On this page
Mass balance: can a pack containing no recycled molecules carry a "30% recycled" claim?
Marks and reference graphics are shown for identification, academic research and commentary. The image does not grant permission to apply a scheme mark to packaging; consult the issuing body's current eligibility and artwork rules.
The accounting question behind the label
Chemical recycling separated the recycled-content claim from the package’s physical composition. When mixed plastic waste is cracked to pyrolysis oil and fed into a plant alongside fossil naphtha, the output polymers are molecularly indistinguishable. No analysis of the finished package can establish what share of its carbon originated in waste. Mass-balance accounting fills that gap. It is also the controversy.
The question posed in this article's title has not been settled: certifiers answer it one way, NGO critics another, and regulators have not answered it definitively for most markets.
The machinery
Mass balance is a chain-of-custody model, consisting of bookkeeping rules that connect certified input entering a system to certified claims leaving it. Its governing constraint is conservation: a site cannot attribute more recycled character to outputs than the recycled inputs it received, audited period by period. Its governing permission is detachment, in that recycled character may be assigned to outputs within the balance in proportions that do not track physical incorporation. One tonne of certified pyrolysis oil entering a cracker alongside ninety-nine tonnes of naphtha yields, physically, a uniform 1 per cent throughout the output; under mass balance, however, the site may instead attribute the full tonne's worth of recycled character to a chosen 1 per cent of output, sold as "100% recycled (mass balance)", while the remainder carries none.
The leading scheme for such claims, ISCC PLUS, formalises the permission in three attribution options of graduated stringency (ISCC, n.d.). Free attribution allows recycled character to be assigned to any output within the certified system's guardrails, and is the option affording the widest marketing flexibility. Fuel-use-excluded attribution bars the assignment of recycled character to outputs destined for fuel, addressing the artefact of free attribution to which critics have most objected, in which recycled content is claimed on durable products while the physically corresponding material is burned. Proportional attribution requires claims to track each output's actual share, and is the option under which the accounting and the physical composition converge. An "ISCC PLUS certified" statement does not itself disclose which option was applied; that information is recorded in the certificate.
Other schemes take positions along the same spectrum. SCS's recycled-content standard accepts mass balance but requires the chain-of-custody model to be disclosed in all claims, including on-product logos, addressing the question through transparency (SCS Standards, n.d.). The physical-segregation schemes examined in the certification article sit at the spectrum's molecular end.
The case advanced for mass balance
The argument advanced in support of mass balance is infrastructural. Chemical recycling's outputs enter shared industrial systems, comprising crackers, polymerisation trains and resin pools, which cannot be segregated without duplicating the petrochemical industry. On this argument, if recycled feedstock must be physically traceable to the final package, then chemically recycled content can never be claimed at the scale at which those systems operate, investment in waste-to-feedstock capacity loses its market signal, and the recycled-content mandates now multiplying across jurisdictions become unmeetable for precisely the hardest streams, namely films, flexibles and contaminated plastics, that chemical routes address. Mass balance is accordingly presented by its proponents not as a marketing convenience but as the enabling condition for capital formation in advanced recycling, the claim travelling ahead of the molecule so that the molecule's infrastructure can be financed. The model's defenders point additionally to its established use in certified commodities such as renewable electricity, sustainable palm oil and certified cocoa, where attribution accounting is the accepted condition of using shared infrastructure.
The critique advanced by ECOS, Zero Waste Europe and the Rethink Plastic Alliance
The critics' argument concerns the claim rather than the chemistry. The joint position paper by ECOS, Zero Waste Europe and the Rethink Plastic Alliance objects that free-attribution mass balance "could allow for the liberal allocation of recycled feedstock to the final product of their choosing, regardless of its true content", such that a product could be marketed as "fully recycled" while containing "only very small fractions of actual recycled content"; in the words of ECOS's Mathilde Crépy, "with the 'mass balance approach', we open the door to the creative accounting of recycled plastic content" (Zero Waste Europe, 2021; ECOS et al., 2021). The paper's recommendations would prohibit credit-trading between disconnected sites and confine claims to physically meaningful allocation.
Three distinct objections may be distinguished within that critique. The first concerns consumer deception: on this objection, a shopper reading "30% recycled" understands a physical assertion, and attribution claims trade on that understanding. It is an objection about labeling, and is answerable in principle by disclosure of the model, as SCS requires. The second concerns system inflation: free attribution, combined with failures to exclude fuel uses, can attribute recycled character to durable goods while the corresponding physical material is combusted, thereby overstating the system's circularity. It is an objection about accounting design, and is answerable by stricter attribution options. The third concerns mandate integrity: if statutory recycled-content minimums can be met with attributed rather than physical content, the mandates' function of drawing actual recyclate into actual packaging is diluted. That objection concerns regulatory purpose, and only rule-makers can answer it.
The regulatory state of play
Rule-makers are answering unevenly. The EU's packaging regulation sets recycled-content minimums counting only post-consumer material, with the methodology for calculating and verifying those percentages, including the treatment of chemical recycling and attribution, delegated to implementing acts whose content has been closely contested within the sector (Regulation (EU) 2025/40). The direction of pressure is indicated by the existence of the fuel-use-excluded option, attribution models converging toward rules that at least prevent recycled character from being claimed on products while corresponding volumes are burned. In the United States no federal resolution exists; California's beverage-container mandate operates on post-consumer content substantiated to the regulator, and the FTC's Green Guides require content claims to be substantiated for the product as sold, a standard whose application to attributed content the Commission has not definitively addressed. Mass balance is accordingly legal by default in most markets, disclosed by exception where schemes such as SCS require disclosure, and definitively regulated almost nowhere.
Attribution and the statutory minimums
The controversy's consequences concentrate where attribution accounting meets the statutory minimums examined in the mandates article, and the structure of that interaction can be stated even though its resolution cannot.
Both mandate regimes count post-consumer material only, California's beverage-container minimums and the EU's Article 7 alike, importing the ISO-derived material-history definitions into compliance arithmetic. Attribution does not manufacture material history: certified mass-balance systems track the recycled input's provenance, and a pyrolysis-oil stream from post-consumer film remains post-consumer in the ledger. The interaction is therefore not definitional but locational, in that attribution decouples the place at which recycled character is claimed from the path along which recycled molecules travel, whereas the mandates attach to specific products, as with the EU's per-unit category minimums, or to portfolios, as with California's average. Free attribution under a mandate would consequently permit concentration strategies, in which recycled character is steered toward the regulated categories and fossil physics elsewhere, satisfying the letter of compliance while leaving the mandated categories' physical composition unchanged.
Whether such strategies satisfy the mandates is the question the pending EU methodology must decide, and the available decisions are visible in the attribution options themselves: a fuel-exclusion rule prevents the largest leakage; category-fencing rules, permitting attribution only within the regulated category or only within food-contact-equivalent processes, would narrow concentration further; and proportional allocation would eliminate it. Each tightening trades chemical-recycling investment signal against mandate integrity, which is the same trade that the NGO critique and the industry case have contested at the level of principle and that now falls to be settled as calculation rules (ECOS et al., 2021; ISCC, n.d.).
California's regime, portfolio-averaged and reported to the regulator, poses the question in a weaker form: averaging already permits concentration across a producer's fleet, so attribution adds less that is novel. The state's verification of claimed content nevertheless confronts the same evidentiary question of what documentation demonstrates post-consumer character through a shared cracker. The mandates therefore inherit the controversy at the point at which they are operationalised, each recycled-content statute constituting, whether or not its drafters intended it, an implicit position on mass balance pending its implementing rules.
The pedigree argument examined
The defenders' appeal to mass balance's established service in renewable electricity, palm oil and cocoa admits of examination on its own terms, because the analogy contains a disanalogy that accounts for much of the packaging controversy.
In the pedigree cases, the attribute being attributed is invisible at every point in the chain and irrelevant to the product's function. Electrons from a wind farm and from a coal plant are identical at the socket; certified and conventional cocoa make the same chocolate. The attribute purchased is upstream conduct, and the parties transacting understand the certificate as a claim about the system rather than about the kilowatt-hour. The consumer proposition is explicitly systemic: payment finances renewable generation somewhere, or sustainable farming somewhere. Attribution accounting fits those cases because the claim was never presented as a claim about the physical item.
Recycled content arrived with the opposite semantics. For decades the claim was physical, referring to mechanically recycled resin that was visibly present and sometimes greyer or cloudier in consequence, and consumers, regulators and the ISO definitions alike constructed their understanding on molecular presence. Mass balance imports systemic accounting into a claim family whose words continue to carry their physical meaning. The pedigree cases did not carry that inheritance, no comparable prior expectation of physical correspondence having attached to them. The packaging dispute is therefore not about whether attribution accounting is legitimate in itself, the commodity systems having settled that, but about whether a claim vocabulary built for physical composition can be re-founded on ledgers without notice to those reading it. In the renewable-electricity case the resolution was linguistic differentiation: "100% renewable electricity" is understood as a supply-contract claim rather than a claim about the socket, because the market established that understanding from the outset. The packaging equivalent, a disclosed and distinct attribution claim, corresponds to the SCS route. Followed to that conclusion, the pedigree argument supports the critics' disclosure remedy rather than the undisclosed status quo.
What a mass-balance claim does and does not assert
A certified mass-balance recycled-content claim asserts that, within an audited system over an accounting period, recycled inputs corresponding to the claimed quantity entered the system, were not double-counted, and were attributed to this product line under the scheme's rules. That assertion carries the disciplines of conservation, audit and revocation, which distinguish certified attribution from unverified assertion.
It does not assert that the package contains the stated share of recycled molecules; under free attribution it is compatible with the package containing none. It does not disclose, absent scheme rules requiring disclosure, which attribution option was used, that being the variable on which the claim's physical meaning depends. It does not assert that the attributed feedstock displaced virgin production one for one, which is a lifecycle question attribution accounting does not reach. Nor does it answer the question posed in this article's title, that question being normative: whether accounting presence should license the words "30% recycled" on a consumer package is what certifiers, critics and regulators are contesting.
Summary
Mass balance may be characterised as a solution developed for one problem and currently being tested as the answer to a different one. As infrastructure accounting, that is, as the means by which shared industrial systems can host certified flows, it is orthodox and disciplined, and no critic among those cited proposes segregated crackers. As consumer communication, it extends the recycled-content claim beyond the physical sense in which the words on the pack were established, attribution repurposing them for ledger presence without a corresponding change of terminology. The stable resolutions available are correspondingly divided. Either the claim's language differentiates, with "recycled (mass balance attributed)" treated as a distinct and disclosed claim type, generalising the SCS route, or the accounting tightens until attribution approximates physical composition, which the proportional option would require. The present position is neither: identical labels carry different physical compositions, with the difference recorded only in certificates that consumers do not see. What consumers understand such claims to assert is examined in the evidence theme; on the research available to date, they are not informed that the question arises.
References
ECOS, Zero Waste Europe and Rethink Plastic Alliance (2021) Determining recycled content with the 'mass balance approach' — joint position paper, 10 February. Available at: Open source (Accessed: 18 August 2026).
ISCC (n.d.) Mass balance and attribution: understanding the difference. Available at: Open source (Accessed: 18 August 2026).
Regulation (EU) 2025/40 of the European Parliament and of the Council of 19 December 2024 on packaging and packaging waste, OJ L, 2025/40, 22.1.2025. Available at: Open source (Accessed: 18 August 2026).
SCS Standards (n.d.) Recycled Content Standard (SCS-103). Available at: Open source (Accessed: 18 August 2026).
Zero Waste Europe (2021) Press release: Zero Waste Europe and ECOS to the European Commission — mass balance approach blocks ambitions for increased recycled content in plastics, 18 February. Available at: Open source (Accessed: 18 August 2026).
Note on sources and verification
The three ISCC attribution options and their definitions are from ISCC's own explanatory material as cited. NGO critique quotations are verbatim from the Zero Waste Europe press release accompanying the joint paper; the paper itself is linked via the ECOS announcement page. The sources use "free/liberal allocation" as their term; this article uses "free attribution" for consistency with ISCC's vocabulary, and the two usages refer to the same practice. The characterisation of EU implementing-act debates over calculation methodology reflects the state of sector reporting; no specific draft act is cited because none had been adopted at verification date. The description of pyrolysis-based chemical recycling is technical background. The statement that mass balance is definitively regulated almost nowhere is a summary across the jurisdictions covered in this collection, current to the verification date.
Last verified: 18 August 2026.