Key Takeaways & Executive Findings
- •• • Perchlorate was detected in 100% of 132 tea samples from Anhui, with concentrations ranging from 0.011 to 1.611 mg·kg−1; 2.3% exceeded regulatory limits, indicating widespread contamination and potential hotspots. • • Chlorate detection rate was only 15.9%, with maximum concentration 0.040 mg·kg−1 and zero exceedances, suggesting minimal chlorate contamination in Anhui teas. • • Perchlorate levels varied significantly by tea type and origin; yellow tea had the highest mean concentration, followed by green, black, and white tea, with central Anhui (Lu'an City) showing the highest levels. • • Health risk assessment showed all hazard quotients (HQs) for perchlorate were below 1, even at P95 exposure levels, indicating acceptable risks for all consumer groups; chlorate HQ was 0.003, far below 1.
Abstract
This study investigated the pollution characteristics of chlorate and perchlorate in tea from Anhui region and assessed the health risks associated with tea consumption. A total of 132 tea samples, including green tea (n=89), black tea (n=30), yellow tea (n=10), and white tea (n=3), were collected from major tea-producing areas. Chlorate and perchlorate levels were quantified using isotope dilution liquid chromatography-tandem mass spectrometry. Chlorate was detected in 15.9% of samples, with concentrations ranging from not detected to 0.040 mg·kg−1, and no samples exceeded the regulatory limit. Perchlorate was detected in 100% of samples, with concentrations ranging from 0.011 to 1.611 mg·kg−1, and 2.3% of samples exceeded the limit. Pollution characteristics analysis revealed that perchlorate levels were significantly correlated with tea type and geographical origin, with environmental contamination in tea-growing areas being the primary determinant. A significant positive correlation was also observed between chlorate and perchlorate levels. Health risk assessments were conducted for the general tea-consuming population, sub-groups loyal to specific tea types (green and black tea), and sub-groups preferring local tea from high-pollution regions (Lu'an City and central Anhui). Assessments were based on mean and 95th percentile (P95) exposure levels. For chlorate, the maximum hazard quotient (HQ) was 0.003, far below 1, indicating negligible risk. For perchlorate, all HQ values were below 1, regardless of tea type or region, based on both mean and P95 levels, using the Chinese provisional tolerable daily intake (tTDI). However, perchlorate contamination in central Anhui, particularly Lu'an City, warrants continued monitoring due to elevated levels and occasional exceedances.
1. Introduction
Chlorate and perchlorate are emerging contaminants that can disrupt thyroid function by inhibiting iodide uptake. Tea, a widely consumed beverage, can accumulate these anions from contaminated soil and water, posing potential health risks to habitual drinkers. Previous studies have reported perchlorate contamination in tea from various regions, but comprehensive risk assessments for Chinese tea-producing areas remain limited. The lack of region-specific data hinders the establishment of targeted safety guidelines and monitoring programs.
This study addresses this gap by systematically analyzing 132 tea samples from Anhui, a major tea-producing province, using validated isotope dilution LC-MS/MS. The research provides baseline contamination data and conducts multi-dimensional health risk assessments for different consumer sub-groups, including those loyal to specific tea types and local products. By linking contamination levels to geographical origins and tea types, the study identifies high-risk areas and informs targeted regulatory actions to safeguard public health.
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WANG Xiuli, XIE Ji'an, YU Xuerong, ZHAO Ziwei, ZHUANG Meihui, DING Gang, LIU Bolin (2026). Pollution Characteristics and Risk Assessment of Chlorate and Perchlorate in Tea from Anhui Region, China. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2025032601
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Frequently Asked Questions
What is the detection limit and quantification method for chlorate and perchlorate in tea samples?
The study employed isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) with isotope internal standards for quantification. The method achieved detection limits sufficient to quantify chlorate down to non-detect levels (with a maximum of 0.040 mg·kg−1) and perchlorate from 0.011 mg·kg−1 upwards. The method is validated for accuracy and precision, ensuring reliable data for risk assessment.
How do perchlorate levels in Anhui teas compare to regulatory limits and international guidelines?
Perchlorate levels ranged from 0.011 to 1.611 mg·kg−1, with 2.3% of samples exceeding the Chinese regulatory limit (likely 0.5 mg·kg−1 for tea). The mean levels are comparable to or lower than those reported in other Chinese regions, but the presence of exceedances in Lu'an City indicates a need for targeted monitoring. The risk assessment used the Chinese provisional tolerable daily intake (tTDI) to derive health-based guidance values, and all HQ values were below 1, suggesting no immediate health concern for average consumers.
What are the implications of the significant correlation between chlorate and perchlorate levels in tea?
The significant positive correlation suggests common sources of contamination, likely from agricultural practices (e.g., use of chlorinated fertilizers or water) or environmental pollution. This implies that mitigation strategies targeting one contaminant may also reduce the other. It also supports the need for integrated monitoring of both anions in tea production areas.
How does tea type and geographical origin influence perchlorate contamination, and what are the practical implications for consumers?
Perchlorate levels varied significantly by tea type and origin. Yellow tea had the highest mean concentration, while white tea had the lowest. Geographically, central Anhui (especially Lu'an City) showed higher contamination, likely due to local environmental pollution. For consumers, this means that choosing teas from less contaminated regions or types may reduce exposure. For regulators, it highlights the need for region-specific safety standards and targeted interventions in high-risk areas.
What are the limitations of this study and what future research is recommended?
The study is limited by its cross-sectional design and sample size (132 samples), which may not capture seasonal variations. Future research should include longitudinal monitoring to assess temporal trends, expand sampling to other tea-producing regions, and conduct biomonitoring studies to validate exposure estimates. Additionally, investigating the sources of contamination in high-risk areas (e.g., soil, water, fertilizers) is crucial for developing effective mitigation strategies.
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