Every metal on the HMTc panel is limited for a reason that can be stated from the government and expert-body record. These pages give that reason, one metal at a time: the toxicological endpoint and the authoritative basis, which foods carry the metal and roughly how much, the people the exposure reaches, and why a certification limit is warranted where a label claim is not. The agency-by-agency assessments are on the analyte panel; the numeric limits are on the standards register; the complete literature is on the Heavy Metal Index.
The panel, metal by metal
8 metals, ordered as the program tiers them: the four zero-tolerance toxics first, then the four that adopt the strictest government limit directly.
Pb
Why we limit lead
Lead is the one contaminant where every major body has declined to name a safe dose — so the whole certification frame is to drive it as low as the supply chain can reach.
Total elemental lead
Cd
Why we limit cadmium
Cadmium is not cleared — it accumulates in the kidney for decades — so the only control is to keep intake low across a lifetime.
Total elemental cadmium
iAs
Why we limit inorganic arsenic
Inorganic arsenic is a carcinogen with no safe intake, and everyday diets — especially rice-based infant foods — already reach the point the cancer assessment is anchored to.
Inorganic arsenic, speciated from total
MeHg
Why we limit methylmercury
Methylmercury crosses the placenta into the developing brain, has no safe threshold, and concentrates in predatory fish — where cooking does nothing to remove it.
Methylmercury, speciated from total
Ni
Why we limit nickel
Nickel is the metal where ordinary diets already run over the tolerable intake — and the most-exposed children run over it further.
Total elemental nickel
Sn
Why we limit tin
Tin is the honest outlier on the panel: its limit guards against an acute stomach upset from failing can linings, not chronic toxicity or cancer.
Total elemental tin (inorganic)
Al
Why we limit aluminium
Aluminium is poorly absorbed but slowly cleared — so ordinary intake can still run up against a low tolerable weekly limit, especially in infants.
Total elemental aluminium
Cr
Why we limit chromium
Chromium is a tale of two forms: the trivalent one is a nutrient, the hexavalent one is a carcinogen — so the whole discipline is telling them apart.
Total chromium; Cr(VI) on trigger