A percentage on a supplier declaration can travel a long way. A manufacturer copies it into a specification, a retailer repeats it on packaging, and customers encounter it as an environmental claim. For sustainable supply chain management, the question is whether the figure still has an identifiable evidential basis at the point of publication. We examine that problem through the standards of scrutiny relevant to our circular economy research. A credible trail should show what material the claim concerns and how the supporting records connect to the product being described.
Start with the claim, not the certificate
Consider the proposed wording ‘contains recycled plastic’. It leaves open basic questions. Does the assertion concern the whole product, one component or only its packaging? Is the material post-consumer or pre-consumer, and does the percentage refer to mass or another measure? The product identifier and reporting period matter too. A dated supplier declaration may cover one batch while marketing proposes wording for the entire range.
A useful claim specification records the material, its stated origin, the relevant product or batch, the claimed proportion and the dates covered. ‘Recyclable’ describes a different property from ‘contains recycled material’; neither statement establishes the other. We would seek these distinctions before deciding whether a broad phrase can be substantiated. For example, evidence limited to a recycled plastic casing cannot justify describing every material in an electronic device as recycled.
Follow the material through each handover
The evidence trail should connect the finished product with the suppliers and materials behind it. Purchase orders, lot references, delivery records and production logs may establish how an incoming material entered a particular manufacturing batch. If blending or substitution occurs, records need to account for it. An upstream supplier's declaration has value, but its scope may be narrower than the customer's final claim.
Independent testing or certification can strengthen confidence when the method, issuing body and covered material are appropriate. It does not automatically verify an entire product range or every environmental benefit attached to that product. The UK Competition and Markets Authority's guidance on environmental claims across supply chains emphasises obtaining credible evidence behind claims passed from one business to another. That is UK consumer-law guidance; organisations elsewhere must check the rules relevant to their market.
Where can the evidence chain break?
A practical review is easier when each document answers a defined question. This illustrative matrix is a research aid rather than a certification procedure. Before using it, identify the specific claim and the product population to which it will apply:
| Evidence requested | What it can verify | Gap to flag |
|---|---|---|
| Batch or lot linkage | Whether material reached the specified product run | No bridge between incoming lot and final item |
| Scope of test or certificate | Which substance, fraction or process received scrutiny | Certificate covers a different component |
| Dated supplier statement | What the supplier asserted at a given time | Document predates a material change |
| Source-change record | Whether substitutions were tracked and reassessed | New upstream source has no supporting evidence |
One missing connection can matter more than a thick folder of unrelated records. Reviewers should ask whether a claim remains supportable after a change of manufacturer, formulation or input stream. The table does not assign a passing score; it points to questions that require documented answers.
Record uncertainty before repeating the claim
If records are incomplete, ask the responsible supplier to substantiate the specific gap. If the response supports only a narrower claim, the wording should match that narrower scope. Where uncertainty remains material, further independent examination may be appropriate; otherwise, the unsupported language should be withheld.
Our approach also draws on the OECD's account of risk-based supply-chain due diligence. It encourages organisations to assess adverse impacts in operations and business relationships, prioritising risks that matter. This broader framework is useful for deciding where to direct verification effort, although it is not a recycled-content certification scheme. Record retention, named responsibility for sign-off and a clear history of revisions make subsequent review possible.
There is a governance question behind the technical detail: who is authorised to repeat a claim when its originator cannot substantiate it? A procurement record, sustainability report and product label may reach different audiences. Each deserves wording that the available evidence can actually carry.
Make the final assertion reviewable
Before a claim leaves the organisation, we would ask whether a person unfamiliar with its supply chain could follow the assertion back to the relevant material records. The answer should remain intelligible after staff or suppliers change. That is the standard of transparency worth pursuing: a claim with identifiable boundaries, documented support and a visible route for correction when new evidence arrives.