Radon Exposure to Community Members Living Near a Uranium Procession Plant

Abstract

Background: Members of the Fernald Community Cohort (FCC, N=9782) are persons who lived within 5 miles of the uranium processing plant at Fernald, Ohio, USA. From 1951 to 1989 the site processed uranium ore and recycled materials to make highly refined uranium metal products used in the United States Department of Energy nuclear weapons production. The aqueous raffinate or waste from the chemical digestion process was pumped into two large concrete silos for storage and were found to be sources of radon decay products. Vents in the protective dome covers were not sealed until 1979. Source terms and dosimetry algorithms for exposure to both uranium particulates and radon were developed by CDC. Methods: Based on the CDC prior work, we developed a mathematical model to estimate yearly outdoor radon exposure persons in the cohort from the K-65 silos during 1952-1988. We collected and verified residential history information from members of the cohort. We used the radon source terms developed by CDC, yearly wind speed and direction data, and applied the model to the residential history for each member of the cohort. Results: 9306 members of the cohort had sufficient residential history information to be used for radon dosimetry calculations for individual cohort members. The population mean value (sd) of total cumulative exposure (over the years 1952-1988) was 460.70 (508.84) pCi/m2-years, median 299.60 pCi/m2-years, with a large range of 0-4625.75 pCi/m2-years. Arithmetic median exposure also was calculated for each person, or the median of yearly exposure, with a population mean of 20.43 pCi/m2, also with a large range 0 to 200.57 pCi/m2. Conclusions: Using reliable data and well-developed algorithms we estimated environmental (outdoor) radon exposure for members of the FCC and found a wide range of cumulative outdoor radon exposure. Key Words: uranium, radon, community cohort