A new technique for generating heavy metal fumes with high melting point.
There are many kinds of fumes containing heavy metals in the working area. They sometimes have bad effects on the living body. It is important to determine their particle size distribution for considering the effects of those metals on health, together with measuring their amounts. For this purpose, it is neces-sary to generate fumes which are suitable to use. However, effective methods for generating fumes of heavy metals with high melting points have not been developed.In this study we attempted to determine whether the plasma flame metal sprayer can be used as a fume generator. The size distribution, particle form and amounts of the generated fumes were determined for the iron fume which were generated with this instrument under the various conditions. The fume was to consist of coagulated fine particles and dispersed globular particles. Our attempt extended to the generation of fumes consisting not only of one kind of metal but also of two kinds of metal. It was also found that fumes having the required radio might be generated by controlling the ratio of the metals in the powder mixture.We conclude that this instrument might be suitable for generating fumes of heavy metals in the laboratory.
Lung Lesions Nickel Fumes Induced by Intratracheal Instillation and Nickeloxide Powder in Rats of
Acute and subacute lung toxicity of nickel fumes was examined by single and repeated intratracheal instillation of nickel fumes and Ni203 and NiO powders in the rat. LD50 of nickel fumes was estimated as 38.2 mg/kg body weight (b.w.) according to the method of Litchfield and Wilcoxon. Body weight gain was retarded as in the order of a single dose of 13.0 mg Ni203/kg>14.3 mg nickel fumes/kg>1.4 mg Ni203/kg>13.0 mg Ni0/kg b.w. compared to controls. The histopathological changes in the lungs of the 14.3 mg nickel fumes/kg-dosed rats were milder than those induced by administration of 13.0 mg Ni203/kg but severer than those induced by administration of 1.4 mg Ni203/kg b.w. A single administration of NiO powder did not produce any histopathological effects on the lungs. The repeated administration of nickel fumes produced persistent edema and proteinosis in the alveoli. The nickel fumes, which were chemically composed of 97% of NiO and 3% of Ni203, were very fine particles about 5-10 nm in diameter, partly aggregated into larger particles and spherical particles about 0.6 ,um in diameter. Solubility in distilled water and saline was in the order of nickel fumes>Ni203 powder>>NiO powder. It was suggested that a toxic Ni203 component and very fine particles of nickel fumes are involved in the acute lung toxicity of nickel fumes. The epithelial injury induced by reactive oxygen and hydroxy radicals, which would be produced during the process of conversion of Ni(III) to Ni(II) and phagocytosis of nickel fumes by macrophages and polymorphonuclear cells, are presumed to be involved in the pathogenesis of nickel fumes-induced lung lesion.
Centrilobular emphysema experimentally induced by cadmium chloride aerosol.
Rats were exposed to a polydisperse aerosol of cadmium chloride solution for one hour on 5, 10, or 15 occasions. The animals developed acute vascular congestion and alveolar hemorrhage followed by polymorphonuclear cell infiltration. A granulation tissue response which tended to be localized around respiratory bronchioles subsequently occurred. By the tenth day after exposure, the granulation tissue had undergone rapid transformation to fine scar tissue with dilatation, distortion, and destruction of adjacent alveoli. The appearance of the lesions resembled human centrilobular emphysema. The severity of the emphysema as measured by the mean linear intercept method was related to the number of exposures to cadmium aerosol. Measurement of tissue cadmium confirmed accumulation of cadmium in the lungs of exposed animals; the concentration of cadmium was proportional to the number of exposures. It has been previously shown in autopsy studies that there is an increased cadmium content in the kidneys and livers ...