Exposure to low levels of ionizing radiation and lung cancer risk in Florida

The phosphate deposits of central Florida contain levels of uranium and its daughter products 30-60 times greater than average soils. A case-control study was conducted to assess the risk of lung cancer associated with living on these phosphateic soils. Using the records of the state-wide Florida Cancer Data System to address this issue, all cases of lung cancer among Florida residents in 1981 were identified (n = 7049). Information was obtained regarding residence, age, sex, race, and smoking habits. Controls consisted of 6643 individuals with cancers of the colon or rectum. Residents of the central Florida phosphate region experienced a significant increase in lung cancer risk compared to other Florida residents (odds ratio (OR) = 1.4). Excess risks appeared concentrated among squamous cell cancer (OR = 1.6) and small cell cancer (OR = 1.6). When smoking habits as well as residential area was considered, no significant excess risk, associated with residence, was observed among nonsmokers or light smokers. Area residents smoking a pack or more per day experienced a 70% increase in lung cancer risk compared to individuals smoking a similar amount but living elsewhere. Highest risks were observed among persons with squamous cell cancer (OR = 2.1) and small cell cancer (OR = 2.5) who smoked more than 40 cigarettes a day. Results suggest exposure to low levels of ionizing radiation increases the lung cancer risk of residents of this area