Propolis is a complex bee product that is becoming an increasingly important ingredient in the cosmetic industry due to its numerous biological effects. Its chemical composition is highly diverse and depends on the botanical source, geographical origin, and extraction method. In this thesis, we assessed the safety of a German ethanolic extract of propolis as a cosmetic ingredient using the Threshold of Toxicological Concern approach. Based on data from the literature, we analyzed the qualitative and quantitative composition of the extract. Using the Toxtree software, we classified the compounds in the extract into Cramer’s toxicological classes, while ChemOffice was employed to calculate their physicochemical properties, the latter were used to estimate their potential extent of dermal absorption. Assuming a daily application of 18 grams of a cosmetic product containing 0.1 percent propolis extract, we calculated the systemic exposure to individual compounds and compared it with the acceptable arbitrary thresholds for each TTC class and with NOAEL values derived from toxicological studies that consider actual biological effects. We found that most compounds belong to Cramer Class I, indicating no health risk. Although some flavonoids were present in higher concentrations and exceeded the TTC threshold, a more detailed risk assessment could not be performed due to the lack of available NOAEL values. Despite these limitations, the results suggest that, based on known concentrations of individual compounds and their physicochemical properties, the propolis extract does not pose a health risk and is considered safe for use in the intended cosmetic formulation.
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