Radiocaesium activity concentrations in macrofungi from Galicia (NW Spain): Influence of environmental and genetic factors.

Radiocaesium ((137)Cs) is an artificial radionuclide that can be captured from the soil through the mycelium of fungi. However, in Spain there are few data on its presence in edible mushrooms. (137)Cs activity concentrations were determined using 54 samples of wild and cultivated mushrooms and 18 samples of soil, all of them collected in Galicia (NW Spain) during 2010. Samples were analyzed by gamma spectroscopy with a High-Purity Germanium (HPGe) detector. The average activity concentration of (137)Cs in wild mushrooms was 249.2Bqkg(-1) dry weight (dw) and about 24.9Bqkg(-1) fresh weight (fw). Genetic factors (species) influenced the uptake of (137)Cs, highlighting Hydnum repandum as the greatest accumulator of all wild species (1016.4Bqkg(-1) dw), while cultivated species showed much lower levels (1.6Bqkg(-1) fw). Accumulation was also favored by fungal mycorrhizal ecology, whose mycelium was distributed in contaminated soil horizons. The mean levels detected in soils were 14Bqkg(-1) fw. Although some species behaved as bioexclusors of radiocaesium, the transfer factors (TF) suggest that mushrooms preferentially bioaccumulate (137)Cs. No sample reached the limit of 600Bqkg(-1) fw (about 6000Bqkg(-1) dw) indicated in the European legislation. In conclusion, the consumption of mushrooms harvested from the investigated areas poses no toxicological risk to human health due to radiocaesium.
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