In order to investigate the effects of toluene exposure on blood and organs of rats with respect to the concentration and the duration, the following experiments were made. Donryu strain male rats were used as the experimental animals. The exposure with low concentrations, i.e. 100 ppm or 200 ppm toluene vapour, was 8 hours a day, 6 days a week, for one year. Examinations were carried out with respect to peripheral blood, liver function, and testes. And the weight of various organs was measured. The exposure with high concentrations was carried out at 2000 ppm toluene vapour for 10, 18 or 43 weeks. And various organs were weighed and examined histopathologically after the exposure. The results of the examination of peripheral blood and liver function are: (1) In 100 ppm and 200 ppm groups appearance ratio of Mommsen's toxic granules tends to increase in linear proportion to the exposed concentration of toluene. (2) In 200 ppm group Leucoindex (N/L <no. of neutrophils against no. of lymphocytes>ratio) tends to decrease. (3) No change in erythrocyte counts and leucocyte counts and (4) No change in serum total protein and choline-esterase activity (Table 2). As to the weight of organs in 2000 ppm group, those of liver and kidneys increased each time after the exposure and those of adrenals increased only at the early stage. The weight of thymus and spleen tended decrease from the beginning and had decreased remarkably at the 43rd week of exposure (Fig.1). In 100 ppm and 200 ppm groups, the weight of testes decreased markedly, while that of liver tended to decrease anyhow, and that of heart increased (Fig.2). As to the histopathological findings, many hyaline droplets were found in the renal tubules in 2000 ppm group. The longer the duration, the more and the larger the hyaline droplets (Photo. 1 and 2). The histopathological findings of the testes in 100 ppm, 200 ppm and the control groups were: degeneration of germinal cells in four animals (33%) of 200 ppm group (Photo. 3, 4, 5 and 6).

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A clinical analysis was made of fourteen cases of methyl bromide poisoning. Thirteen cases occurred in relation to fumigation of foodstuff or wood, the remaining one to preparation of a chemical. Transient hypertension was observed in five cases, contracted visual field in eight, and unilateral nerve signs in three. Five cases resumed normal gait six to eight months after the onset. Eight cases were included in the chronic type, four in the transient type and two in the severe type.

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The effect of inorganic, alkyl, aryl and other mercury compounds on the dorsal root ganglia from chick embryos in culture was studied in order to investigate the relationship between the structure of mercury compounds and the toxicity on the nervous tissue. The results obtained are as follows. 1. When chloride was introduced to the hydrophilic moiety of the mercury compounds instead of iodine, the compounds were found to be more toxic for the outgrowth of Schwann cells and nerve fibers. The binding of a hydrophobic group to the hydrophilic moiety of mercury compounds did not show the decrease in the toxicity. 2. The toxicity of mercury compounds was determined principally by the character of hydrophobic moiety. Phenyl mercury was less toxic than alkyl one. Alkyl mercury compounds having short carbon chains was more toxic than those having longer chains. 3. L-Cysteine hydrochloride, DL-penicillamine (DL-β-mercaptovaline), and BAL (2, 3-dimercaptopropanol) did not inhibit the toxic effect of organic mercury compounds. This results indicate that the mechanism of hydrophilic moiety could not be explained only by the binding of the moiety with SH group of the membranes or proteins. 4. Cholesterol, cholesterol palmitate, cephalin, and lecithin did not inhibit the toxic effect of organic mercury compounds. However, sphingomyelin and phosphatidyl-L-serine tended to improve the outgrowth of Schwann cells and nerve fibers in the presence of organic mercury compounds. These results suggest the specific binding of the hydrophobic moiety with the specific binding sites of the membrane. 5. The degree of the toxicity of the compounds having the multiple sizes of methyl mercury chloride was almost the same as that of methyl mercury chloride itself. This result seems to indicate the presence of the regular distribution of binding sites on the surface of the membrane. 6. It was pointed out that the tissue culture technique of the nervous system was useful to test chemicals from many industries to see whether they have neurotoxicity or not.

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An accurate method for the determination of microamount of chromium in the human urine by atomic absorption spectroscopy is described. And analytical data of 88 human urine samples by this method are shown in this report. About 50ml or 20ml amount of samples is mineralized with nitric acid and sulfuric acid. By reason of taking off the inorganic compound interfering with chromium oxidation, the mineralized residue must be completly decomposed by strong reheating until dense fumes of sulfuric trioxide are carried out. The chromium was oxidized to chromium (VI) with a small amount of 0.01N KMn0₄ solution. Two percent of APDC solution is added to it when the solution pH has been adjusted to 4, and the chromium chelate is extracted into MIBK. The keton extract is aspirated into the acetylene-air flame. Atomic absorption spectroscopy is operated at the highest sensitivity using the 3579Å line of chromium. The limit of detection for chromium was found to be 0.01μg. The recovery of chromium with the entire procedure using the radioactive isotope of chromium was 82.1-94.0 percent. By the aplication of this method, 88 urine samples of 30 persons belonging to three groups (I: chromate producing factory workers, II: the inhabitants in the vicinity of the factory and III: the control) were analyzed. The distribution of frequencies of the analytical date showed positive skewing to cluster near zero, but the distribution of logarithmic values was nearly normal. The representative numerical values of chromium in the urine of these three groups are as follows; 1. Geometric means of the chromium concentration in the urine adjusted for specific gravity of 1.020 were 0.0243 ppm for I group, 0.0030 ppm for II group and 0.0030 ppm for III group. 2. Geometric means of chromium excretion in 8 hours' urine adjusted for creatinine were 19.72μg/g for I group, 2.49μg/g for II group and 2.10μg/g for III group.

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Finger pulse wave was recorded in 144 womens consisting of 100 key-punchers, 24 normal control and 20 patients with scalenus syndrome, by means of a pneumatic strain gauge transducer plethysmograph. The contour of pulse wave was classified in six groups, vis. catacrotic, peak flat, anacrotic, sclerotic rigid, vasospastic and plateau. Geometrical analysis of the pulse wave was carried out, eight indices being adopted. Percentages of the normal pattern of the pulse wave, comprised of catacrotic plus peak flat wave, were ca. 85% in the normal control group, ca. 35% in patients with scalenus syndrome, and ca. 45% in key-punchers. Whereas, those of vasospastic wave plus plateau wave, which is said to represent the spasm of peripheral vessels, were ca. 35% in key-punchers, 6% in the control group and 20% in patients with scalenus syndrome. In the finger pulse wave of key-punchers, a statistically significant decrease of elasticity index, a significant increase of dicrotic index, relatively descending time at the half-way of the peak amplitude, and that of relative amplitude at the half-way of the diastolic phase, and the reduction of peripheral blood flow were observed. The finger pulse wave of key-punchers with complaints represented neurovascular symptoms such as pain, numbness, hyperaesthesia and coldness of the hands, arms and shoulders or the neck, showed only the prolongation of relative ascending time at the halfway of the peak amplitude compared with that of the key-punchers without complaints. Both geometrical analysis and wave form of the finger pulse wave of key-punchers revealed no significant difference in the arms with and without complaints. The finger pulse wave of punchers engazed in key-punching over 10 years indicated a tendency to increase in peripheral vascular resistance, such as the increase in the dicrotic index and the relative descending time at half-way of the peak amplitude, the decrease of the elasticity index and the shorting of the propagation time compared with the group of key-punchers whose length of service are less than 10 years. When the modified Adson's maneuver (elevation of the chin, looking toward right and left side alternatively) was employed in subjects, no significant change was found in geometrical analysis of the finger pulse wave of both the key-punchers and of the control. In the scalenus syndrome group, however, the increase of the relative descending time at half-way of the diastolic phase was observed when the patients rotated his neck to the left side as well as a significant reduction of peripheral blood flow when rotated to the right or the left side. When key-punchers, whose pulse wave classified as vasospastic and plateau type, lay on their back with arms raised so high as 90 degrees in the angle for 30 seconds in the duration, contours of the finger pulse changed from vasospastic or plateau wave to the normal wave (catacrotic or peak flat). Therefore, peripheral hemodynamics of the key-punchers was manifested as vasoconstrictive and its cause would not likely be organic but rather functional. The vasconstriction of the finger, estimated from the finger pulse wave, was more prominent in the group of key-punchers engaged in key-punching more than 10 years and this appeared to be independent of their complaints.

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The effect of steady-state noise (88 dB, exposure for 30 minutes) and the combined effect of it with impulse noise (peak sound pressure 125 dB, time constant 10 ms, i.e. duration of the impulse, frequency every 4 seconds, exposure for 30 minutes) on the temporary threshold shift (TTS) were studied on 5 healthy young men. TTS at both test frequencies of 1kHz and 4kHz was much larger in the latter case. This seems to show that the ability of the steady-state noise to arouse acoustic reflex is just of temporary nature.

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