Identification, formation and control of polar brominated disinfection byproducts during cooking with edible salt, organic matter and simulated tap water

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.

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Aziz

Granger

et al. 2021

“…Initial experiments attempted to characterize the pseudo-first-order conversion rate of oleic acid to 9,10-chlorohydrins. Oleate (1.9 mM; just above the 1 mM critical micelle concentration 37 ) was treated with 30 mM free chlorine at pH 7 in 20 mM phosphate buffer and 8 °C. Conversion to 9,10-chlorohydrins was complete within 15 s, indicating a pseudo-first-order conversion rate > 0.09 s −1 (Figure S4).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Chlorination of free oleic acid vesicles formed both isomers of 9,10-chlorohydrins (i.e., 9-chloro-10-hydroxyoleic acid and 9-hydroxy-10-chlorooleic acid; Scheme ). Recent research identified a series of novel, brominated or iodinated byproducts that formed when rice or wheat flours were heated in chlorinated or chloraminated tap waters to simulate cooking waters; byproducts included soluble free (i.e., not lipid-bound) brominated fatty acids. , However, the halogenated free fatty acids were not quantified and the analysis did not include lipid-bound fatty acid byproducts.…”

Section: Introductionmentioning

confidence: 99%

Formation of Oleic Acid Chlorohydrins in Vegetables during Postharvest Chlorine Disinfection

Simpson

Suh

Plewa

et al. 2021

High chlorine doses (50–200 mg/L) are used in postharvest washing facilities to control foodborne pathogen outbreaks. However, chlorine can react with biopolymers (e.g., lipids) within the produce to form chlorinated byproducts that remain in the food. During chlorination of micelles of oleic acid, an 18-carbon alkene fatty acid, chlorine added rapidly across the double bond to form the two 9,10-chlorohydrin isomers at a 100% yield. The molar conversion of lipid-bound oleic acid to 9,10-chlorohydrins in chlorine-treated glyceryl trioleate and produce was much lower, reflecting the restricted access of chlorine to lipids. Yields from spinach treated with 100 mg/L chlorine at 7.5 °C for 2 min increased from 0.05% (0.9 nmol/g-spinach) for whole leaf spinach to 0.11% (2 nmol/g) when shredding increased chlorine access. Increasing temperature (21 °C) and chlorine contact time (15 min) increased yields from shredded spinach to 0.83% (22 nmol/g) at 100 mg/L chlorine and to 1.8% (53 nmol/g) for 200 mg/L chlorine. Oleic acid 9,10-chlorohydrin concentrations were 2.4–2.7 nmol/g for chlorine-treated (100 mg/L chlorine at 7.5 °C for 2 min) broccoli, carrots, and butterhead lettuce, but 0.5–1 nmol/g for cabbage, kale, and red leaf lettuce. Protein-bound chlorotyrosine formation was higher in the same vegetables (5–32 nmol/g). The Chinese hamster ovary cell chronic cytotoxicity LC50 value for oleic acid 9,10-chlorohydrins was 0.106 mM. The cytotoxicity associated with the chlorohydrins and chlorotyrosines in low masses (9–52 g) of chlorine-washed vegetables would be comparable to that associated with trihalomethanes and haloacetic acids at levels of regulatory concern in drinking water.

“…Hep G2 cell cytotoxicity assay was used to evaluate the comparative cytotoxicity of eight new identified and two regulated DBPs. The methodology follows previous studies. , The Hep G2 cells were rinsed with PBS, trypsinized, and then transferred into 96-well plates with the cell density of about 2 × 10 4 cells/well. The cells in 96-well plates were incubated in DMEM at 37 °C with 5% CO 2 for 24 h. After 24 h growth, the cells in each well were exposed to different DBPs with different concentrations for another 24 h. Stock solutions at 200 times the working concentration were prepared in dimethyl sulfoxide (DMSO), with 0.5 μL of each stock solution added into each 100 μL well, with 0.5 μL of DMSO added as a negative control.…”

Section: Methodsmentioning

confidence: 99%

Identification, Occurrence, and Cytotoxicity of Haloanilines: A New Class of Aromatic Nitrogenous Disinfection Byproducts in Chloraminated and Chlorinated Drinking Water

Zhang

Bond

Pan

et al. 2022

Self Cite

Identifying disinfection byproducts (DBPs) with high health risk is an unresolved challenge. In this study, six members of a new class of aromatic nitrogenous DBPs2-chloroaniline, 2-bromoaniline, 2,4-dichloroaniline, 2-chloro-4-bromoaniline, 4-chloro-3-nitroaniline, and 2-chloro-4-nitroanilineare reported as DBPs in drinking water for the first time. Haloanilines completely degraded within 1 h in the presence of chlorine (1 mg/L), while about 20% remained in the presence of chloramine (1 mg/L) after 120 h. Haloanilines showed high stability in the absence of disinfectants, with <30% degradation at pH 5–9 over 120 h. Eight haloanilines were determined in chloraminated finished water and tap water at total concentrations of up to 443 ng/L. The most abundant was 2-bromoaniline, with a median concentration of 104 ng/L. The cytotoxicity of eight haloanilines and regulated trichloromethane and dichloroacetic acid (DCAA) was evaluated using Hep G2 cell assay. The EC50 values of eight haloanilines were 1–2 orders of magnitude lower than those of the regulated DBPs. The lowest toxic concentration of 2-chloro-4-nitroaniline was 1 μM, 500 times lower than that of DCAA. The formation and control of haloanilines in drinking water warrant further investigation.