Biodegradation Additives for Plastics: 5 Types (Oxo, Enzymatic and Pro-Degradant), Evidence and Rules

Biodegradation additives are substances compounded into a plastic so that the finished article fragments or breaks down faster after disposal, and 5 types are sold for that purpose: pro-oxidant (oxo) masterbatches, biotransformation additives, organic biodegradation promoters, enzymatic additives and photodegradable additives. Products made from oxo-degradable plastic have been prohibited across the EU since 3 July 2021, while an engineered enzyme dosed at 0.02 % w/w disintegrated a PLA film under home-compost conditions within 20 to 24 weeks, so which of the 5 routes survives a technical check?

The 5 classes divide by chemistry and host polymer: pro-oxidant masterbatches carry iron, manganese or cobalt carboxylates (PE, PP), biotransformation additives aim at the molecular-weight endpoint of PAS 9017:2020 (polyolefins), organic biodegradation promoters are non-metal blends sold on a micro-organism attraction claim (PE, PET), enzymatic additives are hydrolases dispersed in the melt (PLA, PCL), and photodegradable additives use ultraviolet light as the trigger (films in the field). Only the fourth acts on the backbone by hydrolysis; the first three act by oxidation, which cuts chains without converting carbon to CO2, water and biomass.

This page separates the 4 terms the trade uses as synonyms, sets out the 5 classes, explains the two-stage pro-oxidant mechanism, states each dosage with its source labelled, reports 6 landmark studies, lists the test standards and what each does not prove, maps the EU prohibition and the US claim rules, answers the food-contact question for the three metals and gives a 5-step route selection. The substance records behind the tables sit in our plastic additives database.

Table T1. The 5 classes of biodegradation additive at a glance.

What Are Biodegradation Additives?#

A biodegradation additive is a substance added to a conventional plastic to accelerate its breakdown after disposal, and EU law defines the best-known sub-class, oxo-degradable plastic, as plastic materials that include additives which, through oxidation, lead to the fragmentation of the plastic material into micro-fragments or to chemical decomposition (Directive (EU) 2019/904, Article 3(3)). That definition puts fragmentation and chemical decomposition on the same line as alternatives, so an additive that satisfies only its first half still meets the legal description of oxo-degradable plastic without converting any carbon into CO2, water and biomass. The literature calls the same materials PAC plastics, pro-oxidant additive containing plastics.

Which products are therefore not in this family? Compostable polymers such as PLA, PBAT and PHA are polymers, not additives, which is why they appear here only as the comparison route. Bio-based content is a second exclusion: biodegradability depends on the chemical structure of the polymer, not on the origin of its carbon. Biodegradation additives are one of the 43 families of plastic additives covered on this site, and the only family whose central question is whether the marketed effect exists at all.

Degradable, biodegradable, compostable and oxo-degradable: 4 words that are not synonyms#

Degradable, biodegradable, compostable and oxo-degradable describe 4 different things: degradable means the material breaks into smaller pieces, biodegradable means micro-organisms convert it to CO2, water and biomass, compostable means it does both under the conditions and inside the timeframe of EN 13432, and oxo-degradable means an additive drives the first step by oxidation. The four terms sit on one axis of increasing proof. Degradable proves nothing about the fate of the carbon, biodegradable names a biological process without stating where or how fast, compostable attaches a measured threshold to a named environment, and oxo-degradable is the only one of the four that is a legal term in the EU.

One rule follows from that axis and governs every later section here. European Commission communication COM(2022) 682 requires a biodegradability claim to specify the receiving environment and the timeframe, and allows no such claim on litter-prone single-use plastic products. A bare claim of "biodegradable" is therefore unusable in the EU, and every statement on this page names the environment (industrial compost, home compost, soil, sea water, open air) and the period measured.

Table T2. The 4 terms and what each one requires.

Which polymers can a biodegradation additive degrade?#

The polymer decides which additive can work: pro-oxidant additives act on polyethylene and polypropylene because polyolefin chains oxidise, while enzymatic additives act only on polyesters such as PLA and PCL, since polyolefins do not associate with enzymes at all. That boundary is chemistry, not formulation preference. Christopher DelRe, Ting Xu and colleagues at the University of California, Berkeley reported in Nature in 2021 that polyolefins do not associate with enzymes.

The 3 polymer groups and the chemistry that can act on each are listed below.

• Polyolefins (polyethylene, polypropylene), which oxidise readily and therefore respond to iron, manganese and cobalt carboxylates, and which no enzyme attacks
• Aliphatic polyesters (PLA, PCL), which carry hydrolysable ester bonds and are the only polymers in which hydrolase enzymes have produced near-complete conversion in peer-reviewed work
• PET, an aromatic polyester tested with organic biodegradation promoters by Susan Selke, Rafael Auras and colleagues at Michigan State University, with no significant increase in biodegradation in compost, in anaerobic digestion or in soil (Environmental Science & Technology, 2015)

No additive in this family makes polyethylene or polypropylene biodegradable in any environment on any published timeframe.

5 Types of Biodegradation Additives#

The 5 types of biodegradation additives sold for plastics are pro-oxidant (oxo) masterbatches, biotransformation additives, organic biodegradation promoters, enzymatic additives, and photodegradable additives and copolymers. The order runs from the largest and most regulated class to the smallest, keeping the three polyolefin routes together before the polyester route and the ultraviolet route. It also runs from the weakest evidence to the strongest, so the evidence section repeats the same sequence.

1. Pro-oxidant (oxo) masterbatches#

Pro-oxidant masterbatches are transition-metal carboxylates, usually iron, manganese or cobalt stearates, that catalyse the decomposition of hydroperoxides in polyethylene and polypropylene once the antioxidant package is used up. The metal cycles between two oxidation states, splits a hydroperoxide into radicals, and each split ends in a chain scission. The function is the inverse of stabilization: the hydroperoxide chemistry an antioxidant suppresses is the chemistry a pro-oxidant accelerates.

The class is sold as a concentrate for polyethylene and polypropylene film and moulded articles, at a stated inclusion rate of 1 % for the d2w masterbatch according to its supplier, Symphony Environmental, and at 2 % w/w in the published PAC studies. Products made from oxo-degradable plastic have been prohibited in the EU since 3 July 2021 under Article 5 of Directive (EU) 2019/904, which makes this the only class in the family whose finished articles cannot be placed on an EU market. The full record for oxo-degradable plastics, study by study and country by country, sits on its own page.

Which metal stearates work as pro-oxidants: cobalt, manganese and iron?#

Three metal stearates carry the pro-oxidant function in commercial masterbatches: iron, manganese and cobalt, ranked iron < manganese < cobalt by pro-oxidant strength after photo-thermal treatment of LDPE (Abrusci and colleagues, reported in the 2023 Royal Society Open Science review). A second experiment gives a different order because it measures a different endpoint. Konduri and colleagues exposed LDPE containing pro-oxidant stearates to ultraviolet light and then to the fungus Aspergillus oryzae in 2011, and measured tensile-strength decreases of 51 % for manganese, 45 % for titanium, 40 % for iron and 39 % for cobalt, with manganese stearate also giving a 62 % elongation decrease.

The two rankings are not interchangeable: the first ranks catalytic activity after photo-thermal treatment alone, the second ranks mechanical damage after a combined ultraviolet and fungal exposure. One of the three metals carries its own record here: identity, classification and food-contact status of cobalt stearate, CAS 13586-84-0, EC 237-016-4. Iron(III) tristearate is CAS 555-36-2, and our source library holds no CAS number for manganese stearate.

2. Biotransformation additives and the PAS 9017 route#

Biotransformation additives are the successor class to oxo masterbatches: they aim at the endpoint written into PAS 9017:2020, which requires the polymer to fall below 5,000 Da number-average molecular weight and below 30,000 Da z-average molecular weight, and to lose more than 90 % of its weight-average molecular weight, measured by gel permeation chromatography after accelerated weathering. The weathering step runs 14 days for films and 28 days for rigid articles. The class differs from class 1 not in chemistry, which its suppliers do not disclose, but in committing to a numerical abiotic endpoint a laboratory can check.

That endpoint is demanding. Measured biodegradability of pro-oxidant additive containing plastics in the literature spans 5 to 60 %, according to the 2023 Royal Society Open Science review by Fabiola Sciscione, Helen Hailes and Mark Miodownik at University College London, so most formulations in that literature would not pass PAS 9017:2020. Our records hold no supplier, no dosage and no independent test result for any product marketed as a biotransformation additive, so no company is named here.

3. Organic biodegradation promoters for polyethylene and PET#

Organic biodegradation promoters are non-metal additives sold for polyethylene and PET on the claim that they attract micro-organisms to the polymer, and the largest independent test of them found no measurable effect. Susan Selke, Rafael Auras and colleagues at Michigan State University tested 5 biodegradation-promoting additives in polyethylene and PET across three receiving environments, compost, anaerobic digestion and soil, and reported no significant increase in biodegradation in any of them (Environmental Science & Technology, 2015).

This is the class most of the vendor pages ranking for "biodegradable additive for plastic" actually sell, which makes that result the most important number on this page for a buyer. No peer-reviewed study in our source library shows a positive effect for the class in any environment on any timeframe, and our records name none of the 5 products tested. The class is dosed into polyethylene alongside a conventional stabilizer package, and the package that has to be consumed first is described on additives for polyethylene.

4. Enzymatic additives for PLA, PCL and other polyesters#

Enzymatic additives are hydrolase enzymes dispersed in a polyester so that the article depolymerises itself, and they are the only class in this family with peer-reviewed evidence of near-complete conversion. Grade and processing data for enzymatic biodegradation additives are collected on the page for this route. The enzyme cleaves the ester bond directly, which is why the class works in polyesters and nowhere else.

Marie Guicherd, Alain Marty and colleagues at Carbios engineered a PLA hydrolase with an 80-fold activity gain and published it in Nature in 2024. The processing route is the point of the result: the enzyme enters the article through a polycaprolactone masterbatch compounded at 70 °C and only then into PLA at 160 °C, which is what allows a protein to survive an industrial melt. At 0.02 % w/w enzyme in the film, the material disintegrated under home-compost conditions within 20 to 24 weeks.

A second route reaches the same endpoint differently. Christopher DelRe, Ting Xu and colleagues at the University of California, Berkeley dispersed enzymes at below 2 wt% in PCL and PLA and reported up to 98 % conversion of the polymer to small molecules within days in soil compost and in tap water (Nature, 2021). Both results are laboratory work on polyesters, not on polyolefins, and the rest of the package for that polymer is on additives for PLA.

5. Photodegradable additives and copolymers#

Photodegradable additives and copolymers use ultraviolet light, not heat and oxygen, as the trigger, which ties their performance to field exposure rather than to any waste-treatment process. An article in a bin, a landfill or a closed composting vessel receives no ultraviolet dose, so the trigger is absent exactly where most plastic ends its life.

Our source library holds no dosage, no commercial grade and no measured degradation result for this class, so no number is given for it anywhere on this page. Field exposure and film life are the governing variables, and both are covered on additives for agricultural film.

How Do Pro-Oxidant Additives Work? The Two-Stage Model#

Pro-oxidant additives work in 2 stages: an abiotic stage in which the metal carboxylate decomposes hydroperoxides, cuts the chains and embrittles the article, and a biotic stage in which micro-organisms are expected to assimilate the oxidised fragments. The two stages are separated by the physical state of the material, not by a fixed period, and the evidence behind them is asymmetric: stage 1 is reproducible in the laboratory, stage 2 is where the published record thins out.

The 2 stages run in this order.

1. Oxidise the polymer abiotically, once the antioxidant package is consumed, until chain scission drops the molecular weight far enough for the article to break into fragments
2. Assimilate those fragments biotically, which requires micro-organisms to convert the oxidised carbon to CO2, water and biomass in a named environment within a stated period

Stage 1: abiotic oxidation, chain scission and fragmentation#

Stage 1 begins when the antioxidant package is exhausted: the metal carboxylate then splits hydroperoxides into radicals, each split cuts a chain, and the polymer loses molecular weight until the article is brittle enough to break into fragments. Iron, manganese and cobalt salts accelerate photo-oxidation by hydroperoxide homolysis, which is the same reaction a phenolic antioxidant and a phosphite exist to prevent. The period before that reaction starts is the induction period, and its length is set by how much stabilizer has to be consumed first.

Three measurable signals track the stage. Carbonyl groups accumulate as oxidation products, and oxidation is tracked by the carbonyl index measured by infrared spectroscopy. Molecular weight falls, which PAS 9017:2020 quantifies as a drop below 5,000 Da number-average and below 30,000 Da z-average, with a loss of more than 90 % of the weight-average value. Mechanical properties collapse in step with both: in the Konduri 2011 exposure of LDPE, tensile strength fell by 39 to 51 % depending on the metal.

Fragmentation ends stage 1. An article in that state satisfies the first half of the EU definition of oxo-degradable plastic, has produced micro-fragments, and has lost no carbon to biology.

Stage 2: biotic assimilation, and where the evidence stops#

Stage 2 is where the claim and the evidence separate: the European Commission concluded in its 2018 report COM(2018) 35 that no conclusive evidence shows full biodegradation of oxo-degradable plastic in any open environment, and that the material is not suitable for composting or for anaerobic digestion. That conclusion concerns the second stage only, since nobody disputes that the first stage happens.

The measured range explains the conclusion. Biodegradability of pro-oxidant additive containing plastics reported across the peer-reviewed literature runs from 5 to 60 %, as collected in the 2023 Royal Society Open Science review by Sciscione, Hailes and Miodownik at University College London, and within that same review the highest single soil result is 91 % biodegradation of LDPE containing manganese stearate after 753 days, reported by Jakubowicz. The 91 % figure is the top of that distribution, not its centre, and quoting it without the 5 to 60 % range and without the 753-day exposure converts a laboratory maximum into a product claim.

What remains after stage 1 in most reported cases is oxidised polymer fragments of reduced molecular weight, which is why the regulatory sections below treat fragmentation and biodegradation as separate legal facts.

How biodegradation additives interact with antioxidants, UV stabilizers and other stabilizers#

A pro-oxidant additive and a stabilizer package pull in opposite directions: the additive cannot act until the antioxidants are consumed, so the antioxidant and light-stabilizer levels, not the pro-oxidant level alone, set how long the article stays intact. The package that sets the induction period is described on antioxidants for plastics, and a formulator who raises the phenolic or phosphite level to protect the melt has, by the same act, extended the time before any degradation begins.

Table T4. Additive families that oppose a biodegradation additive.

Light stabilizers are the strongest opponent in outdoor use. HALS and ultraviolet absorbers work the other way, as UV stabilizers for plastics shows, and an agricultural film formulated for two seasons of field service carries exactly the package that suppresses the pro-oxidant for two seasons.

No single number therefore describes when an article containing a biodegradation additive begins to degrade: the pro-oxidant level is one input, and the antioxidant level, the light-stabilizer level, the pigment and the service environment are the others.

How Much Pro-Oxidant or Enzyme Is Used? Masterbatch Dosage#

Biodegradation additives are dosed between 0.02 % w/w for an engineered enzyme in PLA film and 2 % w/w for a pro-oxidant masterbatch in the published studies of pro-oxidant additive containing plastics, with the supplier of d2w stating a 1 % inclusion rate for polyethylene and polypropylene. Every figure in this family carries its provenance, because supplier inclusion rates and study dosages are not the same kind of number: the first is a recommendation, the second is what a published experiment measured.

Table T3. Dosage by class, with the source type of each number.

None of these actives reaches the machine as a neat powder. The pro-oxidant arrives as a masterbatch and is let down at the machine, which is why a 1 % inclusion rate describes the concentrate in the article rather than the metal content: the active carboxylate is a fraction of that 1 %. The enzymatic route uses the same principle for a different reason, since the polycaprolactone carrier compounded at 70 °C protects the protein from the 160 °C PLA melt.

What Does the Evidence Say? 6 Landmark Studies#

Six studies and one Commission report define what is known: fragmentation of oxo-treated polyolefins is reproducible, full biodegradation in an open environment has not been demonstrated, organic promoters showed no effect in polyethylene or PET, and engineered enzymes converted up to 98 % of a polyester to small molecules within days. The studies below carry numbers rather than positions, and they are listed in the order they were published. Two are laboratory work on the pro-oxidant route, one is a field exposure of finished bags, two are enzyme studies in polyesters, and one is a review collecting the whole PAC distribution. A fragmentation result, a percentage biodegradation and a disintegration time are three different measurements, and vendor claims on this topic routinely present the first as if it were the second.

Table T5. The evidence base, in chronological order.

Does oxo-degradable plastic fully biodegrade?#

No study in the peer-reviewed record demonstrates full biodegradation of oxo-degradable plastic in an open environment, which is also the conclusion of the European Commission's 2018 report COM(2018) 35. The distribution of measured values explains why: biodegradability of pro-oxidant additive containing plastics reported in the literature runs from 5 to 60 %, and the single highest soil value, 91 % for LDPE with manganese stearate, took 753 days.

Field work on finished articles gives the same split between fragmentation and biodegradation. Imogen Napper and Richard Thompson at the University of Plymouth exposed carrier bags in sea water, in soil and in open air for more than 27 months and published the result in Environmental Science & Technology in 2019. Every bag type tested disintegrated in open air within 9 months, which is a fragmentation result. The compostable bag behaved differently in the other two environments: it disappeared in sea water within 3 months and was still present in soil after 27 months. The lesson is not that one bag type works and another does not, but that the receiving environment governs the outcome for the same material. Sea-water results are collected on plastic additives in the marine environment.

Do biodegradation-promoting additives work in polyethylene?#

No: in the largest independent test, 5 biodegradation-promoting additives in polyethylene and PET produced no significant increase in biodegradation in compost, in anaerobic digestion or in soil (Susan Selke, Rafael Auras and colleagues at Michigan State University, Environmental Science & Technology, 2015). Three receiving environments in one study design is what makes the result hard to argue with, since a null result in a single environment can always be blamed on that environment.

Our source library does not record which 5 products were tested, so no commercial name is attached to that outcome on this page. The finding is class-level: an organic biodegradation-promoting additive in polyethylene or PET did not measurably change how much of the polymer carbon micro-organisms converted in compost, anaerobic digestion or soil. A buyer evaluating a product in this class has one reasonable request, an independent test in the receiving environment the claim names, over the timeframe the claim states.

Do enzymatic additives work in PLA?#

Yes, in polyesters: an engineered PLA hydrolase at 0.02 % w/w disintegrated PLA film under home-compost conditions within 20 to 24 weeks (Marie Guicherd, Alain Marty and colleagues at Carbios, Nature, 2024), and nano-dispersed enzymes below 2 wt% converted up to 98 % of PCL and PLA to small molecules within days (Christopher DelRe, Ting Xu and colleagues at the University of California, Berkeley, Nature, 2021). Both results are large, and both are bounded by the polymer.

The comparison that gives them meaning is PLA without an enzyme. In industrial composting at 58 °C, about half of a PLA article decomposes in 60 days, and full degradation requires above 60 °C, which a garden heap does not reach. The enzymatic route moves PLA from industrial composting into home-compost conditions on a 20 to 24 week timeframe.

The boundary condition comes from the same Nature work of 2021: polyolefins do not associate with enzymes. Polyethylene and polypropylene are outside this route entirely, and no dose of any hydrolase changes that.

How Is Biodegradation Tested and Certified?#

Biodegradation is measured as the percentage of the polymer's carbon converted to CO2 under defined conditions, and 3 standard families cover the field: composting standards such as EN 13432, oxidative-degradation standards such as PAS 9017:2020, and aquatic certification criteria such as OK Biodegradable WATER. Each family answers a different question, and none answers all three questions a claim raises: how much carbon, in which environment, over what period. A certification is therefore never transferable, since a material certified for industrial composting was tested in a heated vessel, and that result says nothing about soil, sea water or a domestic heap. The table sets out what each standard measures and what it leaves open, and every method is indexed under testing plastic additives.

Table T6. The standards, their criteria and their limits.

EN 13432, ASTM D6400 and industrial composting#

EN 13432 sets 4 conditions for industrial compostability: at least 90 % biodegradation within 6 months measured under EN 14046, disintegration to less than 10 % residue after 3 months of pilot composting under EN 14045, heavy metals below the listed maxima, and no ecotoxic effect on plants. Those four conditions together are what "compostable" means in the EU. Each alone is insufficient: a material can disintegrate without biodegrading, and it can biodegrade while carrying a metal load that disqualifies the compost.

The heavy-metal table of EN 13432 is an open item in our records, so this page states the criterion and prints no numbers for it. Temperature is the condition most often overlooked: industrial composting runs hot, and PLA at 58 °C decomposes about half of its mass in 60 days, with full degradation requiring above 60 °C. A domestic heap does not reach that temperature, which is why home compostability is certified separately rather than inferred from EN 13432.

ASTM D6400 and ASTM D6868 are the US specifications for compostable plastics. Their criteria are not verified against a primary source on file, so no threshold is quoted for them, and the EN 13432 figures above are the only composting thresholds this page states as fact.

ASTM D6954, PAS 9017 and the oxo standards#

PAS 9017:2020 is the only oxidative-degradation standard for which our source library holds a quantified criterion, and that criterion is abiotic: number-average molecular weight below 5,000 Da, z-average below 30,000 Da, and a loss of more than 90 % of the weight-average molecular weight by gel permeation chromatography after accelerated weathering. Reaching a molecular-weight endpoint measures how far the polymer has been cut up, not how much of its carbon micro-organisms have consumed.

Most published formulations would not reach it. Measured biodegradability of PAC plastics in the literature spans 5 to 60 %, and the 2023 Royal Society Open Science review by Sciscione, Hailes and Miodownik concludes on that basis that most of them would not pass PAS 9017:2020.

Symphony Environmental, the supplier of the d2w masterbatch, cites 6 standards for its product, listed below.

• BS 8472
• ASTM D6954
• UAE 5009:2009
• AFNOR T51-808
• SASO 2879
• NMX-E-288-NYCE

These are standards the supplier cites, not independent certifications that the material biodegrades in a named environment within a stated period. Whether the United Arab Emirates and Saudi standards in that list still require oxo additives in 2026 is unverified, so neither is described as a current mandate.

Where Are Biodegradation Additives Banned, and What Can You Claim?#

Products made from oxo-degradable plastic are prohibited across the EU since 3 July 2021 under Article 5 of Directive (EU) 2019/904, and in the United States the additive is not banned while the claim is regulated, by the FTC Green Guides at federal level and by California Public Resources Code 42357 at state level. The distinction between prohibiting a product and prohibiting a claim runs through every row of the table below, and it decides what a compounder can sell and what a brand owner can print. A masterbatch that is legal to manufacture and ship can make the article it is dosed into unmarketable in the EU, and can be sold freely in the United States while the sentence describing its purpose is a deceptive claim. All instruments are summarised in plastic additive regulations.

Table T7. Status by jurisdiction.

Further jurisdictions are listed on the oxo-ban page for this family.

EU: the oxo ban under Directive (EU) 2019/904 and the Symphony judgment#

The EU prohibition covers products, not the additive as a chemical: Member States must prohibit placing on the market products made from oxo-degradable plastic, applicable since 3 July 2021 under Article 5 and Article 17 of Directive (EU) 2019/904. The legal hook is Article 3(3), which captures any plastic containing additives that lead, through oxidation, to fragmentation into micro-fragments or to chemical decomposition.

The marketing term creates no exemption. In Symphony Environmental v Parliament and Others (Case T-745/20, judgment of 31 January 2024), the General Court dismissed the action for damages and held that the prohibition lawfully makes no distinction between oxo-degradable and oxo-biodegradable plastic. A product sold as oxo-biodegradable is inside the ban exactly as one sold as oxo-degradable is, and the jurisdiction-level detail is collected on oxo-degradable plastic bans.

A separate EU rule governs the words rather than the product. Commission communication COM(2022) 682 requires a biodegradability claim to specify the receiving environment and the timeframe, and permits no such claim on single-use plastic products prone to being littered. It attaches to the claim, not the chemistry, so it covers compostable polymers as well.

Packaging carries a second deadline on top of the ban. The EU Packaging and Packaging Waste Regulation (PPWR), Regulation (EU) 2025/40, applies from 12 August 2026: Article 9(1) requires permeable tea and coffee bags, soft single-serve units and fruit and vegetable stickers to be compostable by 12 February 2028, and Article 9(3) requires other biodegradable-plastic packaging to be designed for material recycling by the same date.

US: the FTC Green Guides and California's claim rules#

In the United States the additive is legal and the claim is not: under 16 CFR 260.8 an unqualified degradable claim is deceptive unless the item completely decomposes within one year after customary disposal, and the section names oxo-degradable and oxo-biodegradable claims expressly. "Customary disposal" is the decisive phrase, because for most packaging it means a landfill, an incinerator or a recycling facility, and none of those routes supports an unqualified degradable claim.

California goes further and prohibits the words themselves. Public Resources Code 42357 prohibits labelling a plastic product "biodegradable", "degradable" or "decomposable", or implying that it will break down, without reference to whether the performance claim behind it could be substantiated. A compounder can lawfully sell a pro-oxidant masterbatch in the United States while the converter who uses it cannot lawfully print the word that describes what it is meant to do.

The US position has 3 layers: the additive is unrestricted, the unqualified claim is deceptive under federal law without demonstrated one-year decomposition, and the words themselves are prohibited on plastic products in California.

Are Pro-Oxidant Additives Allowed in Food-Contact Plastic?#

The metal stearates used as pro-oxidants are covered for food-contact plastics in the EU through the salt rule in Article 6(3)(a) of Regulation (EU) No 10/2011, and they remain subject to the Annex II metal limits of 0.05 mg/kg food for cobalt, 0.6 mg/kg food for manganese and 48 mg/kg food for iron. The salt rule is indirect: it covers salts of authorised acids, phenols and alcohols with the metals marked "yes" in Annex II Table 1, a list that includes cobalt, copper, iron and manganese. Stearic acid is the authorised acid, FCM No 106 (reference 24550), which brings the three stearates inside the regulation without any of them holding an entry of its own.

Table T8. Food-contact status of the three pro-oxidant metals in the EU.

Two questions are answered here and they have different answers, which is the exact point at which supplier statements about food contact mislead. The substance question asks whether a metal stearate is covered for use in a plastic food-contact material: in the EU the answer is yes, through the salt rule and within the migration limits above, explained on EU 10/2011. The product question asks whether the finished article may be placed on the EU market: where that article is made from oxo-degradable plastic the answer is no, under Article 5 of Directive (EU) 2019/904, since 3 July 2021. A compliant substance inside a prohibited product is still a prohibited product.

How Do You Choose Between Oxo, Enzymatic and Compostable Routes?#

Choose between the routes in 5 steps: name the receiving environment and the timeframe the claim will state, check market access in every target country, match the polymer to the chemistry, check what the waste system actually does with the article, then decide between an additive and a compostable polymer. The order matters: steps 1 and 2 disqualify more projects than step 3 does, and both cost less than any trial.

1. Name the receiving environment and the timeframe the claim will state, since COM(2022) 682 requires both
2. Check market access in each target country, which removes any oxo-degradable article from the EU under Article 5 of Directive (EU) 2019/904 and unqualified degradable wording in the United States under 16 CFR 260.8
3. Match the polymer to the route, since polyolefins exclude the enzymatic route and polyesters are not the pro-oxidant substrate
4. Check what the end-of-life system does with the article, since COM(2018) 35 found oxo-degradable plastic unsuitable for composting and anaerobic digestion
5. Decide between an additive and a compostable polymer, then verify by the standard named in step 1, which for industrial compostability means the EN 13432 thresholds

If the answer at step 5 is a compostable polymer, the formulation work moves to a different family: see additives for biodegradable and compostable plastics, where chain extenders and nucleating agents carry the decisions.

The general framework is on how to select plastic additives. What this family adds is the legal filter at step 2, which no other additive class requires before a trial.

Who Supplies Biodegradation Additives?#

The supply side of this family is small and brand-led: the pro-oxidant route is sold under masterbatch trade names such as d2w from Symphony Environmental and TDPA from EPI, while the enzymatic route comes from the biotechnology side, where Carbios developed the engineered PLA hydrolase used in the 2024 Nature study. TDPA, Totally Degradable Plastic Additives, is a trade name for an oxo pro-oxidant masterbatch rather than a single substance, and its supplier status is unclear in our records.

Company profiles sit in the directory of plastic additive manufacturers and suppliers, which covers the compounders and masterbatch houses that turn these actives into concentrates. The organic biodegradation promoter segment is the most crowded part of the family by sellers and the thinnest by published evidence, and no company in it is named here, because our source library holds no verified supplier record for those products.

No market-size figure for this family is held in our source library, so none is quoted. The segment is small against the 43 additive families, concentrated in a handful of brand-led suppliers, and constrained by the EU prohibition that closed its largest regulated market in 2021. Segment figures for the families that have them are on plastic additives market.

Substances Used as Biodegradation Additives#

The chemistry of this family reduces to 3 groups: metal carboxylates for the pro-oxidant route, hydrolase enzymes for the polyester route, and proprietary organic blends whose composition suppliers do not disclose. Only the first group resolves into named substances with CAS numbers, which is itself a finding about the family.

Table T9. Substances and substance classes used as biodegradation additives.

Each metal salt has its record in the plastic additives database, where CAS and EC numbers, food-contact status and regulatory entries are held per substance rather than per family.

Do Biodegradation Additives Help or Harm the Plastics Circle?#

The circular-economy objection to this family has 2 parts: an article designed to fragment adds microplastic-sized pieces to the environment, and the same additive downgrades the recyclability of the package it is in. Both attach to the additive itself rather than to any supplier, which separates this debate from an ordinary product dispute.

The 2 objections are stated below.

• Micro-fragment release, since the EU definition of oxo-degradable plastic describes fragmentation into micro-fragments as the designed outcome, and the measured biodegradation range of 5 to 60 % leaves the remainder in that fragmented state
• Recyclability loss, since the Association of Plastic Recyclers design guidance classes a polypropylene package containing degradable (oxo) additives as non-recyclable

The wider argument, across all 43 additive families rather than this one, is on plastic additives in a circular economy.

Do biodegradation additives create microplastics?#

Fragmentation into micro-fragments is the stated mechanism, not a side effect: the EU definition of oxo-degradable plastic in Article 3(3) of Directive (EU) 2019/904 describes exactly that outcome, and the 2023 University College London review by Fabiola Sciscione, Helen Hailes and Mark Miodownik documents microplastic formation in pro-oxidant additive containing plastics. An additive whose function is to embrittle a polymer until it breaks apart produces small pieces by definition.

Whether those pieces persist is the second question, and the measured range answers it: at 5 to 60 % biodegradation, 40 to 95 % of the material stayed as polymer fragments. Fragment sizes and the leaching behaviour that follows are covered by microplastics and additive leaching.

How do biodegradation additives affect plastic recycling?#

A degradable additive removes a package from the recycling stream: the Association of Plastic Recyclers design guidance classes a polypropylene package containing oxo additives as non-recyclable. The reason is carry-over. Oxidised, chain-scissioned material entering a recyclate takes its reduced molecular weight and its pro-oxidant metal with it, and the next article made from that stream inherits both.

The rule is one of the entries on design for recycling, where density windows, colour limits and layer structures decide the same question for other families. A recycler cannot detect a pro-oxidant masterbatch by near-infrared sorting, which is why the guidance excludes the package at the design stage rather than at the sorting stage.

EU law points the same way. Article 9(3) of Regulation (EU) 2025/40 requires biodegradable-plastic packaging to be designed for material recycling by 12 February 2028, placing a recyclability duty on exactly the packaging this family targets. Restabilizing a contaminated stream is covered on additives for recycled plastics.

Biodegradation additive FAQs#

Is oxo-biodegradable plastic biodegradable?#

No published study in the peer-reviewed record demonstrates that oxo-biodegradable plastic biodegrades completely in an open environment, and the EU General Court confirmed in Case T-745/20 on 31 January 2024 that the marketing term creates no legal distinction from oxo-degradable plastic. The European Commission reached the same technical conclusion in COM(2018) 35 in 2018. Measured values in the literature run from 5 to 60 % biodegradation, with a single soil maximum of 91 % after 753 days.

What is the difference between biodegradable and compostable plastic?#

Compostable is the measurable version of biodegradable: a compostable plastic passes EN 13432, which requires at least 90 % biodegradation within 6 months and less than 10 % residue after 3 months of industrial composting, while "biodegradable" alone names neither an environment nor a timeframe. That is why COM(2022) 682 requires every biodegradability claim to state the receiving environment and the period, and why California Public Resources Code 42357 prohibits the bare word on a plastic product.

How long does oxo-degradable plastic take to break down?#

Fragmentation and biodegradation run on different clocks: in the University of Plymouth study by Imogen Napper and Richard Thompson, bags of every type tested disintegrated in open air within 9 months, while the highest published soil result for an oxo formulation is 91 % biodegradation of LDPE with manganese stearate after 753 days. Against that single maximum, the literature range is 5 to 60 % biodegradation. No figure in this family means anything without its environment attached, because the same bag behaved differently in open air, in soil and in sea water.

Which chemical can decompose plastic?#

Enzymes decompose plastics, but only polyesters: engineered hydrolases converted up to 98 % of PCL and PLA to small molecules within days in soil compost and tap water, while metal carboxylates oxidise polyethylene and polypropylene into fragments rather than decomposing them. The 98 % figure comes from DelRe, Xu and colleagues at the University of California, Berkeley (Nature, 2021), and the same work reports that polyolefins do not associate with enzymes at all.