Biodegradable meaning: what EN 13432, ASTM D6400 and green-claim laws require

Biodegradable means that microorganisms such as bacteria and fungi can convert a material into water, carbon dioxide and biomass. Under current standards, the word carries weight only when a claim names the environment, the timeframe and the share of the material that has to convert, and for most certifications that share is 90%. Without those three details, the label proves almost nothing.

How does biodegradation work, and why does the environment decide it?

Microorganisms release enzymes that cut polymer chains into pieces small enough to absorb, then use the carbon for energy and release it as CO2. Heat, moisture, oxygen and the local microbial population set the pace.

That dependence led the Washington State Department of Ecology, in a 2014 focus sheet, to call a biodegradability claim meaningless unless the environment and timeframe are specified. A yard waste bag and a mulch film make different promises.

Disintegration is physical: how much of the item still sits on a 2 mm sieve after the test. Biodegradation is chemical, tracked by how much of the material's carbon leaves the test vessel as CO2.

How long does biodegradable material take to break down under each standard?

Most certification schemes set the pass mark at 90% and change the clock. Fresh water is the fastest benchmark at 56 days, industrial compost allows six months, a home compost heap gets 12 months and soil gets two years. Seawater has a six-month certification and a US test method with no pass mark at all.

Biodegradable meaning in industrial and home compost

EN 13432 is the harmonized European standard for packaging recovered through composting, and EN 14995 applies the same tests to plastics in general. ASTM D6400 is its US counterpart, written for municipal and industrial aerobic composting facilities. Both assume a managed site running much hotter than a home compost heap.

Passing EN 13432 doesn't cover a home compost heap. TÜV Austria built OK compost HOME for that case, and the scheme became the basis for NF T51-800 in France. AS 5810 in Australia and EN 17427, a 2022 European standard limited to carrier bags, also set home composting requirements.

Biodegradable meaning in soil and seawater, where the rules thin out

Seawater is the weak spot. According to European Bioplastics, ASTM D6691 sets no pass or fail criteria, and ASTM D7081, the US marine specification, was withdrawn in 2014 with no replacement. A pack that says “tested to ASTM D6691” reports a measurement without a verdict.

ISO 22403:2020 sets test methods and requirements for plastics meant to biodegrade in marine settings, applied to virgin material in lab conditions.

Biodegradable meaning under EU and US labeling rules

From 27 September 2026, EU rules treat a bare “biodegradable” as a banned generic claim unless the same medium spells out what it means. In the US, the FTC Green Guides expect complete breakdown within one year of customary disposal. California bans the word on plastic product labels.

Biodegradable meaning under Directive 2024/825

Directive (EU) 2024/825 adds to the EU blacklist of unfair commercial practices any generic environmental claim the trader can't back with recognized excellent environmental performance. Recital 9 names “biodegradable” and “biobased” as examples, next to “eco-friendly” and “green.” A claim is generic when its specification doesn't appear in clear and prominent terms on the same medium.

Member states had to transpose the directive by 27 March 2026. The separate Green Claims Directive is stuck: the Commission announced its intention to withdraw it on 20 June 2025, and the European Parliament's tracker still listed it as blocked on 1 August 2026.

FTC Green Guides and California

Under 16 CFR 260.8, an unqualified degradable claim for solid waste is deceptive unless the entire item completely decomposes within one year after customary disposal. Items that end up in landfills, incinerators or recycling facilities can't carry that claim, because none of those settings allows complete decomposition within a year.

California's Public Resources Code section 42357, as amended by AB 1201 in 2021, bars selling plastic products labeled “biodegradable,” “degradable” or “decomposable.” “Compostable” is allowed only with ASTM D6400, ASTM D6868 or OK compost HOME, and the product must be an allowable input under the USDA National Organic Program. The law set that requirement for 1 January 2026, but CalRecycle granted a two-year extension for products containing synthetic substances that runs to 30 June 2027.

Biodegradable meaning versus compostable, oxo-degradable and biobased

• Compostable means the item biodegrades and disintegrates in a composting process within set times and leaves no toxic residue. Every certified compostable item is biodegradable under test conditions; plenty of biodegradable materials would fail a compost test.
• Oxo-degradable plastic is a conventional polymer, often PE or PP, with additives that make it fragment through oxidation. Article 5 of Directive (EU) 2019/904 required member states to ban it from 3 July 2021, and ASTM D6954, often cited in its favor, has no pass/fail criteria. Both resins appear among the seven resin identification codes.
• Biobased describes the feedstock (plants or other biomass) and doesn't settle what happens at end of life.

What isn't part of the biodegradable meaning?

A biodegradable label doesn't promise that an item vanishes wherever it lands. An industrial compost certificate covers one managed setting, and landfill, the ocean and home compost are three places the EN 13432 and ASTM D6400 tests never simulate.

A cup certified for industrial composting that goes into a residual waste bin gets none of the benefit. And the logo can't tell you whether a facility near you accepts it.

Which biodegradable claims hold up under current standards?

A claim holds up when it names a certification with a pass mark, the environment and the timeframe. “OK compost HOME” meets that criterion because the scheme fixes 90% in 12 months. “Tested to ASTM D6691” doesn't, and a bare “biodegradable” on a plastic product is already illegal in California; in the EU it joins the blacklist from 27 September 2026 unless the same medium specifies the claim.

For industrial compost, EN 13432 or ASTM D6400 is the certificate to ask for. It is the wrong one for a household with no collection route to a composting facility.

FAQ on biodegradable meaning

What does 100% biodegradable mean?

On a label, “100% biodegradable” comes with no standard to check it against. EN 13432, ASTM D6400 and the TÜV Austria OK schemes set their pass marks at 90%. In OK biodegradable SOIL that 90% can be absolute or relative to a reference material, so a product can pass without the lab recording 90% of its own carbon as CO2.

Is 100% biodegradable the same as compostable?

No. A compost certificate adds tests a biodegradability claim skips: under ASTM D6400-12, as summarized by Washington Ecology, compost made with the product must support germination of two plant species at 90% or more of a control sample, and heavy metals must stay under 50% of the limits in US EPA rule 503.

Does compostable mean no microplastics?

The standards cap fragments above 2 mm. Under EN 13432, no more than 10% of the material may remain in pieces that size after 12 weeks, and nothing smaller is counted at the disintegration stage. The requirement that 90% of the carbon turn into CO2 within six months is the part meant to account for what is left.

Is biodegradable a good thing?

It helps where the item reaches the environment its certificate names, and does little anywhere else. TÜV Austria restricts its marine logo so the label doesn't invite littering: OK biodegradable MARINE applies only to non-floating products with a function at sea, such as fishing line, with a density above 1.05 g/cm³.