The consumption of plutonium, americium and radiocaesium in locally collected shellfish is an important contributor to the radiation dose received by seafood consumers living in West Cumbria. Only a small fraction of the actinide activity is assumed to be absorbed via the gut whilst it is assumed that all the radiocaesium is. Solubilization studies reported here using anin vitrodigestion method support the former assumption but not the latter, suggesting that the proportion of the137Cs available for absorption could be significantly smaller than unity where a large percentage of the ingested Cs is adsorbed onto inorganic sedimentary material. Such a situation arises near the Sellafield nuclear‐reprocessing plant where a high proportion of the radiocaesium (and plutonium) in the winkles collected locally and subsequently cooked is associated with inorganic particulate matter.