Overview
This paper reanalyzes a published open dataset of 34 black teas, each brewed three times in a row from the same leaves, to ask how much discarding the first brew lowers exposure to arsenic, lead and other elements. The authors made no measurements of their own. They report median per-litre concentrations for each infusion and find that discarding the first brew lowers the hazard index by 37.1%, but by only 5.7% when the volume drunk is held equal.
Key numbers
- Total arsenic median: 8.69, 8.5 and 6.38 µg/L in the first, second and third infusion (Table 2, p. 7).
- Lead median: 2.7, 2.66 and 2.4 µg/L; infusion order had no detectable effect on lead (q = 0.418) (Table 2, p. 7).
- Cadmium median printed as 0 in all three infusions, with only 16 of 34 teas positive (Table 2, p. 7).
- Median lead intake 0.0297 µg/kg body weight per day for all three infusions at 10 g tea per day (Section 3.3, p. 8).
Methods (brief)
Source protocol: 1.5 g tea in 40 mL boiled deionized water for 5 minutes, repeated three times on the same leaves, analyzed by ICP-OES. This paper rebuilt the cumulative element mass per tea, then ran paired exposure, hazard-index and arsenic cancer-screening comparisons with bootstrap intervals.
Evidence Fitness
Secondary analysis only: every concentration comes from the Na Nagara et al. 2022 dataset (10.1007/s12011-021-02863-3), which is not in the corpus and would be the better primary source. Detection limits, recoveries and replicate data were not available, so zeros cannot be told from non-detects; no cadmium value is recorded. Infusion values stay in µg/L and are not comparable with leaf concentrations. The normalized “dry-tea equivalent” medians are calculated extractable amounts, not leaf contents. Total arsenic only, no speciation.