Codex Maximum Residue Limits

An MRL answers a specific question: if this substance is used on this crop in the approved way, what residue is left at harvest? The limit is set at or near the upper end of the residues found in supervised trials reflecting that approved use. It is then verified against health-based reference values to confirm that dietary exposure at the limit remains acceptable. The result is a limit that is simultaneously a good-practice test and a safety-verified one — which is why it does double duty and why it is so easily misread.

Good agricultural practice basis

The limit reflects correct, approved use of the substance — dose, timing, and pre-harvest interval. Residue above it indicates use outside that pattern.

Toxicological verification

The limit is checked against health-based reference values so that exposure at the limit is acceptable. This confirms the limit; it does not define it.

Substance–commodity specificity

A limit exists for a named substance in a named commodity. A limit for one crop says nothing about another, and absence of a limit is not permission.

Residue definition

What is actually measured — parent compound, metabolites, or both — is defined per substance and can differ between authorities for the same substance.

This is the single most consequential fact on the page. Codex MRLs are an international reference; they are not the law anywhere. National and regional authorities set their own MRLs, and those routinely differ from Codex — sometimes because the authority assessed the same data differently, sometimes because a use is not approved in that country at all, sometimes because the authority has not adopted a Codex limit, and sometimes because policy sets a default limit where no specific one exists.

The practical consequence for a trader is blunt: conformity with a Codex MRL does not make a consignment admissible anywhere. The operative test is the importing country’s limit for that substance in that commodity, in force on the day of import, measured against that country’s residue definition and sampling rules. A consignment fully compliant at origin and fully compliant with Codex can still be rejected at destination, and this is the ordinary mechanism of residue rejections rather than an anomaly.

Codex MRLs carry weight in trade law because the WTO SPS Agreement designates Codex as the international standard-setting body for food safety. A member whose residue measures conform to the relevant Codex limit is presumed to be consistent with its SPS obligations; a member setting a stricter limit may be asked to justify it on scientific grounds. This does not oblige any member to adopt a CXL, and many do not.

The result is a system where Codex limits function as a reference point and a negotiating baseline rather than as a harmonised rule. Divergence between Codex and national limits is a recognised, persistent, and largely unresolved friction in agricultural trade — and it is the mechanism behind a large share of border rejections of fresh produce and other treated commodities.

No limit values appear on AgricultureID, for any substance, in any commodity, under Codex or any national authority. This is deliberate and not a gap. A residue limit is meaningful only together with its residue definition, its commodity definition, its sampling and analysis rules, and its date of application — and it changes. A number reproduced without that apparatus, or reproduced accurately and then left to age, is worse than no number, because it invites reliance.

• No Codex MRL values — consult the Commission’s official database of adopted limits
• No national or regional MRL values — consult the importing authority’s own current instrument
• No residue definitions, sampling rules, or analytical methods
• No statement of which uses are approved in any country
• No assessment of whether any consignment complies