Abstract

Boyd, J. T., Doll, R., Faulds, J. S., and Leiper, J.(1970).Brit. J. industr. Med.,27, 97-105. Cancer of the lung in iron ore (haematite) miners. The mortality of Cumberland iron-ore miners has been studied by examining the death certificates of 5 811 men resident in two local authority areas (Ennerdale R.D. and Whitehaven M.B.) who died between 1948 and 1967. Comparison of the iron miners' experience with (1) that of other local men and (2) the relevant national experience has provided an assessment of the suspected occupational risk of lung cancer associated with haematite mining. During the 20-year period there were 42 deaths attributed to lung cancer among iron mine employees resident in the study area: 36 of these occurred in miners working underground, which was significantly greater than that expected from local non-mining (20·6 deaths) or national (21·5 deaths) experience. In contrast to these findings, there was no evidence of any excess mortality from lung cancer among surface workers and, for iron miners as a whole, mortality from other cancers was close to the national experience. A parallel analysis of mortality among coal miners showed a deficit of deaths from lung cancer in line with other studies. The patterns of other respiratory mortality in the two local mining groups were also in line with previous experience, and confirmed the existence of a substantial silicotic hazard associated with haematite mining in Cumberland.

These findings strengthen previous necropsy evidence and indicate that West Cumberland iron-ore miners who work underground experience an occupational hazard of lung cancer. They suggest that the miners suffer a lung cancer mortality about 70% higher than `normal'. The risk may be due to radioactivity in the air of the mines (average radon concentration of 100 p Ci/litre) or to a carcinogenic effect of iron oxide.