Are Disinfection Byproducts (DBPs) Formed in My Cup of Tea? Regulated, Priority, and Unknown DBPs

Globally, tea is the second most consumed nonalcoholic beverage next to drinking water and is an important pathway of disinfection byproduct (DBP) exposure. When boiled tap water is used to brew tea, residual chlorine can produce DBPs by the reaction of chlorine with tea compounds. In this study, 60 regulated and priority DBPs were measured in Twinings green tea, Earl Grey tea, and Lipton tea that was brewed using tap water or simulated tap water (nanopure water with chlorine). In many cases, measured DBP levels in tea were lower than in the tap water itself due to volatilization and sorption onto tea leaves. DBPs formed by the reaction of residual chlorine with tea precursors contributed ∼12% of total DBPs in real tap water brewed tea, with the remaining 88% introduced by the tap water itself. Of that 12%, dichloroacetic acid, trichloroacetic acid, and chloroform were the only contributing DBPs. Total organic halogen in tea nearly doubled relative to tap water, with 96% of the halogenated DBPs unknown. Much of this unknown total organic halogen (TOX) may be high-molecular-weight haloaromatic compounds, formed by the reaction of chlorine with polyphenols present in tea leaves. The identification of 15 haloaromatic DBPs using gas chromatography-high-resolution mass spectrometry indicates that this may be the case. Further studies on the identity and formation of these aromatic DBPs should be conducted since haloaromatic DBPs can have significant toxicity.