Overview
This Thai-language study with an English abstract measured lead, arsenic, cadmium, aluminum and mercury by ICP-MS in 12 top-selling pure matcha powders sold in Thailand, and estimated exposure at 5 g of matcha per day. The authors report all five elements in every product. Both authors are at Dhurakij Pundit University.
Key numbers
- Lead: 184.05 to 1,041.54 ug/kg across products; mean 403.53 ± 266.64 ug/kg (n = 12) (Table 2).
- The single Thai-produced culinary-grade product had the highest lead, 1,041.54 ± 56.24 ug/kg (Table 2, product 07).
- Cadmium mean 30.60 ± 25.01 ug/kg; arsenic mean 43.10 ± 49.16 ug/kg; mercury mean 11.65 ± 4.93 ug/kg (Table 2).
- Aluminum mean 618,921.8 ± 159,760.4 ug/kg (Table 2).
Methods (brief)
About 1 g of powder was microwave-digested with nitric acid and hydrogen peroxide and analysed by ICP-MS at a Chulalongkorn University instrument center. Each product was analysed three times. No detection limits, reference materials or recoveries are reported.
Evidence Fitness
Direct evidence for matcha powder, with per-product values on an as-sold basis. Limits: 12 products, no stated QA or LOD, no purchase dates, and a Thai journal without a DOI whose peer review is unverified, so it does not replace DOI-registered matcha studies. The authors call a lead margin of exposure of 18 low concern; that judgment is theirs. Arsenic is total arsenic.