the number of retired workers tended to be larger among the middle- and old aged. From these results the following items were considered important: Introduction of such countermeasures as reasonably controlling the total work hours, decrease in the number of days of night duty, reor

View full abstract

Today industrial use of benzidine is restricted in many countries. However, little attention is paid to those substances which may decompose themselves in the body and release benzidine or benzidine-like substances. I investigated the mutagenicity of urinary ingredients of rats to which benzidine and three kinds of azo dyes were separately administered through the alimentary tract. The azo dyes were Direct Black EX (EX), Direct Green BK (BK), and Direct Bordeaux BK (BK), all having 4, 4'-diazobiphenyl group in each structure. The mutagenicity of the urine extract with ether was tested on Salmonella typhimurium TA 98 and TA 100. Urinary metabolites of benzidine showed stronger mutagenicity than benzidine itself on both TA 98 and TA 100 in the presence of S9 mix. EX itself showed mutagenicity only on TA 98, whereas B and BK were nonmutagens. Nevertheless, the urine extract of each azo dye showed strong mutagenicity of the same pattern as benzidine. As a result it is suggested that benzidine might be released in the intestine of experimental animals after the administration of each azo dye. Mutagenic activity of urine sample is important and full of suggestions from the viewpoint of carcinogenicity of aromatic amines.

View full abstract