In another report we described that a lot of dust raised at rapid heating of the coating materials of electrodes up to 300°C or 500-800°C. To know chemical changes in the component minerals of the coating materials and chemical substances scattered as dust during arc-welding, I examined by the x-ray diffraction coating materials of the electrodes, which had been rapidly heated to the temperatures of 100°C and over up to 1000°C at 100°C intervals respectively. Obtained results are as follows. 1) Although most component minerals of the coating materials suffered from no chemical change up to 600°C, complicated chemical substances began to be produced at 800°C. 2) The majority of components of dusts produced from the coating materials were in the state without chemical change, and only some of the dust components were the product of the thermal reaction. 3) It was considered that the irritation of the mucous membrane due to welding with a low hydrogen type electrode was not caused by fluorite, but by alkaline action of alkaline compounds and of dehydrated water glass. 4) Free silicates such as quartz and talc were included in the welding smoke. Therefore, it was considered that free silicates may have an important significance for producing the welder's lung.

View full abstract

Coating materials of three kinds of electrodes (low hydrogen type, lime titania type, and iron powder high iron oxide type) and the dusts emitted during the welding process were examined with X-ray diffractometry, polarization microscopy and chemical analysis. The results were as follows. 1) K⁺ions originating from potash water glass were found in the dusts from the low hydrogen type electrode. Its alkaline action seemed to cause irritations of the mucous membrane. A great portion of fluorine originating from fluorites was found as CaF₂ in the dusts from the low hydrogen type electrode. 2) Fine particles of quartz and talc were found in the dusts from either the lime titania type or the iron powder high iron oxide type electrode. 3) Iron oxide, mostly magnetite, occupied 30∼40% of the welding dusts. The authors should like to specify the welder's lung rather as a magnetite lung than an iron oxide pneumoconiosis.

View full abstract

An examination by a polarizing microscope of one case of welder's lung, in which free silica and silicates had not been detected by X-ray diffractometry, could defect quartz and talc particles in the lung tissue. Assuming from the results of a study on the baby powder affecting lungs of infants and school children, I estimated that the amounts of quartz and talc particles in the tissue of the welder's lung were 1.5 and 12 times the values of calculation respectively. The distribution curve of the particle size of free silica and silicates in the tissue of the welder's lung had two peaks. The particles were generally very fine. This fact agrees well with the experimental result that fine particles of free silica and silicates are emitted from the coating material of the electrode below 1, 000°C. After prolonged exposure to welding smoke from electrodes of ilmenite type, lime titania type, and high iron oxide type, this patient had a history also of exposure to the welding smoke from low hydrogen type electrodes. It can be considered that the alkali contained in this welding smoke promoted or accelerated the influence free silica and silicates in producing fibrosis. The fact that a large amount of free silica and silicates were observed around the wall of tuberculous foci, suggests the affinity between free silica or silicates and tuberculosis. As the welder's lung contains a large amounts of quartz and talc, it would be considered rather that these no doubt play an important part in producing fibrous changes than that only dusts of the oxides of iron are responsible. The extent of the fibrous change of the welder's lung did not depend upon the amount of the deposited dust suggesting the effect of the duration of exposure. The author should like to better specify the welder's lung as a magnetite lung than an iron oxide pneumoconiosis judging from the components of the welding dusts.

View full abstract