Concentrations, Generation and Risk Characterization of Phthalimide in Tea

Abstract

The fungicide folpet is rapidly degrade into phthalimide (PI) during both thermal processing and analytical procedures in sample preparation, thus its residue definition has been modified into the sum of itself and PI. Tea belongs to one of the world’s most popular non-alcoholic beverages, where folpet is not listed as an applicable pesticide. To demonstrate how serious false positives and overestimation in dietary risk caused by the application of new residue definition, the residue pattern of PI in made tea and processed tea leaves, along with its transfer rate during tea brewing and corresponding dietary risk were investigated in present study. The results revealed that PI residue in tea ranged from < 10 μg/kg to 180 μg/kg with the median value of 10 μg/kg, 7.3 % of which were over maximum residue limit established by EU (100 μg/kg, expressed as folpet). PI residue in green tea was obviously higher than that in black, dark and oolong tea. Simulated heating experiments revealed that PI can arise from improper heating of folpet-free fresh tea leaves and thus green tea bears higher risk for its manufacturing employing comparatively higher temperature. The transfer rate of PI during tea brewing was 104 %. Nevertheless, the risk of PI through drinking tea was negligible to human depending on risk quotient (RQ) value, which was lower than 1 significantly.

Keywords: Folpet, Phthalimide, Tea, Manufacturing process, Generation, Risk assessment.