Uncertainty on faecal analysis on dose assessment

Monitoring programmes for internal dose assessment may need to have a combination of bioassay techniques, e.g. urine and faecal analysis, especially in workplaces where compounds of different solubilities are handled and also in cases of accidental intakes. Faecal analysis may be an important data for assessment of committed effective dose due to exposure to insoluble compounds, since the activity excreted by urine may not be detectable, unless a very sensitive measurement system is available. This paper discusses the variability of the daily faecal excretion based on data from just one daily collection; collection during three consecutive days: samples analysed individually and samples analysed as a pool. The results suggest that just 1 d collection is not appropriate for dose assessment, since the 24 h uranium excretion may vary by a factor of 40. On the basis of this analysis, the recommendation should be faecal collection during three consecutive days, and samples analysed as a pool, it is more economic and faster.