Variations of 210Po activity in mussel (Perna viridis) of Samut Sakhon and its contribution to dose assessment

Abstract

The activities of ²¹⁰Po and its effective dose in green mussel (Perna viridis) collected from a mussel farming area in Samut Sakhon province during the period of 20122013 are presented. Several parameters including maximum shell length and the physiological performance of mussels using condition index and physical properties of seawater (pH, salinity, conductivity, TDS, DO and cation-anion elements) were measured. Each individual mussel was measured for its maximum shell length which was adopted as size class. The activity concentration of ²¹⁰Po was determined spectroscopically through its 5.30 MeV alpha particle emission, using ²⁰⁹Po as an internal tracer. The ²¹⁰Po activity concentration in mussels was found to vary between 1.044 and 6.951 Bq/kg wet weight. The ²¹⁰Po concentration was higher in smaller-sized (≤35 mm) and lower in larger ones (40-70 mm). This confirmed that larger mussels have lower ²¹⁰Po activities on a weight basis. The ²¹⁰Po body burden (activity per mussel) ranged from 1.035 to 17.183 mBq. Contrary to the ²¹⁰Po concentrations, results of the body burden revealed the lower activities in smaller-sized mussels (≤35 mm) and the higher in larger-sized ones (40-70 mm). The type of fluctuations observed with ²¹⁰Po concentrations were interpreted as a seasonal effect. Total annual effective ²¹⁰Po dose due to mussel consumption was calculated to be in the range of 3.081 to 16.401 pSv. Based on the international guideline, the average dose calculated due to ²¹⁰Po in mussels of Samut Sakhon would not pose any significant radiological impact on human health and the mussels are considered to be safe for consumption.