Fan et al. 2025 — Heavy metals in green tea from Hangzhou area (n=120, ICP-MS)
This study is the most analytically comprehensive recent survey of heavy metals in Hangzhou-area green tea, measuring 15 elements (Al, As, Ba, Cd, Cr, Cu, Hg, Li, Mn, Ni, Pb, Sb, Se, Sn, V) in 120 tea samples by ICP-MS. All 120 samples were below Chinese standard limit values for As, Cd, Cr, Hg, and Pb (NY659-2003; GB2762-2022). The comprehensive pollution index (P = 0.094) and all single-factor pollution indices were well below 0.7, placing Hangzhou-origin tea in the “safe/clean” classification. Health risk assessment yielded a cumulative hazard index (HI) of 0.42, with Mn the dominant contributor (HQ = 0.40); the study concludes that green tea consumption from this region poses no meaningful health risk.
Key numbers
All concentrations in tea leaves (mg/kg dry weight, Table 4):
- Al: range 126.00–975.00, mean 276.50 ± 148.50, median 227.00
- As: range 0.013–0.17, mean 0.054 ± 0.030, median 0.047
- Cd: range 0.0093–0.17, mean 0.040 ± 0.024, median 0.034
- Cr: range 0.044–3.52, mean 0.62 ± 0.55, median 0.42
- Cu: range 7.48–31.00, mean 13.80 ± 3.68, median 13.25
- Hg: range ND–0.017, mean 0.0033 ± 0.0034, median 0.0028 (detection rate 69.2%)
- Mn: range 202.00–2010.00, mean 836.00 ± 274.76, median 814.50
- Ni: range 2.03–29.90, mean 10.70 ± 4.37, median 10.35
- Pb: range 0.051–1.71, mean 0.45 ± 0.30, median 0.37
- Sb: range ND–0.22, mean 0.022 ± 0.022, detection rate 98.3%
- Se: range ND–0.18, mean 0.076 ± 0.040, detection rate 93.3%
- Sn: range ND–12.80, mean 0.18 ± 1.22, detection rate 94.2%
Chinese standard limits for tea (Table 2): As 2.0, Cd 1.0, Cr 5.0, Hg 0.3, Pb 5.0 mg/kg
Health risk (Table 7): HQ values — Mn 0.40, Ni 0.0061, Pb 0.0014, Cd 0.00025, As 0.0020, Hg 0.00012, Al 0.0031; total HI = 0.42
Methods (brief)
ICP-MS (Agilent 8900). Microwave digestion with 5mL HNO₃. Internal standard: indium (In) 3µg/L. Samples collected from supermarkets (67), local markets (43), and planting sites (10) across six Hangzhou districts (Xihu, Fuyang, Linan, Chunan, Jiande, Tonglu/Jiande). LODs 0.0003–0.03 mg/kg. Standard reference material GBW10052 (GSS-30); recoveries 86.4–97.5%.
Limitations
Geographic scope limited to Hangzhou area — cannot be generalised to all Chinese green tea. Market samples dominate (supermarket + local market = 110 of 120); origin labelling reliability not assessed. Total Cr reported; Cr-VI not speciated. Mn contributes 95% of the HI but Mn is generally not considered a regulatory concern in tea at these concentrations. No leaching/infusion data — all dry-leaf concentrations.
Implications
- Certification: Hangzhou-origin green tea is clean by Chinese standards and by health risk metrics. Pb mean 0.45 mg/kg (dry leaf) and Cd mean 0.040 mg/kg (dry leaf) are well within limits. Al at mean 276 mg/kg (dry leaf) is the highest non-Mn metal by mass and is relevant for HMT&C Al-containing products assessment.
- Courses: Good illustrative study for “clean origin” baseline — Hangzhou (Longjing/Dragonwell tea region) as a low-risk Chinese origin.
- App: Dry-leaf Pb 0.45 mg/kg and Cd 0.040 mg/kg for Hangzhou green tea. Convert to as-consumed basis using typical leaching fraction (~30–45% for Pb, ~10–44% for Cd per Brzezicha-Cirocka 2016). Flag for synthesis pass on tea.