On this page
What does "certified compostable" actually test for?
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.
Introduction
Compostability is defined by laboratory standards: what a material must do, under stated conditions, within stated time, to stated completeness. Recyclability is a claim about collection and processing that varies by locality. A certified compostable package is one that has passed a defined battery of tests.
The precision of the specification carries regulatory as well as scientific consequences. The US Federal Trade Commission requires "competent and reliable scientific evidence that all the materials in the item will break down into, or otherwise become part of, usable compost … in an appropriate composting facility, or in a home compost pile or device" before a compostable claim is made (16 CFR § 260.7). The standards examined below are, in practice, the means by which that evidence is generated.
EN 13432: the reference architecture
The European standard EN 13432, harmonised under the Packaging and Packaging Waste Directive, is the reference point against which the other compostability specifications are ordinarily described. Its requirements fall into four families (Vinçotte, n.d.):
Biodegradation — the chemical conversion of the material to carbon dioxide, water and biomass: "at least 90% of the materials have to be broken down by biological action within 6 months", measured under controlled industrial composting conditions.
Disintegration — the physical fragmentation of the article: "after 12 weeks at least 90% of the product should be able to pass through a 2 x 2 mm mesh", that is, no more than 10 per cent residue above two millimetres.
Constituent limits — maximum concentrations of volatile matter, fluorine and a schedule of heavy metals (copper, zinc, nickel, cadmium, lead, mercury, chromium, molybdenum, selenium, arsenic).
Ecotoxicity — demonstration that the resulting compost supports life: germination and biomass tests confirming that plant growth is "not adversely affected" by compost produced with the material.
Two features of this architecture account for much of the confusion that arises downstream. First, biodegradation and disintegration are distinct requirements rather than two descriptions of a single property. A material may fragment completely and yet fail to biodegrade, which is the pattern at issue in the oxo-degradable claims in this section, or may biodegrade chemically while leaving visible residue beyond the applicable time limit. Certification requires that both requirements be satisfied. Second, every threshold is indexed to industrial conditions, comprising sustained elevated temperatures around 58 °C together with managed moisture and aeration, which a domestic compost heap does not reliably achieve. Accordingly, the standard certifies performance within a specified technological environment rather than decomposability in the environment at large.
The regional standards family
The other major standards share EN 13432's four-part architecture while diverging on scope and stringency.
In North America, ASTM D6400 covers plastics designed for aerobic municipal and industrial composting; ASTM D6868 extends the framework to plastic coatings and laminations on compostable substrates; and ASTM D8410 addresses cellulosic-fibre articles. These are the specifications to which the Biodegradable Products Institute certifies, and which US state laws increasingly incorporate by reference. California's compostable-labeling statute requires conformity with D6400 and D6868 as a condition of the claim (BPI, n.d.; CalRecycle, n.d.).
Internationally, ISO 17088 specifies requirements for plastics suitable for recovery through organic recycling and is aligned with the EN and ASTM framework. Its current edition dates from 2021 and entered systematic review in 2026; the standard expressly excludes home composting and open-environment scenarios from its scope (ISO, n.d.). Australia operates a national pair addressing both conditions: AS 4736 for commercial compostability, which adds an earthworm toxicity test not present in EN 13432, and AS 5810 for home compostability, which is among the few specifications at standards level anywhere addressing ambient-temperature performance (ABA, n.d.).
The family's principal internal divergence is chemical. The heavy-metal limits in EN 13432 are substantially stricter than those of the North American specifications: for cadmium, the European limit of 0.5 ppm compares with limits in the 5–17 ppm range under the North American framework, a difference of approximately an order of magnitude that is replicated across several elements (TÜV Austria, 2024). Consequently, a package certified compostable in the United States is not thereby certifiable in Europe. The seals are not interchangeable, and the compost-quality premises underlying them differ.
Home compostability occupies an anomalous position within this architecture and is treated in its own article. In summary, there is no EN-level home-composting standard for packaging generally; the certification scheme OK compost HOME predates the standards that do exist, and those standards — AS 5810 in Australia, NF T51-800 in France, and EN 17427 for carrier bags — were derived from the scheme's criteria, reversing the sequence in which standards ordinarily precede marks (TÜV Austria, n.d.).
The claims-law overlay
Between the standards and the marketplace sits a claims-law overlay whose requirements exceed those of the certificates. The United States formulation states the excess most explicitly.
The Green Guides' compostability section imposes, beyond the scientific-evidence baseline quoted above, a facilities-availability requirement paralleling the recyclability regime: compostable claims require qualification "if such facilities are not available to a substantial majority of consumers or communities where the item is sold" (16 CFR § 260.7). The requirement operates broadly, because industrial composting access in the United States is considerably less extensive than recycling access, and organics programmes accepting compostable packaging, as distinct from yard waste, remain a minority offering. In much of the country, therefore, the unqualified claim "compostable" is unavailable even to a product holding certification.
The section's home-composting and landfill provisions complete the requirement. Qualification is required where the item "cannot be composted safely or in a timely manner in a home compost pile or device", and where consumers would be misled about the benefit when the item is landfilled (16 CFR § 260.7). The latter provision addresses the inference, documented throughout the degradability literature, that a compostable item breaks down harmlessly wherever it is ultimately disposed of. An item certified to EN 13432 or D6400 and disposed to landfill decomposes, if at all, anaerobically, which lies outside every parameter the certificate tested; the Guides render claims trading on the contrary inference actionable.
The overlay is not confined to the United States. The EU claims architecture reaches comparable conduct through the generic-claims prohibitions of the Empowering Consumers Directive, while the packaging regulation's mandatory industrial-only statements and disposal warnings write the qualification directly into the label (Regulation (EU) 2025/40; Complydex, n.d.). Across these regimes the division of function is consistent: compostability certification addresses the material's behaviour under specified conditions, whereas the availability of those conditions in the market of sale is governed separately, and it is on that second question that enforcement has concentrated.
Limits of what certification establishes
The test regime's stringency invites an inference the tests do not support, namely that certified packaging composts in practice. Four gaps separate the certificate from the outcome.
Acceptance. Certification does not address whether composting facilities accept the item. Facility operators exclude certified compostable packaging on contamination-screening, cycle-time or end-market grounds, and the Australasian Bioplastics Association, which administers the AS 4736 verification scheme, states that certification does not guarantee acceptance in any given collection programme (ABA, n.d.).
Operating conditions. The tests are conducted under specified laboratory protocols, whereas operating facilities run shorter, cooler and more variable cycles. A material that achieves 90 per cent biodegradation in six months at 58 °C may leave a ten-week industrial cycle incompletely processed. Such an outcome is not a certification failure but a divergence between the certified scenario and operational practice.
Stream composition. Certification attaches to a product, whereas composting outcomes are determined at the level of the stream: a correctly certified item within a stream contaminated by visually similar non-compostable material shares the fate of that stream. This is the systemic problem that gives compostable labeling, understood as the visual differentiation of certified from uncertified items, a function distinct from compostable chemistry, and it is the function performed by the certification marks examined in the marks article.
Agronomic benefit. Passing the ecotoxicity test establishes the absence of harm to plant growth rather than positive agronomic value. Whether compostable packaging contributes anything to compost beyond bulk remains an open scientific and policy question, and is among the considerations underlying the EU packaging regulation's confinement of mandatory compostable formats to a narrow list of applications — tea bags, coffee pods, ultra-light carrier bags and produce stickers — in which packaging and organic waste are difficult to separate, rather than treating compostability as a general environmental good (Regulation (EU) 2025/40; Complydex, n.d.).
Interaction with law
The standards' legal career may be divided into two phases. In the first, law borrowed them as evidence: the FTC's "competent and reliable scientific evidence" test (16 CFR § 260.7) established conformity with D6400 as the practical substantiation route for US compostable claims without mandating it.
In the second and current phase, law incorporates the standards as elements of legal definitions. California's statute requires D6400 and D6868 conformity, certification by an approved third party, and a total organic fluorine limit restricting PFAS, which is examined in the PFAS article (CalRecycle, n.d.). The EU packaging regulation extends the pattern further, making industrial compostability mandatory for its listed formats by February 2028 while requiring compostable packaging to be labelled as industrially compostable and to warn against disposal in nature (Regulation (EU) 2025/40; Complydex, n.d.). The direction of the development is from compostability as a voluntary claim substantiated by standards toward compostability as a regulated product characteristic whose standards are selected by legislators.
That development alters the governance implications of the standards themselves. While EN 13432 conformity operated as the substantiation of a marketing claim, the standard's content concerned claimants and certifiers. Where statutes now depend upon it, revision decisions taken within CEN and ASTM committees carry regulatory consequence without the procedural apparatus that ordinarily attends regulation. The pattern by which standards acquire legal effect without passing through a legislative process recurs across the articles in this theme.
The internal logic of the four requirement families
Each of the four requirement families addresses a distinct failure mode, and reading them as a designed system accounts for both their sequence and the difficulty of omitting any one of them.
Biodegradation states the claim's central proposition, namely that the material's carbon enters biological circulation, and its threshold of 90 per cent within six months operates to exclude materials that only begin to biodegrade, converting a rate into a requirement of completeness. Disintegration addresses the process rather than the chemistry: a chemically biodegradable article that survives twelve weeks as recognisable fragments contaminates screened compost and prompts the facility rejections described under the acceptance gap above. The 2 x 2 mm mesh criterion accordingly imports the composter's own quality-control criterion into the material's certificate. The constituent limits protect the output of the process, namely compost destined for soil, from accumulating substances that composting does not destroy; the heavy-metal schedule and the fluorine limit thereby anticipate, by several decades, the contamination questions later raised explicitly by PFAS. Ecotoxicity tests the resulting compost's capacity to support plant life as an integrated outcome rather than as an inference drawn from the three preceding families.
The two time limits within the architecture are not co-extensive: disintegration is assessed at twelve weeks whereas biodegradation is assessed at six months. It follows, as a matter of inference from the thresholds rather than as a proposition stated by any source cited here, that the earlier criterion is the one an operating facility running a shorter cycle will encounter first, which is consistent with the description of disintegration as the composter-facing requirement.
Because the architecture is shared across the family, each regional divergence can be located as a policy choice rather than as a technical accident. Australia's added earthworm test extends the ecotoxicity family by one trophic level. The stricter European heavy-metal limits reflect a compost-quality premise that treats agricultural soil as the regime's principal beneficiary. The North American framework's higher metal ceilings sit within the same four-family structure while setting the protective balance differently. Divergence therefore occurs within a shared architecture rather than between incompatible ones, which is the reason mutual recognition of test data between certifiers is feasible even where mutual recognition of certificates is not.
Summary
At the level of the certificate, "certified compostable" is defined by four requirement families, quantified thresholds, accredited testing and an extended history of methodological refinement. The difficulties associated with the claim arise not in the specification of the chemistry but in the chain of inference the seal invites: from laboratory conditions to operating facilities, from product certification to stream outcomes, and from decomposability to benefit. The standards state their own scope, ISO 17088 expressly excluding home composting and open-environment scenarios (ISO, n.d.) and EN 13432 indexing its thresholds to industrial conditions (Vinçotte, n.d.); it is in the marks derived from the standards, and in the marketing built upon the marks, that the stated scope is most often exceeded. The remaining articles in this group follow the same sequence outward: the certification marks that administer the seals, the home-compostable claim, the PFAS limits newly incorporated into certification, and the degradability claims that the compostability framework was constructed to exclude.
References
ABA (Australasian Bioplastics Association) (n.d.) Commercial compostable verification programme. Available at: Open source (Accessed: 18 August 2026).
BPI (Biodegradable Products Institute) (n.d.) Compostability certification. Available at: Open source (Accessed: 18 August 2026).
CalRecycle (n.d.) Truth in labeling for compostable products. Available at: Open source (Accessed: 18 August 2026).
Complydex (n.d.) PPWR labelling requirements: Article 12. Available at: Open source (Accessed: 18 August 2026).
ISO (International Organization for Standardization) (n.d.) ISO 17088:2021 — catalogue record. 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).
TÜV Austria (n.d.) OK compost HOME. Available at: Open source (Accessed: 18 August 2026).
TÜV Austria (2024) Comparison of compostability standards [PD-BA-TABE-CERT-BIO-ID-415]. Available at: Open source (Accessed: 18 August 2026).
Vinçotte (n.d.) Requirements for EN 13432. Available at: Open source (Accessed: 18 August 2026).
16 CFR § 260.7 (Compostable claims). Available at: Open source (Accessed: 18 August 2026).
Note on sources and verification
EN 13432's quantitative requirements are quoted from a certifier's requirements document (Vinçotte, whose scheme is now TÜV Austria's) rather than the standard itself, which was not purchased for this article; the widely circulated summary figures match the certifier document. The heavy-metal comparison (cadmium 0.5 ppm EU versus 5–17 ppm North America) is from TÜV Austria's published standards-comparison table. The PPWR provisions on compostable formats and labeling are drawn from the Regulation's recitals as retrieved from EUR-Lex, supplemented by a secondary compliance analysis for article-level detail; article-level verbatim text could not be retrieved and paragraph citations are therefore avoided. The statement that EN 13432 was harmonised under the packaging directive follows standard technical literature.
Last verified: 18 August 2026.