210Po Activity in Pacific Oysters (Crassostrea gigas) from Quang Ninh, Vietnam: High Activity, Influencing Factor, and Health Risk Assessment.

This study evaluated 210Po activity and associated risk assessment in two organs of 20 Pacific oyster (Crassostrea gigas) groups (different sizes) collected at coastal areas of Quang Ninh, Vietnam. The elevated 210Po activity in hepatopancreas compared to muscle tissue, with mean values of 108 (53.4 ± 2.0 to 201 ± 12.1) and 15.7 (9.1 ± 0.4 to 26.3 ± 1.3) Bq/kg ww, respectively. The concentration factor (CF) in hepatopancreas (1.4 × 105) was significantly higher than that in muscle tissue (1.9 × 104), reflecting the preferential accumulation of 210Po in the digestive tract. There was the inverse coefficient relationship between shell length and weight with 210Po activity in muscle tissue, while no such correlation was found in hepatopancreas. Annual effective dose (AED) assessments showed that consumption of hepatopancreas far exceeded the reference value of 1 mSv/year, with mean values for adults, children, and infants of 1.35, 2.92, and 8.98 mSv/year, respectively. Meanwhile, the AED for muscle tissue was significantly lower, with mean AED values for adults, children, and infants being 0.20, 0.42, and 1.44 mSv/year, respectively. The total radiation dose to oysters ranged from 0.82 to 2.38 µGy/h, with a mean of 1.42 µGy/h, which is much lower than the ERICA reference threshold of 10 µGy/h, suggesting no significant risk to oyster population health. The study highlights specific recommendations to limit the consumption of oyster hepatopancreas, especially for sensitive populations such as children and infants, to minimize radiation exposure risk from oyster consumption.