Studies of underground miners have documented an increased risk of lung cancer mainly linked to radon exposure but possibly influenced by other concurrent exposures.
A cohort study was carried out in 8321 iron ore miners with low exposure to radon, employed in 1923-1998 and followed up for lung cancer in 1958-2000. Historical exposures to radon, crystalline silica and diesel exhaust were assessed. Data including exposure to radon, quartz and diesel exhaust from another mine with higher exposure to radon were reanalysed.
Miners had increased risk for lung cancer (SIR 1.48 (95% CI 1.22 to 1.78), based on 112 cases during 227,000 person-years). The increased risk could not be explained by exposure to radon or diesel exhaust but was associated with exposure to crystalline silica: SIR 0.96 (0.53 to 1.62), 1.45 (1.10 to 1.87), 1.99 (1.31 to 2.90) and 1.77 (0.92 to 3.10) in groups with exposure to 0, 0-2, 2-5 and >5 mg years/m3, respectively. Reanalysis of data from the other mine indicated that quartz was a possible confounder in the analysis of relationship between radon and lung cancer. In the highest radon exposed group, the point estimate for the RR decreased from 5.65 to 3.90 when adjusting for concurrent exposure to quartz.
Crystalline silica, a known carcinogen, probably affects lung cancer risk in iron ore miners. The main implication of the results is for interpretation of the dose-response curve for radon and lung cancer in underground iron ore miners. Since exposure to radon and quartz is often correlated, quartz exposure can be an important confounder.
This is a population-based study on the prevalence of respiratory symptoms assessed by a mail questionnaire. The objective was to examine if work in an iron mine increased the risk of airway symptoms or obstructive diseases. The exposed group consisted of 114 previous or current male miners. Referents, 2472 males from the province, had never been employed by the mining company or worked as miners. Age, smoking and a family history of asthma were considered as possible confounders. The miners had an increased risk for respiratory symptoms (OR=2.2, 95% CI=1.4-3.1) including recurrent wheeze (OR= 2.4, 95% CI= 1.5-3.9), longstanding cough (OR= 1.8, 95% CI = 1.0-3.2), and for physician-diagnosed chronic bronchitis (OR=2.2, 95% CI= 1.0-4.5). Attacks of shortness of breath and asthma manifestations were similar between miners and referents. Higher risks in miners were found particularly among the non-smokers for physician-diagnosed chronic bronchitis (OR=9.2, 95% CI= 3.0-28) and for symptoms as well. A family history of asthma was less common among miners (9.2% vs. 17%, p
Many measures have been taken in Sweden to eliminate the occurrence of serious silicosis. However, between 1997 and 2013 there were 111 deaths with silicosis as underlying cause, 110 men and 1 woman. In most cases the deceased was rather old; only fourteen persons were below 74 years of age. We have studied the exposure between 2007 and 2012 in the 71 persons who died of silicosis as underlying or contributing cause through medical records. We could find information regarding 48 of them. Ten persons worked in mines, 10 in stone industry, 14 with crushing or blasting of rock, 4 in foundries, 3 were concrete workers and 7 suffered exposure in other industries. The study shows that the measures taken in Sweden have not been sufficient to totally eliminate serious silicosis.