Polonium-210 contamination in marine bivalves from tropical coastal waters of Vietnam: Implications for environmental biomonitoring and ecological risk assessment.

Radionuclide pollution in the marine environment is becoming a growing concern because of its potential risks to human health and marine ecosystems. This study analyzed 210Po activity in two organs of 16 ecologically and economically important bivalve mollusk species at the tropical coastal area in Lam Dong, Vietnam, to evaluate their suitability for environmental biomonitoring and to assess ecological and radiological risks. The 210Po activity concentrations varied widely among species and organs, from 7.15 ± 1.3 to 212 ± 16 Bq/kg ww (mean: 58.9 Bq/kg ww) for muscle tissue, and from 44.2 ± 4.8 to 982 ± 89 Bq/kg ww (mean: 383 Bq/kg ww) in hepatopancreas. Mean concentration factors (CFs) of 3.38 × 104 (muscle) and 2.27 × 105 (hepatopancreas) exceeded the IAEA reference of 2 × 104, with hepatopancreas demonstrating superior potential as a sensitive biomarker minimizing the influence of biological, morphological, and analytical factors. Morphological and living behavior parameters showed no significant effect on 210Po accumulation. In all three consumption scenarios, the annual effective dose (AED) increased with decreasing age, indicating that infants were the most vulnerable population group. While the mean AED from muscle tissue consumption remained below the recommended limit of 1 mSv/year for adults, whole-body tissue consumption exceeded this limit across all age groups, and hepatopancreas-only consumption represented the highest exposure scenario. Ecological risk assessment using the ERICA Tool showed that 2/16 species exceeded the screening threshold of 10 μGy/h, highlighting the need for further site-specific ecological risk assessments and long-term monitoring. These findings provide a scientific baseline data for developing age-based consumption guidelines and comprehensive radiation risk assessments in the future.