Transference and transformation of chromium compounds, known as occupational carcinogens, in the lung of rats were studied by determining blood chromium levels after a single mist inhalation or an intravenous injection of water-soluble chromic acid (hexavalent) and chromium chloride (trivalent). Conclusion drawn from this study are as follows; 1. Transference of chromium from the lung to the blood stream is ended quickly after the inhalation of chromic acid mist. 2. Alveolar permeability of hexavalent chromic acid is much higher than that of trivalent chromium chloride. 3. The greater part of the transferred chromium in the blood after the inhalation of chromic acid mist is not transformed to any other form; therefore, it seems to be present as the hexavalent form. 4. The hexavalent chromic acid in the blood diffused to the liver, kidneys and the spleen, but the trivalent chromium chloride distributed only in the blood. 5. The hexavalent chromic acid in the blood decreased more slowly than the trivalent chromium chloride. The biological half-time of the chromic acid in the blood was about 60 hours, whereas that of the chromium chloride was only about 2 hours. These results suggest that the water-soluble hexavalent chromium compounds may be apparently different from the trivalent chromium compounds in the transference from the lung and following distribution in the body. These differences might be caused by the high permeability through the cell membrane in hexavalent chromium compounds and the high possibility of binding with proteins in trivalent chromium compounds.

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In order to clarify the relationship between exposure to hard metal dust containing cobalt and bronchopulmonary diseases, cross-sectional medical and occupational hygienic investigations were conducted in a hard metal tool manufacturing factory. As a part of the environmental investigation, general air concentrations and personal exposure to both total dust and cobalt dust were measured. The highest total dust and cobalt concentrations in general atmosphere and personal samples were found in a powder handling room among all departments. The highest personal exposure concentration of cobalt was 1.29 mg/m³ (arithmetic mean value) in the dry grinder using diamond wheels. Powder handlers were exposed to cobalt 0.56 mg/m³, press operators to 0.66 mg/m³, shapers to 0.19 mg/m³, wet grinders to 0.07 mg/m³, and sintering workers to 0.03 mg/m³. In Japan TLV for cobalt has not yet been established. Dust exposure measurement should be carried out in all hard metal industries. TLV for cobalt is discussed by means of literature.

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The nature of anemia formation in lead poisoning is still unknown, especially of its mechanism. Rimington proposed a hypothesis that lead interferes with a specific enzyme (ferrochelatase) system, which is responsible for incorporating iron into the protoporphyrin IX molecules to form heme. In the present study, heme synthesis in mitochondria (Mt) of liver and bone marrow, and ⁵⁹ Fe behavior in vivo were investigated in rabbits to verify his hypothesis. The experimental five groups were as follows: 1) lead (Pb) poisoning by administration of 10-20 mg Pb/kg at a time, subcutaneously injected 10 times in all during 30 days, 2) phenylhydrazine (PH) poisoning, 10 mg PH/kg, 3 times subcutaneously during 3 days, 3) bleeding of about 105 ml of blood in total by venesection through 7 times treatments, 4) low feeding, synthetic feeding pellets of 30 g/d/cap. or 70 g/d/cap. 5) control, by administration of 5% glucose instead of lead injection with 120 g/d/cap. of the feeding pellets, with drinking water 300 ml/d/cap. for 30 days. ⁵⁹ Fe-plasma was prepared by the following procedure: 5 ml of plasma from each rabbit having been incubated with 5 μCi of ⁵⁹ Fe citrate at 37°C for 30 minutes, ⁵⁹ Fe-plasma was purified partially by Borova's method. The prepared ⁵⁹ Fe-plasma was injected intravenously into the rabbits in each group. Urinary coproporphrin (CP-U), eythrocyte protoporphyrin (FFP), Hb, Ht, MCHC, reticulocyte (Rt), and protoheme formed by Mt, were determined to examine the relationship between lead and porphyrinheme metabolism. ⁵⁹ Fe behavior was estimated by detecting the plasma iron disappearence rate (half life time of ⁵⁹ Fe in plasma), ⁵⁹ Fe intake into erythrocytes, and the retention of ⁵⁹ Fe in tissues. Increase of FEP in lead poisoning was not caused by hemolysis, because FEP did not increase in PH group (Table 1). CP-U slightly increased in PH group, but not in the bleeding group (Table 2). This increase of CP-U must be due to acceleration of hematopoiesis in PH poisoning, because PH and bleeding groups showed an increase of Rt, counting 222.2 and 85.3‰, respectively, at the termination of the treatment, while the Pb group did not show any obvious reticulocytosis (Table 3). PH, bleeding, and Pb (10 mg/kg) groups showed shorter half life time of ⁵⁹ Fe in plasma, while the 30 g/d-feeding group showed longer time (Table 8). During 100 minutes after ⁵⁹ Fe injection, incorporation of ⁵⁹ Fe into erythrocytes was higher in PH and bleeding groups than those in othr treatment groups and the control (Table 9). During 5 days after ⁵⁹ Fe administration, ⁵⁹ Fe incorporation was lower in Pb group, but higher in PH and bleeding groups (Figs. 2 and 3). Pb group and the control group showed almost simillar ⁵⁹ Fe activities in the liver (Table 10). Much incorporation of ⁵⁹ Fe into spleen was observed in PH group (Table 11). On the other hand, much retention of ⁵⁹ Fe was detected in the bone marrow and its Mt of the animals of Pb group, but not in the groups of bleeding and PH (Tables 11 and 13). These results indicate that the heme synthetase (ferrochelatase) is inhibited by lead, inspite of much accumulation of ⁵⁹ Fe in bone marrow and in its Mt. This suggests that Fe in Mt is not effectively utilized for heme formation in lead poisoning.

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In order to investigate into whether the large amount of inorganic lead excreted into the feces following intravenous injection of tetraethyl lead to rabbits is derived from the diethyl lead excreted into the bile, we administered 12 mg/kg of tetraethyl lead to rabbits which had been fistulated into the bile duct for taking the bile out of the body. The total lead excreted into the bile during the first 24 hours after the injection of tetraethyl lead amounted to about 8% of the injected amount of lead (with 97% of the excreted lead made up of diethyl lead). The amount of total lead contained in the cecal contents of unfistulated rabbits 24 hours after the injection of tetraethyl lead was equivalent to about 12% of the injected amount of lead (with inorganic lead accounting for about 90% of the excreted lead), but the counterpart of the fistulated rabbits was equivalent only to about 0.6%. The amount of lead excreted into the bile, when measured in terms of the total lead content of the liver, was slightly less in the fistulated rabbits than in the unfistulated ones. These findings indicated that the amount of total lead excreted into the bile of the fistulated rabbits was almost the same as that contained in the cecal contents of unfistulated rabbits, and that the major portion of the lead contained in the cecal contents or feces was composed of inorganic lead. From these results, we came to the conclusion that the large amount of inorganic lead detected in the feces after the injection oftetraethyl lead is derived from the diethyl lead excreted into the bile.

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New passive personal monitors for organic vapors in work places: the New Du Pont PRO-TEK^TM G-AA Organic Vapor Air Monitoring Badge (A) and the 3M Brand Organic vapor Monitor (B), were tested under certain experimental conditions. Organic solvents adsorbed on activated carbon strip through the diffusion paths of badges were determined by means of gas chromatography and the results were compared with theoretical values. The experimental results well agreed with the theoretical values and the diffusion of organic vapors through the diffusion paths of these passive personal monitors could be estimated theoretically by the Fick's second law of diffusion. If the "relative response time" is defined as the value of Dt/L² at C/C₀= 0.632, the relative response time of these samplers is 1.3. The response time of the two badges for organic vapors for toluene, ethylbenzene and ethyl acetate were caluculated from the above mentioned Dt/L²= 1.3, that is, 2.1, 2.2 and 1.9 seconds for A badge and 13.4, 14.0 and 12.3 seconds for B badge to each solvent respectively. From the results of this experiment, it was found that the responce time of A badge was remarkably faster than that of B badge, and even A badge needed 7-10 seconds exposure to reflect the environmental concentration.

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