Evaluation of heavy metals and radionuclides in fish and seafood products

Despite the existence of a legislation regarding food contaminants, food safety control in Serbia is a matter of great concern. This study investigates the radioactivity levels and heavy metal concentrations in fish and seafood commercially available in Serbian markets. Domestic fish species (caught in the Danube River) and fishery products imported from Europe, Asia and America were analyzed. The content of natural radionuclides and ¹³⁷Cs were investigated by gamma spectrometry. Activity concentration of ⁴⁰ K was measured in the range of 44-165 Bq kg^-1; low levels of ¹³⁷Cs were detected in two samples (2.8 and 3.0 Bq kg^-1), while concentrations of ²²⁶Ra and ²³²Th were below minimal detectable values. Concentrations of heavy metals (Cd, Hg and Pb) were determined using ICP-OES method. Cd concentration ranged from 0.01 to 0.81 mg kg^-1 in sea fish and from 0.01 to 0.03 mg kg^-1 in freshwater fish. Hg concentrations were in the range of 0.01-1.47 mg kg^-1; the highest value was measured in the predator fish - shark. The highest level of Pb (6.56 mg kg^-1) was detected in a blue sea fish (Atlantic mackerel). The health risks associated with the intake of heavy metals and radionuclides via fish consumption were evaluated. The results indicate that fish and seafood consumption do not pose a significant health concern in the case of the usual consumption rate which is typical for the population of Serbia. However, a highly frequent consumption of fishery products can have adverse health effects, especially due to Hg and Pb contamination.