Trace a heavy-metal claim back to the document it came from.
Occurrence data, agency limits, and toxicological reference values across the metals, ingredients, and consumer categories the literature covers. Every figure resolves to a source record carrying the study's methods, the extracted values, and the file hash of the document they were read from.
Counts derive from on-disk frontmatter and the structured evidence layer on every build. Source-type counts are normalized across spelling variants.
What this reference is
Heavy metals reach food through routes that have little to do with how a product is made: lead and cadmium deposited in soil from decades of leaded fuel, paint, and industry; arsenic drawn out of groundwater by rice as it floods; mercury concentrated up the marine food chain; nickel and chromium picked up from processing equipment and packaging. Because the routes are environmental, contamination is a property of the commodity and where it was grown before it is a property of any brand.
The Heavy Metal Index reports what the peer-reviewed and regulatory literature says about those routes, one page at a time: what a metal does at what dose, how much turns up in a given ingredient and where that varies, which consumer categories inherit the problem from their inputs, and what each agency has actually set as a limit. Every figure links to the source it came from, which carries the study's methods, the extracted values, and the file hash of the document they were read out of.
It is a reference, not a ranking. It does not test products, name brands, or tell anyone what to buy. Where the evidence is thin or contradictory it says so, and the coverage page states plainly how much of the identified literature has been reviewed so far.
How the Index is kept honest
Three things make a claim on this site checkable: a stated search strategy, a public account of what has and has not been reviewed, and a correction record that does not quietly overwrite the past.
A stated method
The search strategy, inclusion criteria, and extraction rules are published, so a reader can reconstruct how a page arrived at its figures rather than taking them on trust.
Methodology →Coverage in the open
A PRISMA-equivalent flow states how much of the identified literature has been screened, extracted, and synthesized, and which taxonomies remain thin.
Coverage and audits →Corrections on the record
Errata carry the date, the affected value, and the source that resolved it. Page revisions are versioned, and every page is reconstructable from its history.
Errata and revisions →Common questions
Which heavy metals turn up in food?
The ones that recur across the food supply are lead, cadmium, arsenic, and mercury, with nickel, aluminum, chromium, and tin appearing in narrower sets of products. Arsenic and mercury are tracked as species rather than totals, because inorganic arsenic and methylmercury are the forms that drive toxicity and the forms most regulatory limits are written against.
How do heavy metals get into food in the first place?
Mostly through the environment rather than through manufacturing. Lead and cadmium sit in soil from historical fuel, paint, and industrial emissions and are taken up by crops. Arsenic is drawn from groundwater and soil by rice, which floods during growing. Mercury accumulates up the marine food chain, so the largest predatory fish carry the most. Because the pathways are environmental, contamination tends to track the commodity and where it was grown before it tracks any particular producer.
Is there a safe level of lead in food?
No major regulatory body has identified a blood lead level in children below which harm is not observed. EFSA withdrew its tolerable weekly intake for lead in 2010 on the basis that no health-protective value could be derived, JECFA withdrew its own the same year, and the US EPA does not derive an oral reference dose. The operative framing across agencies is to reduce exposure as far as practicable rather than to stay under a single number.
Who sets the limits for heavy metals in food?
Different bodies set different kinds of value, and they are not interchangeable. Codex Alimentarius publishes international maximum levels; the European Commission sets binding maximum levels for the EU; the US FDA issues action levels and guidance rather than binding limits for most foods; EFSA and JECFA derive health-based intake values that inform the others but are not themselves limits; and state programs such as California Proposition 65 set their own thresholds. Each regulation page states the exact value, the matrix it applies to, and the basis it is measured on.
Does the Index test products or rank brands?
No. The Index reports what the published literature and regulatory record say about metals, ingredients, and product categories. It does not test products, does not name brands in its findings, and does not publish brand-by-brand tables. Where third-party testing is cited as a source, the category-level signal is summarized and the reader is pointed at the original for anything brand-specific.
Can I check a claim on any page back to its source?
Yes, and that is the point of the structure. Every figure links to a source record carrying the study citation, its methods, the values extracted from it, and the file hash of the document those values were read out of. Each page also lists its references in citation order, alongside the wider set of sources routed to it, and records its own update history.