A study of lung cancer and bronchitis mortality in relation to coal mining in Scotland

A retrospective mortality study of workers exposed to radon in a Brazilian underground coal mine

Recently a high radon concentration was detected in the underground coal mine of Figueira, located in the south of Brazil. This coal mine has been operating since 1942 without taking cognizance of the high radon environment. In order to assess possible radon-related health effects on the workers, a retrospective (1979-2002) mortality study of 2,856 Brazilian coal miners was conducted, with 2,024 underground workers potentially exposed to radon daughters. Standard mortality ratio (SMR) analysis hints at lower mortality from all causes for both underground (SMR = 88, 95% CI = 78-98) and surface workers (SMR = 96, 95% CI = 80-114). A high statistically significant SMR for lung cancer mortality was observed only in the underground miners (SMR = 173, 95% CI = 102-292), with a statistically significant trend reflecting the duration of underground work. High statistically significant SMRs were observed for pneumonia as a cause of death between both surface (SMR = 304, 95% CI = 126-730) and underground miners (SMR = 253, 95% CI = 140-457). Because mortality from smoking-related cancers other than lung cancer was not found elevated in underground workers and because diesel equipments were not used in this mine, it can be concluded that the enhanced lung cancer mortality observed for underground miners is associated with exposure to radon and radon daughters, rather than other confounding risk factors.

Mortality in gold and coal miners in Western Australia with special reference to lung cancer

Cohorts of 1974 gold miners and 213 coal miners in Western Australia surveyed for respiratory symptoms, smoking habits, occupational history and radiographic evidence of pneumoconiosis have been followed up for 13-14 years. Overall, neither group had a significantly higher mortality than expected from the experience of Western Australian men in general. Lung cancer mortality was relatively high in the gold miners (59 deaths observed, 40.8 expected) but weakly and inconclusively related to the extent of their underground mining experience. Cigarette smoking may explain the excess of lung cancer in the gold miners because the prevalence of the habit in the latter (66.3%) was higher than in the coal miners (58.7%) or in other men in Western Australia (53.2%). Radiographic evidence of silicosis was present in 21.7% of the gold miners but did not appear to have contributed substantially to their mortality. The coal miners showed a lower than expected rate of lung cancer but an excess of deaths from all other forms of cancer (11 observed, 5.6 expected). This excess was not attributable to any one cancer site and cannot be explained readily.