Dosimetric implications of human ingestion of the natural radionuclide polonium-210 from commercially important and edible seaweeds

Natural polonium has been identified as the largest effective radiation dose contributor from seafood consumption. The global seaweed industry has expanded significantly in recent years and seaweeds are now used in a wide variety of food and nutritional products. However, relatively few data exist on the accumulation of ²¹⁰Po by seaweeds. This study investigated ²¹⁰Po concentrations in twelve commercially important and widely consumed seaweeds from the Irish Sea and North-East Atlantic Ocean, six of which have not previously been reported. Polonium-210 was determined by radiochemical separation and high-resolution alpha spectrometry, with activity concentrations of other natural radionuclides (⁴⁰K, ²¹⁰Pb, ²²⁶Ra, ²²⁸Ra, ²³⁸U) determined via high-resolution gamma spectrometry. Polonium-210 concentrations were typically larger in red seaweeds compared to brown species. Ascophyllum nodosum had the lowest concentration of ²¹⁰Po, while Osmundia pinnatifida had the greatest. The concentrations factors of ²¹⁰Po ranged from 7.3 × 10³ to 71.3 × 10³ in the seaweeds examined. The annual consumption dose from edible seaweeds was estimated as 1.7 μSv for a typical consumer and 6.4 μSv for a heavy consumer. These values are significantly lower than the global estimated annual average ²¹⁰Po ingestion dose of 70 μSv and, hence, pose no significant radiological risk. This study provides new findings for ²¹⁰Po activity concentrations and concentration factors in a range of seaweeds from the North-East Atlantic and the Irish Sea, and establishes an updated assessment of the ingestion dose contribution for ²¹⁰Po and other naturally-occurring radionuclides from the consumption of edible seaweeds.