Dietary exposure to thallium from various species of Asian wild edible mushrooms.

The health risk from thallium (Tl) exposure through the consumption of edible wild mushrooms was investigated. Eight popular wild Asian species were determined for Tl content in raw and stir-fried composite samples, using validated analytical methods and measurement by ICP-MS. Wet weight thallium concentrations, ranged from 2.5 μg·kg-1 in stir-fried Butyriboletus roseoflavus and Scleroderma yunnanense to 20.0 μg·kg-1 in Termitomyces eurrhizus (median and mean values were 2.7 and 7.9 μg·kg-1). Stir-frying resulted in Tl enrichment (+13 to +130%) compared to raw mushrooms because of biomass shrinkage and partial retention of metallic constituents. The non-carcinogenic health risk from Tl through consumption was estimated using both, the Hazard Quotient (H; values >1 indicate a risk) as well as the Upper Intake (UI) level of 0.02 μg·kg-1 bw per day. At the same portion sizes of 100 g, fried samples of B. roseoflavus, C. cibarius, R. virescens and S. yunnanense showed lower risk with H quotient values below 1.0. Conversely, B. bainiugan and T. eurrhizus showed high H values of 3.0 and 3.3. At larger portion size of 300 g (not unusual for some remote Asian ethnic communities), all species showed H quotient values >1. This varying species-dependant risk was reflected when evaluated against the UI level with B. bainiugan and T. eurrhizus, both exceeding the UI-level by 1.6 times. In more remote communities where foraged wild mushrooms constitute a significant dietary component, Tl could potentially be considered as a toxicant when consumed in relatively larger amounts or if a particular species showed high concentrations.