Abstract
PurposeRadiation dose estimates in epidemiology typically rely on intake predictions based on urine bioassay measurements. The purpose of this article is to compare the conventional dosimetric estimates for radiation epidemiology with the estimates based on additional post-mortem tissue radiochemical analysis results.MethodsThe comparison was performed on a unique group of 11 former Manhattan Project nuclear workers, who worked with plutonium in the 1940s, and voluntarily donated their bodies to the United States Transuranium and Uranium Registries.ResultsPost-mortem organ activities were predicted using different sets of urine data and compared to measured activities. Use of urinalysis data collected during the exposure periods overestimated the systemic (liver+skeleton) deposition of 239Pu by 155±134%, while the average bias from using post-exposure urinalyses was –4±50%. Committed effective doses estimated using early urine data differed from the best estimate by, on average, 196±193%; inclusion of follow-up urine measurements in analyses decreased the mean bias to 0.6±36.3%. Cumulative absorbed doses for the liver, red marrow, bone surface, and brain were calculated for the actual commitment period.ConclusionOn average, post-exposure urine bioassay results were in good agreement with post-mortem tissue analyses and were more reliable than results of urine bioassays collected during the exposure.
Highlights
Radiation epidemiological studies, such as the Million Persons Study [1,2] and International Nuclear Workers Study [3], typically rely on worksite records and bioassay measurements to estimate intakes, systemic deposition of radionuclides and, doses to the organs
Use of urinalysis data collected during the exposure periods overestimated the systemic deposition of 239Pu by 155±134%, while the average bias from using post-exposure urinalyses was –4±50%
Committed effective doses estimated using early urine data differed from the best estimate by, on average, 196±193%; inclusion of follow-up urine measurements in analyses decreased the mean bias to 0.6 ±36.3%
Summary
Radiation epidemiological studies, such as the Million Persons Study [1,2] and International Nuclear Workers Study [3], typically rely on worksite records and bioassay measurements to estimate intakes, systemic deposition of radionuclides and, doses to the organs. Bioassay measurements are often available only for a fraction of exposed workers, or the number of bioassay measurements is limited, and the samples are typically collected during the employment period as part of radiation protection monitoring programs [4,14]. The calculation of the organ doses from bioassay relies on the biokinetic and dosimetric models of the incorporated radionuclide. The accuracy of biokinetic models can and should be evaluated, for example, by using measured activities in organs and tissues of workers collected at autopsy
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