United States Environmental Protection Agency (US EPA)

United States (federal) · Mixed — IRIS assessments (advisory) + binding water limits · Established 1970 · Authored by Karen Pendergrass, Institute for Contaminant Standards · www.epa.gov

Quick read

The US Environmental Protection Agency contributes two different kinds of value. Its IRIS program derives oral reference doses (RfDs) — health-based daily-intake estimates used in risk assessment, which are advisory. Separately, under the Safe Drinking Water Act, it sets a legally binding maximum contaminant level (MCL) for arsenic in drinking water (10 ppb). EPA’s food-relevant role is largely the IRIS assessments; its binding limits apply to water, not food.

Mandate & scope

The EPA’s heavy-metal role spans assessment and enforcement in different domains. Its Integrated Risk Information System (IRIS) develops oral reference doses and cancer assessments for cadmium, mercury (mercuric chloride and methylmercury), and lead — for which IRIS provides a qualitative carcinogenicity assessment rather than an RfD, reflecting the no-threshold position; the 2025 IRIS inorganic-arsenic review is its most recent. IRIS values are advisory inputs to risk assessment, not food limits. Under the Safe Drinking Water Act, EPA sets a binding MCL of 10 ppb for arsenic in public drinking water — enforceable, but on water rather than food. The Index tracks EPA primarily for its IRIS toxicity values, which underpin US exposure and risk calculations even though they do not govern what may be sold.

Positions across metals

Where it diverges

EPA’s IRIS oral reference doses are intake-based (µg/kg b.w./day) and comparable in basis with EFSA and JECFA intakes, though derived for risk-assessment use rather than as “tolerable” intakes; its drinking-water MCL is a concentration limit on water and is not comparable with food limits. EPA’s methylmercury RfD (0.1 µg/kg b.w./day) is the most conservative of the intake values across bodies, reflecting its derivation from developmental-neurotoxicity data. For lead, EPA’s refusal to set an RfD echoes the EFSA and JECFA no-threshold conclusion.

Lead

Cadmium

Inorganic arsenic

Methylmercury

Inorganic mercury

Update log

Key documents

References

Positions, the update log, and key documents above are generated from the per-instrument regulation pages this body issues, via tools/build-regulator-pages.mjs. The wiki reports what US EPA has published; it does not endorse it. See HMTc separation policy for why reporting regulatory values is kept architecturally separate from certification threshold-setting.