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.
Hexavalent chromium responsible for lung lesions induced by intratracheal instillation of chromium fumes in rats.
Lung toxicity of chromium fumes (Cr fumes) was examined by a single intratracheal instillation into rats of 10.6 mg and 21.3 mg Cr fumes/kg body weight and by repeated (3 times) instillations of 10.8 mg and 21.7 mg Cr fumes/kg. The pathological changes were compared with those induced by single administrations of 3.2 mg and 19.2 mg Na2CO3 solution-insoluble fraction of Cr fumes (Cr-Fr)/kg and 20.8 mg commercially available chromium (III) oxide powder (Cr (III) oxide)/kg. Single and repeated administrations of Cr fumes suppressed growth rate in a dose-dependent manner, but administrations of Cr-Fr and Cr (III) oxide did not. A single administration of Cr fumes produced granulomas in the entire airways and alveoli with progressive fibrotic changes, as well as severe mobilization and destruction of macrophages and foamy cells. Those histopathological changes were aggravated by the repeated administration of Cr fumes. On the other hand, single administrations of Cr-Fr and Cr (III) oxide produced no remarkable histopathological changes. Cr fumes were found to be composed of 73.5% chromium (III) oxide and 26.5% chromium (VI) oxide. The primary particles of Cr fumes and Cr-Fr were similar, 0.02 micron in size (sigma g: 1.25), and Cr (III) oxide particles were 0.30 micron in size (sigma g: 1.53), measured by analytical electron microscopy (ATEM). Diffuse clusters of the primary particles in Cr fumes were identified as Cr (VI) oxide. The present results suggested that the lung toxicity of Cr fumes was mainly caused by these Cr (VI) oxide (CrO3) particles in Cr fumes.
Inhaled Particles. III
master the theory of first-order linear differ tions. Those who ale not will find little to he treatment throughout is in terms of first-ord There is no attempt to follow up, for examp of Hartley (J. theor. Biol., 5, 57, 1963) or Mann, and Lieberman (J. clin. Endocrinoi 1963) which could lead to treatments req elementary mathematics. For those with n knowledge the treatment is inadequate. A Si of cases are treated in great detail; there is li of non-linear processes; and what there is, not related to any fundamental processes at trary to the suggestion in 'Final Remarks', a] be better off using a book on tracer kin relevant mathematics. The use of the kinetio olism after a single exposure to calculate tI multiple exposure is theoretically sound bu dubious, owing to the difficulty of measuring after single exposure accurately enough. The author does make the valid point that tions underlying tracer and toxicological ii are often different, even when the matt identical, and the main value of the book 1 cussion of the assumptions involved in the la brings together much data published onl European languages and therefore rather here.