Heavy Metals in Tea: Why the Origin of Your Matcha Matters More Than You Think

To understand the heavy metals issue in tea, you first need to understand why matcha is fundamentally different from brewed tea when it comes to contamination.

When you brew loose-leaf sencha or gyokuro, you steep the leaf in hot water and then discard the leaf. Research confirms that when tea is brewed and the leaf discarded, a significant portion of heavy metals present in the leaf remain bound within it and do not extract into the infusion. In one study examining 30 teas, mercury detected in the leaves of 18 samples was entirely absent from the brewed liquid. Lead similarly shows low solubility in hot water relative to its total concentration in the leaf.¹

Matcha is the opposite. Because the entire leaf is stone-ground into a fine powder and then suspended directly in water, you consume everything in the leaf: the antioxidants, the amino acids, the chlorophyll, and any contaminants that are present. This is the same reason matcha delivers more EGCG and more L-theanine per serving than brewed tea. But it also means that if the leaf contains heavy metals, you ingest them in full rather than leaving most of them behind.

This distinction is fundamental to understanding why the origin and quality of matcha deserves far more attention than the origin of, say, a sencha you brew and discard.

Tea plants are natural accumulators of minerals from the soil. If the soil contains elevated levels of lead, cadmium, or arsenic from industrial pollution, agricultural runoff, or historical contamination, those metals are absorbed by the plant and concentrated in the leaves.

China is both the world's largest tea producer and home to some of the world's most industrially affected agricultural land. A landmark study examining 1,225 samples of Chinese tea collected nationally found that 32 percent exceeded China's own national maximum permissible concentration for lead.⁸ A comprehensive 2023 review published in PubMed, summarizing data from 227 published papers, documented measurable contamination of lead, cadmium, arsenic, chromium, and mercury across Chinese teas, with the highest concentrations in southwest China, parts of eastern China, and Shaanxi Province.⁹

The primary causes are documented in the scientific literature: industrial emissions depositing airborne lead particles onto tea plants and surrounding soil, proximity of tea plantations to mining, smelting, and manufacturing operations, and the use of contaminated fertilizers or irrigation water.¹⁰

It is important to note that not all Chinese tea exceeds safe limits, and many responsible Chinese tea producers test and certify their products. The issue is that the contamination risk is geographically and industrially driven, varies significantly by region and producer, and is not visible or detectable by taste, color, or appearance.

For anyone who drinks matcha regularly, particularly as a daily health practice, the following are worth considering:

Origin matters. Japanese matcha from established growing regions such as Uji, Nishio, Yame, and Kagoshima carries a significantly lower contamination risk than unverified Chinese matcha.

Third-party testing matters. Reputable matcha producers provide certificates of analysis from independent laboratories confirming heavy metal levels. This should be available on request or on the producer's website.

Price is a signal. Genuine Japanese matcha made from young spring leaves, properly shade-grown, harvested, and processed, cannot be produced cheaply. If a matcha is priced like a commodity, it almost certainly is not coming from the growing conditions and quality controls that minimize contamination risk.

Whole-leaf consumption demands higher standards. Because you consume every part of the matcha leaf rather than discarding it after steeping, the sourcing standards for matcha should be held to a higher standard than for brewed teas.