Health risk assessment of toxic metals and toxigenic fungi in commercial herbal tea samples from Belgrade, Serbia

This study aimed to: (i) determine the content of toxic metals and toxigenic fungi in 14 commercial herbal tea samples from the market of Belgrade, Serbia; and (ii) assess their risk to human health. After the microwave digestion (HNO3/H2O2, 7:1,v/v), toxic metal content was determined by graphite furnace atomic absorption spectroscopy (GF-AAS). The health risk as a result of Cd, Pb, As, Mn, Ni, and Cr exposure via herbal tea intake was assessed through estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI). Fungi isolated from the tested herbal tea samples were identified on the basis of colony morphology and microscopic characteristics of reproductive structures. Toxic metals concentration in herbal tea samples for Cd, Pb, As, Mn, Ni and Cr ranged 0.04-0.93, 0.09-2.54, 0.03-0.77, 1.82-651.04, 0.97-9.01, 0.49-3.47 mg/kg of dried plant material, respectively. Values of THQ for investigated toxic metals and HI were below 1, indicating the absence of human health risk. All 14 samples of the tested herbal teas were contaminated with fungi, while total count of cultivable fungi in each sample did not exceed national standards (105 CFU/g). Presence of 23 morphologically different isolates suggested moderate fungal diversity of the samples, while the highest isolation frequency (IF) of 100% was documented for Penicillium spp. and Aspergillus spp. The obtained risk assessment results suggest that all the tested samples are safe for human health regarding the toxic metal and fungal content and provide an important basis for understanding the potential risks of toxic metals and toxigenic fungi intake via commercially available herbal teas.