Mycotoxins in teas and medicinal plants destined to prepare infusions in Portugal

Consumption of tea and medicinal plant infusions in general has been increasing. The worldwide growing consumption rate of tea and infusions is associated to the health promoting properties and a healthy lifestyle trend, and also to the assumption of minimal or no toxic side effects when consumed in large quantities compared with synthetic drugs. However, tea and the herbs used in the preparation of infusions can be contaminated with mycotoxins, for which no maximum levels are currently established. In this context this study aimed to analyze commercially available teas and medicinal plants destined to be consumed as infusions and assess the resulting exposure to the mycotoxins AFs and ZEA. With such purpose, 37 (convenience) samples of tea and medicinal plants destined to be consumed as infusions were analyzed through a SPE-ELISA analytical set-up. Nearly 84% of the analyzed samples were positive for at least one of the mycotoxins and 43.24% were positive for both AFs and ZEA. None of the samples negative for both AFs and ZEA were tea (i.e. derived from Camellia sinensis). Approximately 65% of the analyzed samples were positive for AF (14.74 ± 7.18 μg/kg). In general, teas featured the highest AFs contamination levels versus medicinal plants. Is it also noteworthy that all analyzed tea samples were AF-positive. Sixty two percent of the samples were contaminated with a ZEA (8.87 ± 5.31 μg/kg). Statistically significantly higher levels of ZEA in organically produced samples were observed. Samples sold in bulk (i.e. not packed) were those with the highest ZEA levels. The highest maximum levels of AFs and ZEA were detected in chamomile flowers (28.15 μg/kg), the second most consumed medicinal plant in Portugal. The degree of exposure of the Portuguese to these mycotoxins through consumption of tea and medicinal plants destined to prepare infusions, was assessed through the Estimated Daily Intake (EDI). For AFs the EDI was 0.13 ng/kg bw/day, which represents 64.12% of the proposed TDI. In the risk assessment, the worst scenario corresponded to conventional produced medicinal plants (122.45%). Conversely, tea and medicinal plants contribute little to the exposure of the Portuguese population to ZEA (EDI = 0.08 ng/kg bw/day). The obtained results proved the need for further studies to evaluate the occurrence of these mycotoxins in these food commodities of increasing consumption, in order to monitor the exposure of the population and, if justified, to serve as the basis for establishing maximum limits for the control of exposure.