No abstract

This paper summarises a comprehensive review of radio-analytical data from autopsy, whole or partial body monitoring and the assay of teeth, foetuses and urine for non-occupationally exposed members of the public in the UK between 1957 and 2003. Most attention has been given to measurements of artificial radionuclides formed in the nuclear fuel cycle, uranium and thorium. The review concentrates on measurements on people in the UK who live or have lived in the vicinity of nuclear power sites. When UK data are unavailable, or for the purposes of comparison, information has been included from studies in other countries. Highlights of key findings of the document are listed: The concentrations of strontium-90 in bone and teeth have reflected changes in the amounts present in the environment due to fallout from nuclear testing. There are higher concentration levels of 239+240Pu in samples from West Cumbria compared with the rest of the UK. However, the levels are so low that any increase in risk of induced skeletal tumours (including leukaemia) would be very small compared with those arising from the intake of natural radionuclides. As expected there have been only a few published autopsy studies. Both tissue sample mass and radionuclide concentrations were low, leading to relatively large measurement uncertainties. Whole body measurements of 137Cs in residents in Berkshire and Oxfordshire clearly show the effect of atmospheric testing of nuclear weapons and of the Chernobyl accident. A survey of whole body 137Cs and 134Cs content following the Chernobyl accident showed that residents of Central Scotland, North-West England and North Wales had twice the radiocaesium content of residents in the rest of England and Wales. Measurements of 131I in the thyroid have been reported following the accidents at Windscale and Chernobyl for most regions of the UK. Few excretion studies have been reported although this does not diminish their importance. One study on the urinary excretion rate of 90Sr in adults and children living in the Dounreay area suggested that the results did not support this radionuclide as being the cause of increased childhood leukaemia. Similar conclusions were drawn from another study involving the assay of 239Pu. It is suggested that a national database of measurements made on members of the public should be initiated. The database would provide a means for identifying future trends.

No abstract

With the experimental evolution of fusion power the levels of tritium used will increase as will the potential for human exposure. Tritium-loaded carbon particles produced during the experimental operation of the Joint European Torus fusion tokamak have been characterised in terms of size, elemental composition and specific activity of tritium elsewhere. The aim of this study was to characterise the dissolution of tritium from these particles in order to derive dose coefficients for this material and provide guidance on monitoring procedures should it be inhaled accidentally. The dissolution of tritium was measured for 100 d in lung serum simulant from two batches of materials, SG1 and SG2, which were obtained from carbon tiles originating from different positions in the reactor. Retention over this period followed a three-component exponential. About 1-5% dissolved within a minute, and up to a further 20% dissolved over 100 d for the SG1 materials but <1% for the SG2 materials. Dissolution between the SG1 materials varied greatly, whereas the SG2 materials were similar. As a result of this variability, the assessed dose from urinary excretion could be in error by up to two orders of magnitude depending on the material inhaled. It is recommended that (i) the dissolution is measured for a wider range of materials, preferably dusts collected in working areas, and (ii) in vivo studies are performed to characterise fully the urine excretion of tritium from these materials. This information could be used to provide improved guidance on dose assessment after special or routine monitoring, taking account of the likely variation of particle size and biological retention half times.

The aim of this work was to investigate the biokinetics of thorium dioxide in animals for the purpose of assessing intakes of the compound by workers and the resulting doses. The results imply that measurements of the decay products in the chest or extrapolations from urine analysis data are unlikely to be of value for doses below 20 mSv. Even higher doses should be interpreted with caution as a consequence of uncertainties in particle size distribution and variations in dietary excretion.