²¹⁰Po and ²¹⁰Pb activity concentrations in Greenlandic seabirds and dose assessment

Naturally occurring radionuclides, in particular, polonium-210 (²¹⁰Po), have a greater contribution than anthropogenic radionuclides to the annual effective dose received by the general public due to consumption of seafood. Knowledge of potential trophic sources and transfer of ²¹⁰Po to seabird species and subsequently to the Greenlandic people is, however, still poor. Here, we assess the transfer of ²¹⁰Po and ²¹⁰Pb to seabirds sampled during autumn and winter 2017 and 2018 in Greenland and provide a dose assessment. The activity concentrations of ²¹⁰Po in muscle and liver, respectively, ranged from 0.2 ± 0.1 Bq kg^-1 w.w. in glaucous gull (Larus hyperboreus) to 21.2 ± 22.6 Bq kg^-1 w.w. in thick-billed murre (Uria lomvia) and from 32.0 ± 9.4 Bq kg^-1 w.w. in common eider (Somateria mollissima) to 40.5 ± 49.0 Bq kg^-1 w.w. in thick-billed murre. ²¹⁰Po was non-uniformly distributed in the body of thick-billed murre. Kidneys and feathers showed higher ²¹⁰Po activity concentrations than heart and bone. The ²¹⁰Po/²¹⁰Pb activity concentration ratios are higher than unity, indicating that ²¹⁰Po is preferentially taken up by seabirds compared to its progenitor ²¹⁰Pb. The derived annual absorbed dose from ²¹⁰Po to the whole body of thick-billed murre was 6.4 × 10² ± 3.0 × 10² μGy. The annual effective dose to the average adult and representative person in Greenland due to ingestion of ²¹⁰Po in seabirds was estimated to 13.0 μSv and 57.0 μSv, respectively. This derived dose is low and poses a slight risk, and risk communication is therefore deemed unnecessary.