Risk assessment of intake of pyrrolizidine alkaloids from herbal teas and medicines following realistic exposure scenarios

In this study five types of herbal teas were used to quantify the effect of comminution of the leaves on resulting PA exposure. Results show that PA levels extracted from intact leaves were consistently lower than from corn minuted tea leaves. The Margin of Exposure (MOE) approach was applied to evaluate the consequences of this difference for the associated risks in the scenario of lifetime exposure. Furthermore, we considered medicinal use of these teas for shorter-than-lifetime exposure scenarios, and also analysed the risks of shorter-than-lifetime use of eight herbal medicines and 19 previously analysed plant food supplements. This analysis revealed that shorter-than-lifetime use resulted in MOE values < 10,000 upon use for 40-3450 weeks during a lifetime, with for only a limited number of herbal teas and medicines use of two weeks a year (150 weeks during a 75 year lifetime) would still raise a concern. It is concluded that taking more realistic conditions into account markedly reduces the concerns raised for these herbal preparations. These results also illustrate the need for development of a generally accepted method for taking short term exposure into account in risk assessment of compounds that are genotoxic and carcinogenic.