Hideyoshi Suzuki

Absence of blue-yellow color vision loss among workers exposed to toluene or tetrachloroethylene, mostly at levels below occupational exposure limits

SummaryPossible color vision loss was examined with Lanthonys new color test and Ishiharas color vision test in 261 solvent workers and 120 controls (48 men and 72 women). The solvent workers were exposed to either predominantly toluene [46 ppm as geometric mean (GM); 63 men and 111 women], tetrachloroethylene alone (13 ppm; 30 men and 34 women), or a mixture (14 men and 9 women) of tetrachloroethylene (12 ppm) and trichloroethylene (7 ppm). The only instances of color vision loss that were detected in either the exposed workers or the controls were six cases of red-green loss (all in men). These six cases of red-green loss showed an unbiased distribution between the exposed workers and the nonexposed controls.

VIBRATION SYNDROME AMONG FORESTRY WORKERS IN PRIVATE ENTERPRISES IN FUKUSHIMA PREFECTURE

A field study of vibration syndrome has been made on 404 forestry workers (among whom 2 women were included) employed in 95 private enterprises in Fukushima Prefecture. The investigation was carried out from January to March of 1976 and from December of 1976 to February of 1977. Questionnaires and interviews concerning the history of vibration exposure and the occurrence of vibration syndrome were used, and standard medical examinations for the vibration syndrome, i.e. examinations of cutaneous senses and peripheral vascular functions of the hands, were carried out in every subject. Data of work conditions, subjective symptoms, sensory thresholds and peripheral vascular functions among workers were analysed and summarized as follows: 1. Ninety-seven percent of the subjects had been engaged exclusively or mainly in the chain saw work, while 3% of them exclusively or mainly in bush cleaner work. 2. Prevalence of Raynauds phenomenon was found in 30.9% of all the subjects, and attack rate of the phenomenon exceeded 50% of the workers after 11 years of work with vibrating tools. Of all 404 workers 5.7% had suffered from the phenomenon only a year or more before the time of the investigation. 3. Average working hours per day with vibrating tools of the sufferers from the phenomenon was longer than those of non-sufferers. 4. Seventy percent of them were pieceworkers. It was supposed that they could not shorten the time of work with vibrating tools under the system of piecework payment. 5. Symptoms of which twenty-five percent or over of all the workers complained were numbness or paresthesia, chilling, shoulder stiffness, transient lumbago, increasing fatigability, heavy feeling in the arms, high sensitiveness to cold, inclination to wear heavy clothes and pains in the hands or the arms. 6. Cardinal symptoms of which sufferers from the phenomenon complained more than non-sufferers were chilling, numbness or paresthesia, high sensitiveness to cold, heavy feeling in the arms and pains in the hands or the arms. 7. Sufferers from the phenomenon had higher prevalence of disturbances than non-sufferers in the pain sense and the vibratory sense of the hands, and they also showed slightly higher prevalence of low skin temperature and of prolonged recovery time of the blood flow in the hail-bed. 8. It was considered that the higher prevalence of sensory disturbances and peripheral vascular dysfunctions among the sufferers might be attributed to their longer working hours in a day with vibrating tools. 9. It was noteworthy that there were not a few workers among the non-sufferers who showed a high degree of sensory disturbances. 10. There was a correlation of thresholds between pain sense and vivratory sense among the non-sufferers but not among the sufferers. 11. Correlations between skin temperature and recovery time of the blood flow in the nail-bed were observed both among the sufferers and among the non-sufferers.

VIBRATION SYNDROME OF VIBRATING TOOL USERS IN A FACTORY OF STEEL FOUNDRY

A study has been conducted on 71 men using vibratory tools in a factory of steel foundry situated in Fukushima Prefecture in Japan. They have been engaged in the work with pneumatic instruments : 21 men, chipping hammer (CH) work ; 29 men, air grinder (AG) work ; 4 men, sand rammer (SR) work ; 16 men, work with mixed tools mentioned above (MT). The users were interviewed principally on the basis of the standard form of the questionnaire which had been designed by Labor Ministry as the guide for the survey of vibration syndrome in forest workers. The operating hours with CH, AG and SR were about 2, from 5 to 6 and from 1 to 2 hours per day, respectively. Seventeen out of 71 men had worked for less than 1/2 year.The data obtained were analysed and summarized as follows : 1. The group of CH users who worked for 1/2 year or more showed higher prevalence of Raynauds phenomenon and hypoesthesia or paresthesia than the group of 17 users who worked for less than 1/2 year.2. The group of AG users who worked for 1/2 year or more indicated higher prevalence of Raynauds phenomenon and fatigue than the group of users who worked for less than 1/2 year.3. The attacks of Raynauds phenomenon in the CH users were restricted to the left hand which held a chisel.4. The prevalence rates of Raynauds phenomenon in the groups of CH, AG and MT users were 23%, 23% and 25%, respectively, and when taken account of the occurence rate in each period of the experience of the work, the cummulative values reached to 31%, 69% and 23% in the groups of CH, AG and MT users, respectively.5. No Raynauds phenomenon was observed among SR users.6. The attack of Raynauds phenomenon was observed exclusively in cold season and occurred almost on the way to work shop or before leaving home in the early morning and rarely in the working premises.7. The workers who suffered from Raynauds phenomenon had more complaints of hypoesthesia or paresthesia, heavy feeling in arms and difficulty in writing clearly than those who did not have the phenomenon.

AN EXPERIMENTAL STUDY ON PHYSIOLOGICAL FUNCTIONS OF THE AUTONOMIC NERVOUS SYSTEM OF MAN EXPOSED TO ACETON GAS

An experimental study was carried out to obtain physiological data substantiating the maximum allowable concentration of aceton gas in industrial hygiene. For this purpose it was intented to detect polygraphically the variations of physiological functions of the autonomic nervous system of man evoked by exposure to 250-270 ppm or 500-750 ppm concentration of aceton gas for 6 hours, with 1 hour free from aceton gas exposure in the middle, that is, from 9 : 00 to 12 : 00 a.m. and from 1 : 00 to 4 : 00 p.m. Subjects consisted of volunteers of 24 healthy male students (age; 18-28), which were devided into 3 groups (group of control of 8 students, group of low concentrations of 9 students, and group of high concentrations of 9 students, 2 of them being duplicated). They were individually examined while resting in bed for 6 hours (Tests for about 1 hour were repeated 6 times with pauses in between) a day for consecutive two days, and exposed to the aceton gas on the 2nd day except the control. Spontaneous variations and evoked variations in response to 1 second or 30 second auditory and visual incitements by “The Sound and Photo Stimulator for EEG” were observed throughout the experiment, but only the variations during the last 1 hour of both days were compared individually. On the other hand, the tendency of the variations and of the correlations between the phenomena in each group were compared between the 3 groups. The results thus obtained are as follows : 1) Galvanic skin reflexSpontaneous GSR after repeated stimuli decreased in the gas groups, while evoked GSR with repeated 30 sec. stimuli increased in the 250-270 ppm group. The latter phenomenon would probably be derived from both effects of the aceton gas and the high air temperature of the examination room. The evoked GSR with repeated 1 sec. stimuli and latent time of the reaction to 1 sec. stimuli showed no difference between three groups. Tendency of correlation between GSR and air temperature in the gas groups differed from that in the control group.2) Reflection photoelectric finger plethysmogramVasoconstrictive reaction and latent time of the reaction to stimuli and patterns of plethysmogram showed no difference between three groups. But, tendency of correlation between vasoconstrictive reaction to 30 sec. stimuli and air temperature in the gas groups differed from that in the control group.3) Period of heart beatPeriod of heart beat in the 500 ppm group shortened, while that in the control group lengthened. Tendency of correlation between the period and air temperature in the gas groups differed from that in the control group.4) Period of respirationPeriod of respiration showed no difference between the three groups. But, tendency of correlation between the period and air temperature in the gas groups differed from that in the control group.5) Cerebral activity from occipital electroencephalographCerebral activities in the gas groups rised in comparison with the control group. Tendency of correlation between the cerebral activity and air temperature in the gas groups differed from that in the control group.6) It was concluded that the aceton gas influenced not only the spontaneous GSR, the period of heart beat and the cerebral activity, but also the correlations between the physiological functions of the autonomic nervous system, air temperature and the cerebral activity.7) From these facts it is a matter of course that the MAC of aceton gas must be lowered to the level below 250 ppm.

RECENT CONDITIONS OF DERMATOSES CAUSED BY MISCELLANEOUS CHEMICALS IN AN HEAVY ELECTRIC INDUSTRY

An investigation of the skin hazards due to chemicals in one, which employs approximately 5, 000 workers, of the biggest factories of dynamos and transformers in Japan was undertaken for studying the recent problems involved in heavy electric industries and for making recomendations looking for the elimination of hazards. Facts revealed from the inspection of the workers were as follows : 1) There were many cases of dermatoses caused by miscellaneous chemicals among those who had been in contact with it.2) The cutting oil was the most causative material in all chemicals. Next to it was the insulating oil.3) Oil acne among those in contact with the cutting oil or the insulating oil did not disappear throughout the year as long as they remined in contact with it.4) Those workers who had been in contact with phenol-formaldehyde resin in shell-molding process had higher ratios of dermatitis.5) The dermatitis in shell-molding process went worse during several months of hot weather, especially in summer, and almost disappeared in winter.6) In sporadic dermatitis reported to the medical center in the factory the most causative agent was epoxy resin and the next were organic solvents. The others were miscellaneous mineral oil, glass fiber, rust inhibitor, styrol or other resins, coat stripping agents, acid cleaning agents, sulphuric acid, welding agents, binding agents for rubber, and ammonia.7) In the electroplating process there were a few cases of dermatoses due to the chemicals because of improvement of the working environment and the method in the processing.