Pinney's team conducted a four-year study, based on questionnaire information about actual work location and the time of work shifts, to determine how much radon workers from different areas of the plant were exposed to.
Fernald personnel records did not include work locations, so to accurately evaluate radon exposure levels the UC researchers developed a complex worker-location coding system to place employees at specific sites across the plant. They also used a specialized plastic film to measure radon exposure at the various plant locations. By studying the number of tracks left on the film by radon decay products, they found the second radon source.
"Radon gas disperses widely," explains Pinney, "and since the level of radon exposure is based on your proximity to a specific source, we had to know approximately where each worker stood or sat during their shift to figure out what level of radon they were being exposed to."
Pinney's team divided the 1,000-acre Fernald facility into numerous work locations within areas of the facility: the "production area," which included all production plants and outlying buildings; "controlled production areas" other non-production areas where workers were also required to undergo decontamination measures; and "uncontrolled areas," which included common destinations such as the cafeteria, administrative offices, laundry and laboratories. Employees were further differentiated into 41 categories based on what years and shifts they worked in the plant.
Using information from individual worker's job history files, the team was able to assign workers to locations across the plant, for each calendar year. Worker locations were verified using data from more than 2,100 detailed questionnaires completed by employees enrolled in the plant's medical monitoring program.
"Although we can't determine the exact number," says Hornung, "our research suggests that over 2,500 peop
|Contact: Amanda Harper|
University of Cincinnati