Katsunori Homma

Changes of the activities of superoxide dismutase after exposure to the fume of heavy metals and the significance of zinc in the tissue.

Pathological changes induced by cadmium aerosol had features common to the changes evoked by oxidants. Female rats were exposed to fumes of lead, antimony, zinc and cadmium (15–100 nmoles/m3). One hour after termination of exposure, superoxide dismutase (SOD) activity in erythrocytes of the exposed rats lowered by 15–40%. SOD activity of lung lavage fluid also lowered by 20–35% at the 2nd day after the exposure. The inverse value of SOD activity (l/SOD) in erythrocytes and of lung lavage fluid were proportional to the molar exposure level adjusted by the particle size (Dixon plot), irrespective of the difference of the exposed substance. The ratio of dry weight to wet weight of the lung was 4.3–26% lower than the control value on the later period after the exposure. With the heavy metal exposure, the uptake of the exposed metal was found to be proportional to the endogenous zinc concentration, which was correlated well with the change of SOD in the lung and in erythrocytes. Cadmium decreased the zinc concentration after the exposure.

RESPONSES OF ALVEOLAR MACROPHAGE TO METALLIC FUME

Alveolar macrophage was lavaged from lungs of rats exposed to inhalation of the particles of Sb, Pb, Cd, CaCO3 or poly vinyl chloride (PVC) and its number and 14C-leucine incorporating activity were studied. The number of free cell lavaged from the lung decreased remarkably by the exposure to Sb or Cd fume, while by the exposure to Pb fume, CaCO3 or PVC particles the number of lavaged cells did not change from that of control group breathing air in the exposure chamber. There was found a linear correlation 1 hr after inhalation between 14C-leucine in-corporation value for total cell and the number of lavaged cell in all the experi-mental groups except unrestrained (bred freely under normal condition) group and Sb group. That is, the incorporation value per cell in all the experimental groups except Sb group and unrestrained group was almost equal. In the case of Sb group and unrestained group the incorporation value per cell was lower than those of the other groups. Although the incorporation of 14C-leucine into cell in control group decreased by level of unrestrained group 21 hr after inhalation, in the Pb, CaCO3 or PVC group 14C-leucine incorporation into cell 21th hour did not change from that 1 hr after inhalation. 14C-leucine incorporation per cell in Sb group 21 hr after inhalation remarkably increased. This tendency was also seen in Cd group.The effects of the particles used in the inhalation experiment on the macrophage in vitro were also studied. The Sb fume was the most effective of all the samples and followed by Cd fume and then by Pb fume. The particles of CaCO3 or PVC were practically inert to the macrophage.

A STUDY OF GENERATING CONDITIONS AND THE SAMPLING METHOD OF CYANIDES IN THE ATMOSPHERIC AIR

Atmospheric concentrations of cyanides in various kinds of plating workshops were determined, and it was cleared that there was an intimate relation between the atmospheric concentration of cyanides and pH of the plating solutions. The more alkaline the solution, the less became the concentration of cyanides. Cyanides contained in the overflowed solution from the plating bath changed to hydrogen cyanide gas while the solution dried up spontaneously, and this gas diffused into the workshop.For sampling cyanides in the air, impinger should be used. The sampling ability of the sampling solution was closely related with its alkalinity. If the aqueous solution of sodium hydroxide is used as the sampling solution, the alkalinity of the solution should be more than 0.2 normal for long time bubbling and more than 0.02 normal for short time bubbling. During the bubbling procedure, the alkalinity of the sampling solution decreased gradually. And the solution should not be used for sampling cyanides if its alkalinity is less than 0.001 normal. If the alkalinity of the sampling solution is exhausted, this solution can not preserve the captured cyanides any more.

EFFECTS OF OXIDES OF SULPHUR ON THIN METAL FILMS

Effects of sulphur dioxide gas, mists of aqueous sulphur dioxide and of sulphuricacid solution and silica gel particles exposed to sulphur dioxide and to sulphuric acid solution on the metal film were studied electronmicroscopically. Mists of aqueous solution of sulphur dioxide and sulphuric acid showed very similar but a little different figures. Sulphur dioxide and particles, absorbing sulphur dioxide or sulphuric acid, showed a corrosive effect on the metals with or after the exposure to high humidity.It was emphasized that the biological effects of these pollutants should be consideredtogether with air humidity.