Pulmonary fibrosis of haematite miners

Abstract

In summing up the results of this investigation it is observed that the pulmonary fibrosis of haematite miners is a recent development. There is a history of haematite mining for several generations in this locality without any characteristic disability and yet within the last ten years a definite syndrome has developed which can be recognised clinically and which has an X..ray picture indicative of massive fibrosis.The post -mortem findings are peculiar to the occupation for the lungs present a definite series of characteristic changes, striking in appearance on account of the bright red colour of the fibrosed areas. The fibrosis is more marked in the upper lobes, is always diffuse and is often massive in type. It originates around the bronchi and blood vessels and gives excellent pictures of endarterit.i.s obliterans even when not, associated with tubercle.In the fifteen post -mortems, tubercle has been present in 66%. This is a higher percentage than is found in silicosis which has an average of only 56%. The experimental work confirms the general findings that infection is a necessary factor in the production of fibrosis and although two cases showed advanced fibrosis with no tubercle, this just means that tubercle is the most common infective agent, but other low grade infections can act as well. At a recent Meeting of the 1934 Commission investigating silicosis among coal miners, confirmation of this was found. It was observed that in mines where the men walked to the surface, there was only one quarter of the cases of silicosis compared with those where the miners were carried rapidly to the surface on trolleys. The latter caused chilling with increased liability to colds, bronchitis, and chronic Winter coughs with subsequent fibrosis.Chemical analysis of the lungs revealed a high silica content along with a phenomenally high per_ centage of iron in the ash. The ore analysed gave only a 10% silica content but as I pointed out the silica content of the dust whicb the men breathe is probably much higher.The appearance of this pulmonary siderosilicosis within recent years can only be attributed to the change in technique in mining for the ore has not changed chemically and the only difference is in the increased amount of dust in the mines. The modern method of mining with high speed percussion drills has considerably increased the amount of dust; this is lessened by the use of wet drills which, however, ¡increase the humidity and also increase the chance of infection as the miners have to work in wet clothing. The use of wet drills, while it slightly lessens the dust, does not restore working conditions to the old hammer and jumper standards for the increased amount of blasting and the shorter time the men are away from the working face results in their having to work longer in a dusty atmosphere.There can be no doubt that the disease has resulted directly from their employment and is caused by a combination of silica and haematite, the latter altering and aggravating the chemical action of the former, for in itself an ore containing only 10% of free and combined silica is not regarded as dangerous.It is considered that cases will not occur so frequently in the future now that the causes have been recognised, for the provision of proper ventilation after blasting, the use of wet drills and adequate supervision should be sufficient to ensure its prevention.