Radioactive Ore
The increased incidence of lung carcinoma in miners of radioactive ore was first noticed in Central Europe. The time from onset of exposure to development of lung carcinoma is approximately twenty years. In the United States, analysis of workers from colorado uranium mines and in Canadian uranium mines in Newfoundland have also shown a significant increased risk of developing lung carcinoma. Both the United states and Canadian sites have a high level of contamination with radon daughters, which are a natural decay product of uranium. The pathology of radiation associated lung cancers has been well studied and small cell carcinoma predominates. Cigarette smoking synergistically increases the risk of developing lung carcinoma. However, studies of non-smoking Navajo Indians who worked on the Colorado Plateau also have a significant increased risk for lung cancer over the normal population.