Can default ICRP f1 values be applied to determine radiation dose from the intake of diet-incorporated thorium?

Data on the daily urinary excretion of thorium (Th) was obtained from 15 non-exposed adult German subjects. A radiochemical neutron activation analysis method was developed and standardised especially for this purpose. The daily urinary excretion of 232Th was found to be in the range 1.9-14.9 microBq d(-1) with a mean (+/-SD) value of 6.5 (+/-4.3) microBq d(-1). Using this excretion value and reported data on dietary intake of Th for a similar German population, the gastrointestinal absorption factor (f1 value) proposed by the International Commission on Radiological Protection (ICRP) was tested. Although the daily excretion of 232Th observed in the present study was comparable to some of the currently reported values in certain other countries, it was higher than the excretion value calculated by applying the biokinetic model of Th proposed by ICRP for the dietary intake values. The study showed that the default ICRP values of the f1 factor for diet-incorporated Th may not be applicable.

Strontium biokinetics in humans: influence of alginate on the uptake of ingested strontium.

Radioactive isotopes of strontium, mainly 90Sr, released into the environment due to nuclear accidents may contribute significantly to the internal radiation exposure of members of the public after ingestion of strontium with contaminated foodstuffs. The committed radiation dose is significantly dependent on the fraction of the ingested activity that crossed the gut wall (f1 value). In tracer kinetic investigations, the effect of sodium alginate on the gastrointestinal absorption of strontium was studied in human subjects. Sodium alginate was proven to be a potent agent for reducing strontium absorption with high efficiency and virtually no toxicity. The data obtained show that the uptake of ingested strontium from milk was reduced by a factor of nine when alginate was added to milk. It is concluded that alginate preparations are a suitable antidote against radiostrontium.