Radiometric analysis of farmed fish (sea bass, gilthead bream, and rainbow trout) from Tenerife Island, Spain.

This study analyzed the content of gamma-emitting radionuclides in fish farmed on the island of Tenerife (Canary Islands, Spain). The fish species included in this study were sea bass, gilthead bream, and rainbow trout. The first two species are produced in offshore enclosures, while the third is produced in a freshwater fish farm. All measurements were performed using two high-purity germanium gamma-ray detectors. The content of gamma-emitting radionuclides in the fodder used to feed the different species of farmed fish studied was also determined. The following nuclides were often detected in the analyzed samples: 137 Cs, 40 K, 235 U, 228 Ac, 214 Bi, 208 TI, 212 Pb, and 214 Pb. As a complement to this analysis, 210 Po concentrations in two fish samples were determined by alpha spectrometry. The nuclide presenting the highest concentration was, as expected, the naturally occurring 4o K, with an average concentration of 0.13 ± 0.01 Bq/g (wet weight) (Bq/gww) in gilthead bream and sea bass and 0.12 ± 0.01 Bq/gww in rainbow trout. The 235 U concentrations determined in the same fish species were 0.6 ± 0.5, 0.8 ± 0.7, and 1.6 ± 1.0 mBq/gww, respectively. This nuclide is seldom reported in fish samples. The concentrations of 137 Cs (the only artificial nuclide determined in this study) in gilthead bream and sea bass were 0.026 ± 0.006 and 0.044 ± 0.01 mBq/gww, respectively. In addition to the radiometric analysis, the contribution of the analyzed nuclides to the effective dose from the mean daily intake of the fish was calculated. The calculated contribution, in terms of dose per person, produced by intake of the analyzed fish was 0.8 μSv/year. This value does not represent a significant risk to the local population.