The instrument
California's Proposition 65 (the Safe Drinking Water and Toxic Enforcement Act of 1986, Cal. Health & Safety Code §25249.5 et seq.) requires the state to publish a list of chemicals known to cause cancer or reproductive toxicity, and requires a warning before a business exposes anyone to a listed chemical above a safe-harbour level. It is a right-to-know labelling statute, not a food-safety standard: a listing establishes a warning obligation, and a safe-harbour level (a No Significant Risk Level for carcinogens, a Maximum Allowable Dose Level for reproductive toxicants) is a warning trigger derived through a fixed formula. Neither is a maximum permitted concentration in food. Five of the HMTc analytes are Proposition 65-listed; for two of them California has adopted no oral safe-harbour at all, so no California number functions as a dietary threshold. This page records the listings and the gap; it does not set any HMTc limit.
The heavy-metal listings
Proposition 65 status for the HMTc analytes California has listed. The oral safe-harbour is the daily dose above which a consumer-product warning is required (µg/day); “none” means California has adopted no oral safe-harbour for that metal. None of these values is a maximum concentration in food. Values transcribed from the OEHHA Proposition 65 list and safe-harbour tables via the Heavy Metal Index regulatory register.
| Analyte | Proposition 65 listing | Oral safe-harbour (µg/day) |
|---|---|---|
| Lead (Pb) | Carcinogen; reproductive & developmental toxicant | MADL 0.5 · cancer NSRL 15 |
| Cadmium (Cd) | Carcinogen; developmental & male-reproductive toxicant (1997) | MADL 4.1 |
| Inorganic arsenic (iAs) | Carcinogen | cancer NSRL adopted; oral value not transcribed here |
| Hexavalent chromium (Cr-VI) | Carcinogen (1987); developmental & reproductive toxicant (2008) | MADL 8.2 (oral) |
| Nickel, soluble compounds (Ni) | Carcinogen (compounds); developmental & male-reproductive toxicant (soluble, 2018) | none (inhalation NSRLs 0.8 / 0.4 only) |
Listed for harm, without a dietary limit
The pattern across the five is the same. California has formally judged each metal to cause cancer or reproductive harm, and for lead, cadmium, and hexavalent chromium it has gone further and set an oral Maximum Allowable Dose Level that operates as a de-facto labelling threshold for consumer products. For inorganic arsenic and nickel it has set no oral safe-harbour at all: the hazard is named on the list, but no California number translates the listing into a dietary pass or fail. And in every case the safe-harbour, where one exists, is a warning trigger measured in micrograms per day of intake, not a maximum concentration in the food itself. Proposition 65 never sets a food maximum level, because that is not what the statute does.
The consequence is a gap. For these metals the operative dietary reference values are the European Food Safety Authority's tolerable intakes and the binding maximum levels are the European Union's; the United States sets no maximum level for any of them in food. California, the one US jurisdiction to have named the hazard in law, stops at a warning and leaves the concentration question unanswered.
How this interacts with HMTc
This gap is the space the certification program occupies. Where a government has named a heavy-metal hazard but set no dietary limit, an HMTc standard adopts the strictest maximum level any credible government has set for that product and analyte worldwide, in the product's native basis, and certifies each lot against it. This page records the sovereign listings and the dietary threshold California did not set; it does not set or justify any HMTc value. The certification limits, and the government maximum levels each one cites, live on the standards, and the full toxicological and occurrence record for each metal is on the analyte pages.