A field survey was carried out for the purpose of the establishment of measuring method of vibration caused by portable vibrating tools and clsssification of tools with regard to grades of their vibration magnitude. More than one hundred tools includ-ing electric, gasoline engine and pneumatic tools were investigated. Vibration ac-celeration levels (dBAL) and vibration levels (dBVL) which were values weighted with an electric circuit corresponding to human hand vibration sensation, and fre-quency spectra were determined on these tools. A reasonable measuring method of vibration could be proposed through the experiences and practical situation of the tools could be grasped.
Action of benzene on human leucocytes and on HeLa cells were examined from cytokinetic and cytogenetic points of view. Dose-response type analysis revealed that decreased DNA synthesis of cultured human leucocytes and of HeLa cells were re-markable in dose level of 2.2×10-3 M of benzene. As far as chromosome aberrations of cultured human leucocytes were concerned, gaps and breaks were observed in dose levels of both 2.2×10-3 M and 1.1×10-3 M of benzene.
A clear dose-response relationship was observed between given doses of cadmium (Cd) and levels of sulfhydryl (SH) groups in the special protein fractions extracted from livers and kidneys of the exposed mice. Correlation efficients were 0.906 and 0.892 between doses and SH levels in livers and kidneys respectively. Several heavy metals other than Cd were examined in regard to dose-response relationship in the same manner as Cd. Administration of Fe, Zn and Cr, even though in high doses, did not clearly increase the SH contents both in livers and kidneys. On the other hand, an obvious increase of SH levels was observed in the proteins from livers obtained from Cu-exposed mice. These data indicate that the SH contents in the tissue give the most valid in-formation as to the evaluation of the degree of Cd-exposure. In these connections, differnt responses of the living systems to various heavy metals and a possible roll of the SH-rich proteins which increase in the tissues exposed to heavy metals were discussed.
Some biological indicators of lead absorption from 23 lead smelters were examined three times. By an accidental a month's discontinuation of exposure, mean concentra-tions of coproporpyrin and delta-aminolevulinic acid in urine decreased to one third, and also positive rates of subjective complaints to one half, but hemoglobin content, stippled cells, polychromatic cells, reticulocytes and lead concentration showed much less improvement. Factor analysis of the indicators revealed the concentration of coproporphyrin in urine had a very different character among them. Ninety three percent of the data matrix of them were explained by the four factors. Mean con-centration of delta-aminolevulinic acid in serum was 35.5±11.4μg/d1 and renal clear-ance and renal reabsorption rate of the substance was 11.2 to 16.9 ml/min and 92.5 to 97.5%, respectively, concerning the six admitted smelters except one case. Concentra-tion of delta-aminolevulinic acid in serum will never be so an excellent indicators, but may be a key substance of delta-aminolevulinic acid and coproporphyrin excretion to urine.
Ultrastructural localization of inhaled submicron lead fume was studied on the lungs of rats. The specimens were obtained from two series of experimental exposure to metallic lead fume of 0.3μ in projected diameter (σg 1.31, AMD= 1.1μ) in concentra-tion of 120mg/m3 in the first experiment and 0.04 μ in projected diameter (σg 1.40, AMD= 0.19μ) in concentration of 10mg/m3 in the second experiment respectively. Qualitative identification of lead nature of the fine particles deposited in the tissue was parformed with the aid of X-ray micro-analyzer equipped with energy dispersive type detector. Aside from usual aboundant accumulation of particles in the alveolar macrophage, widespread uptake of lead particles was common findings in the epithelial cells cover-ing the bronchial tree as well as the alveolar surface. In the bronchial epithelium, particles were found more frequently in the periphery, especially in the terminal region, in which non-ciliated cells contained more numerous particles than ciliated epithelium. In the alveolar wall both the type I and type II alveolar epithelium contained lead particles. In every type of the above cells, phagosomes and lysosomes were the main site of localization of particles. Deformation and degradation of fume particles were conspicuous in the cytoplasm especially in the lysosomes and their in-tercellular biological solubilization were suggested. Significance of the above findings was discussed in relation to possible mechanisms of onset of cellular injury in the respiratory tract.
Particulate pollutants in urban air were collected on collodion membrane and thin metal film, and observed electronmicroscopically. Particles which took a jellied or greasy appearance and evaporated after exposure to electron beam on collodion mem-brane were noticed. On metal film, these jellied particles showed various appearances different from those on collodion membrane in consequence of an interaction between some components of particles and metal. Strong corrosiveness of jellied particles seen in summer may have some relation to the irritability of air pollutants to mucous membrane by air pollution.