Despite being one of the most expensive gourmet foods, it remains unclear if the iconic White Truffle (Tuber magnatum Pico; hereinafter WT) accumulates radioactivity at harmful levels comparable to other fungal species. Here, we measure the active radiocaesium-137 concentration (137Cs) in ten hypogeous WT fruitbodies from southern Hungary, and the soils in which they were growing. All WTs reveal non-significant 137Cs values, thus providing an 'all clear' for WT hunters in the species' northernmost habitats, where corresponding soil samples occasionally exhibit slight 137Cs concentrations. Our results are particularly relevant in the light of a rapidly increasing global demand for WTs and their subsequent trading extent and price inflation, because up to 600 kg of fresh fruitbodies are harvested each year in southern Hungary. Moreover, some of Europe's forest ecosystems, in which mushroom picking is common practise, are still contaminated with 137Cs from the Chernobyl fallout more than 30 years ago, posing a serious threat to human health.

Department of Geography University of Cambridge Downing Place CB2 3EN UK; Department of Physical Geography Stockholm University SE 10691 Stockholm Sweden

Department of Geography University of Cambridge Downing Place CB2 3EN UK; Swiss Federal Research Institute WSL Zürcherstr 111 8903 Birmensdorf Switzerland; Global Change Research Centre Bělidla 986 4a Brno 603 00 Brno Czech Republic; Department of Geography Faculty of Science Masaryk University Kotlářská 2 613 00 Brno Czech Republic

NEFAG Zrt Kaán Károly u 71 7000 Szolnok Hungary

Paul Scherer Institute PSI Forschungsstr 111 5232 Villigen Switzerland

Swiss Federal Research Institute WSL Zürcherstr 111 8903 Birmensdorf Switzerland

References provided by Crossref.org

Sustainable cultivation of the white truffle (Tuber magnatum) requires ecological understanding