Deposition of Carcinogenic Atmospheric Anthraquinone on Tea Plantation

The detection of the presence of anthraquinone in tea leaves has raised concerns due to a potential health risk associated with anthraquinone. This led the European Union to impose a maximum residue limit of 0.02 mg/kg in dried tea leaves. This study investigates the possible contamination of tea leaves resulting from the deposition of atmospheric anthraquinone using a global chemical transport model that accounts for the emission, atmospheric transport, chemical transformation, and deposition of anthraquinone on the surface, based on the limited existing information on the atmospheric behavior of anthraquinone.  Despite of the large uncertainties in some model parameters, the model shows reasonable agreement with measurements of surface concentrations of anthraquinone. The largest contribution to the global budget of anthraquinone is from residential combustion followed by the secondary formation from oxidation of anthracene, traffic, biomass burning, power generation and industry. The simulations suggest that, in addition to the direct sources of anthraquinone generated during tea manufacturing, the deposition of atmospheric anthraquinone could be a substantial source of the anthraquinone content found on tea leaves in several tea-producing regions, especially near highly industrialized and populated areas of southern and eastern Asia.