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This paper briefly reviews the contributions made by human tissue studies to improved understanding of the biokinetics, dosimetry and potential bioeffects of plutonium in man. It includes consideration of tissue donations from both environmental and occupational populations, along with a brief history of human experience with plutonium and consideration of the bioethical aspects of post-mortem human tissue sampling.

The placenta and umbilical cord were obtained following a normal live delivery from a volunteer donor who had received an accidental inhalation intake of plutonium 12 years prior to her pregnancy (Case 0777). Her employer estimated the intake to be about 73 Bq Class W plutonium. Based on bioassay results and clearance models in use at that time, they calculated her body content at the beginning of pregnancy to be about 5.6 Bq with an average concentration of approximately 60 mBq kg(-1). The placenta and cord from this pregnancy, along with the placenta and cord from a donor with no known exposure to plutonium (Case 0835), were divided and assayed for plutonium by ultrasensitive fission track analysis at two collaborating laboratories. Placental 239Pu concentration values obtained by the two laboratories for Case 0777 agreed within a factor of 2 and were several-fold greater than for the control, Case 0835, as well as values that had been reported by others for unexposed populations. There was no elevated concentration of plutonium in the umbilical cord from the exposed person. The data yielded values of 0.16 and 0.27 for placental to maternal concentrations (CPl: CM) that were of the same order of magnitude as the value of 0.1 the ICRP calculated for intakes before pregnancy.

The utility and even the validity of radiation epidemiology studies rest upon the quality of the underlying radiologic data and the correctness of their interpretation. To ensure meaningful and comparable results, radioepidemiologic studies need to properly and consistently use radiologic quantities and units, and to evaluate and fully discuss the radiologic measurements and their interpretation, recognizing that experts in health physics may differ in their assessments. As succinctly stated by Polya Two persons presented with the same evidence and applying the same patterns of plausible inference may honestly disagree.