NRPB - W51 UK Assessment of Intake and Dose after Inhalation of Caesium-137 by Workers and Adult Members of the Public

Synopsis

For the assessment of intake and dose of inhaled caesium-137 compounds, it is usually assumed that the absorption parameter values conform to those for default Type F and that the whole body retention half-time is 110 days, as recommended by the International Commission on Radiological Protection (ICRP). This report considers the impact of the variation of published whole body retention half-times that range mostly between 50 and 150 days, and absorption parameter values which include the ICRP defaults for Types F and M and data obtained for an industrial dust obtained from a nuclear power plant. The data are presented for repeated and acute intakes of all three types of material by workers and for default Type F caesium compounds by members of the public.

It is concluded that both whole body monitoring and urine assay can be used with advantage to confirm annual doses below 1 mSv, even when whole body retention half-times and absorption parameter values are highly variable. However, in order to reduce uncertainties in assessed intake and dose, experimental evidence should be available or expert judgements made on the in-vivo dissolution characteristics of caesium-137. Moreover, when urine analysis is used to assess intake and dose, excretion from dietary intake should be confirmed as low when compared with the predicted rate after inhalation.

Last reviewed: 27 August 2009