Trace heavy-metal evidence from food to source.

The ones that recur across the food supply are lead, cadmium, arsenic, and mercury, with nickel, aluminium, 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.

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.

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.

It depends on the metal. Rice and rice-derived ingredients dominate inorganic arsenic; large predatory fish dominate methylmercury; cocoa, leafy greens, and some root vegetables carry the most cadmium; spices and some botanicals are recurring lead findings. The Index reports these at the ingredient level, where the contamination originates, and again at the product-category level, where a consumer encounters it.

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 programmes such as California's 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.

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 summarised and the reader is pointed at the original for anything brand-specific.

Yes, and that is the point of the structure. Every figure links to a source record carrying the study's 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.