ADR-0023: Conflicting Chemical Records are never merged; the product in hand governs

Status: Accepted Date: 2026-09-02

Decisions

D-45 The governing SDS is the one for the product the user is holding

Two Chemical Records for the same chemical may both be in the Corpus and may disagree. Neither is merged into the other, and no canonical winner is designated.

D-46 A name search matching several products presents a chooser by product and supplier

Disambiguation is shown, never guessed.

Context

R-39: Doc B's Section 7 forbids storing Acetone with nitrile rubber; Doc C's Section 8 recommends nitrile gloves for prolonged contact. Same chemical, same country, two suppliers, opposite advice on the same material. Under D-18 both are legitimate records.

This is not an edge case for The Plant — a binder holding several suppliers of the same solvent is the normal case.

D-18 already keys records on the document and D-19 identifies by product label, so the mechanism was mostly present; what was missing was the ruling that nothing may be combined.

Rejected options

• Merge conservatively, taking the union of restrictions — sounds safest and is not. It fabricates a document no supplier wrote and nobody is accountable for, and here the union of "wear nitrile" and "nitrile is incompatible" permits no glove at all.
• Curator designates a canonical record per chemical — simpler UI, rejected because it shows a Handler advice from a drum they are not holding, and the substitution is invisible at the point of use.
• Show both records side by side with the conflict highlighted — maximally transparent and genuinely a real safety signal, rejected because it hands an unresolved conflict to someone mid-task who needs one answer. Reconsider for the Safety Officer role if per-role surfaces ever come into scope (D-22 currently excludes them).

This ruling may not be re-decided

If a change contradicts this ADR: stop and raise it. Do not implement over it. Do not deduplicate the Corpus by chemical name.

Coverage

Upstream	Landed in	Evidence	Note
R-39	D-45, D-46	the two-supplier nitrile disagreement is worked in Context