The present paper is to give a review of the recent studies of organic solvents : the studies of the post-war tendency of the researches of organic solvents in Japan have been checked up, the studies of the organic solvents for the last 6 years were carefully analysed with the helpful material from the reports made at the annual meetings of the Japan Association of Industrial Health, in the comparison with the overseas studies published in the Abstracts of Hygiene for these 5 years, and then the studies of organic solvents in the present Japan are discussed.
The variety of organic solvents reported for these 6 years in Japan is about 30 kinds and about 40 kinds in the other countries. The number, however, comes only to a small percentage of the total kinds which will possibly amount up to 450 at the least. It is urgently required for us to know the actual conditions about the amounts of consumption of the other solvents and the administrative control and security in use of them.
At present, in Japan we have the most numerous reports of toluene, those of trichloroethylene following, while in the other countries, the studies of carbon disulfide are the most, those of trichloroethylene following, and worthy of note are that there are considerable number of the studies of halogenated hydrocarbons.
In Japan, we have comparatively many studies of animal experiments, and accordingly are numerous the reports on the experimental researches made through biochemical method, of the methabolism of organic solvents and of the urinary metabolites, while in the other countries 85% of the reports for the last 5 years are those of the cases of poisoning and of the researches of the biological response through clinical method in the cases of working men.
The recent tendency shows that, in Japan, peripheral nervous system and central nervous system are considerably concerned as the possible indices of the biological response, and that in the other countries they are turning their increasing attentions to interbrain, autonomic nervous system and hormonal system as the indices.

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Six workers who had used chain-saws for about 5 to 6 years and suffered from repeated attacks of Raynaud's phenomenon were chosen and the changes of their peripheral circulatory functions, peripheral nerve functions and subjective symptoms were investigated before and after the introduction of bus survice for their daily transport.
The results revealed that, though the Raynaud's phenomenon per se subsided remarkably after stopping riding bicycles to the working spot, possibly by reducing the chance of inducing the phenomenon, the peripheral circulatory and nerve functions as well as other local and general symptoms still showed a tendency to get worse.
From the data, it is suggested that the occurrence of Raynaud's phenomenon may be attributed not only to the quantity but also to the quality of the induction risk. So we should pay attention to the persistent peripheral circulatory functions, considering it as one of the important diagnostic criteria for the diagnosis of vibration hazards irrespective of the existence or absence of the Raynoud's phenomenon.

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The physiological functions of man exposed for 6 hours (9.00-12.00 and 13.00-16.00) to 200 ppm concentration of toluene gas were polygraphically investigated to obtain the data substantiating the maximum allowable concentration in industrial hygiene.
Subjects consisted of volunteers of healthy 10 male students (age : 18-22). They were divided into 2 groups (controls : 5 and those exposed to the gas : 5), they laid on the bet 6 hours a day, for consecutive two days and only on the 2nd day the exposure group was exposed to 200 ppm concentration of toluene gas. The functions in each subject during the last 1 hour on both days were compared, and the tendency of the phenomena for 2nd days was compared between 2 groups.
Results thus obtained were as follows :
1) Evoked and spontaneous galvanic skin reflex : Any change was not observed.
2) Evoked vasoconstriction by finger-plethysmography : Any change was not observed.
3) Heart rate : The toluene-gas group had a tendency of statistically significant rise.
4) Respiration rate : The toluene-gas group had a tendency of rise, but it was not significant statistically.
5) Cerebral activity from EEG : The toluene-gas group had a tendency of rise in cerebral activity, but this was not significant statistically.

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1. Japan is producing a large amount of vinyl chloride and is now second to the United States of America in its production. In 1954 Kubota reported that cases of Raynaud's phenomena had been found among a dozen or so workers engaged in the manufacture of vinyl chloride at a factory in the northeastern district of Japan. Later, during the years from 1964 to 1967, it was reported in foreign countries that hepatomegaly, Raynaud's phenomena, scleroderma, characteristic acroosteolysis, etc. were detected among workers engaged in the manufacture of vinyl chloride. But these reports did not atract particular attentions of Japanese physicians.
In 1969 Magnuson et al. reported at the XVI International Congress on Occupational Health held in Tokyo that acroosteolysis had been found among workers engaged in the production of vinyl chloride. This presentation aroused our suspicion that similar diseases might exist among vinyl chloride workers in Japan.
In 1970 Masuda re-examined the three workers, who, according to Kubota, had been suffering from Raynaud's phenomena 17 to 18 years before and reported that Raynaud's phenomena and acroosteolysis were not found. These are the only suspected cases of vinyl chloride toxicosis documented in Japanese medical literature.
2. We happened to come across a 36-years-old male patient who had been working in the production of vinyl chloride. He was operated on to remove the right thoratic sympathetic nerve ganglia (II, III) at Nagoya University Hospital for the relief of Raynaud's phenomena, spontaneous pain in the right hand fingers, etc. We studied the patient's record, the physicians' findings and the job the patient had and tried to find any relation between them.
3. Since he was 23 years old he has been working as a cleaner of the polymerizing reactor for four years and a half. It used to take him from 30 to 45 minutes to clean one reactor and he cleaned three to four reactors in one day.
4. After he had been engaged in reactor cleaning he began to suffer from diarrhoea, Raynaud's phenomena, scleroderma, indurations of both hands and spontaneous pain in the right hand fingers (II, III). An X-Ray examination revealed acroosteolysis of the right hand fingers (II, III, IV). Pathohistological findings of the skin of the left hand were as follows : epidermis was normal, collagen fibres were edematous, and thickened wall and infarction of vessels were present in the corium.
5. The nature of his job and his physical disorders well coincided with those of the patients engaged in the production of vinyl chloride and with the results of the animal experiments reported by foreign authors. Thus it was thought logical to presume that his physical disorders were caused by handling vinyl chloride.
6. At present, nine years since he gave up his cleaning job, shortening of his right hand fingers (II, III, IV), paresthesis of the right half of his body, abnormal EEG, hypertention, hyperbilirubinemia and slight angiosclerotic changes in the optic fundi still exists. Literature seems to point out that these disorders are some of the segualae of the vinyl chloride poisoning.
7. As there have been a large number of the manufacturers of vinyl chloride in Japan, there may exist many workers who are already poisoned by vinyl chloride.
8. Among biological effects of vinyl chloride are Raynaud's phenomena, acroosteolysis, scleroderma, increase of blood pressure, etc. And we think it may be very useful to make its toxicity clear in order to help reestimate the toxicity of all the doubtful substances.
9. MAC of vinyl chloride in Japan is 500 ppm at present, but we think that it is too high and should be revised.

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