Can cooking practices affect dietary exposure to 210Po in seafood?

Abstract

Background: The estimated yearly worldwide average exposure to radiation is about three mSv, with 2.4 mSv coming from natural radiation sources. 210Po is a highly radiotoxic decay product of 238U and a major contributor to internal radiation dose in humans, especially from seafood consumption. Swedish dietary guidelines recommend frequent seafood consumption, and thus, monitoring 210Po levels is important due to significant dose contributions and lack of guidelines on intake restrictions. Studies show that the Swedish population's yearly average radiation dose from seafood is about 100 μSv, with high consumption groups receiving above 500 μSv for children and 300 μSv for adults. The choice of method to cook seafood can influence the 210Po levels, which impacts the dose assessments from seafood ingestion. Aim: The aim of this master thesis was to determine the impact of cooking on the activity concentration of 210Po in seafood, and to calculate a committed effective dose to humans for consumption of seafood purchased in Sweden. Method: Blue mussels and Norwegian lobsters were bought from selected fish stores in Gothenburg, Sweden. Blue mussels were cooked by boiling, steaming, roasting, or by heating in a microwave. Norwegian lobsters were cooked by boiling, steaming, roasting, or pan-frying. 210Po in blue mussels and Norwegian lobsters was separated using a radiochemical separation method and then measured using alpha spectrometry. The committed effective dose per kg of blue mussels or Norwegian lobster tail meat for an adult was calculated based on the activity concentration of 210Po measured in said seafood. Results: The activity concentration of 210Po varied by cooking method for mussels and lobster. For raw mussels, the average committed effective dose was 44 ± 6 μSv per edible kg, and for boiled mussels 68 ± 8 μSv per edible kg. For raw lobster tail, the committed effective dose ranged from 3.1 ± 1.1 μSv per edible kg to an average of 5 ± 1 μSv per edible kg. The higher doses are likely due to the water content lost during cooking. Discussion and Conclusion: The study observed some variation in 210Po activity concentrations between replicates for blue mussels and Norwegian lobsters for all cooking methods. Raw blue mussels had 210Po levels consistent with previous studies, but more replicates are needed for greater accuracy and to compare different cooking methods. Boiling transferred more of 210Po to the water compared to steaming. Future studies should include more replicates and study e.g., how cooking time affects the activity concentration of 210Po.