Clarifying the Taxonomy of Plastics and Bioplastics: Toward a ‘Zero-Trace Plastic’ (ZTP) Material Framework

Abstract

The lack of precise definitions in plastics-related terminology continues to hinder the development of coherent sustainability strategies across the materials value chain. This communication revisits current definitions of plastics, polymers, and bioplastics, distinguishing between source (bio-based vs. fossil-based), structure (synthetic vs. natural polymer), and degradation behaviour (persistent vs. compostable or biodegradable). It critiques ambiguous classifications promoted in policy and marketing discourse. It introduces the concept of “Zero-Trace Plastic” (ZTP) to refer to materials that are non-plastic substitutes intended for versatile plastic-like uses while guaranteeing no trace of synthetic plastics in their composition and no contribution to pollution across their lifecycle. The ZTPframework prioritises complete mineralisation without plastic or microplastics or chemical residues under real-world conditions. ZTP is proposed not as a replacement for existing biodegradability standards, but it helps distinguish between plastic and non-plastic biopolymers and works as a complementary benchmark for biodegradability that aligns with and extends them by incorporating environmental specificity and system-wide traceability. The paper proposes a harmonised terminology matrix and calls for coordinated efforts by international agencies and standardisation institutes, national bodies and industries to avoid using misleading terminologies like bioplastics, often used for greenwashing and to enhance circular material strategies.

1. Introduction

The recent innovations in bioplastics and biopolymers bring new challenges to the application. Bio-based plastics, commonly referred to as ‘bioplastics’ (typically plastics manufactured from bio-based polymers), have been introduced primarily to reduce the fossil carbon footprint associated with plastic production, not necessarily to address plastic pollution, as bioplastics lower carbon footprints by up to 42% and consume 65% less energy during production compared to traditional petroleum-based plastics [1].

However, bioplastics are often referred to as a solution to plastic pollution [2,3], especially relating to biodegradability and compostability rates in the natural environment compared to the typical fossil-based plastics, which might not be the case, as the study found around 60% of certified home-compostable plastics did not degrade effectively in actual home composting conditions [4]. The confusion arises from the fact that biopolymers are often categorised using the same framework as bioplastics, namely, as either bio-based and non-biodegradable, bio-based and biodegradable, or fossil-based and biodegradable. Due to these confusions, the International Union of Pure and Applied Chemistry (IUPAC) has suggested not to use the term “bioplastic” [5]. The confusion around the terminologies has been reported in several articles [6,7]; however, no new terminology was put forward to overcome these challenges and confusions.

Unfortunately, due to a lack of precise terminology, consumers often misclassify materials during household sorting, for instance, treating compostable materials as recyclable, which leads to contamination in reverse logistics chains. Part of this confusion arises from the indiscriminate use of the term “bioplastics” to describe both naturally occurring biopolymers and industrially synthesised bio-based polymers. Naturally derived polymers such as cellulose, starch, chitosan, casein, and soy protein are produced by organisms in nature and lack the long-chain synthetic backbones typical of fossil-derived and industrially processed bio-based plastics. These materials, owing to their biological origin and degradation profiles, are more accurately classified as biopolymers rather than plastics [8,9,10,11].

In contrast, materials like bio-PE, bio-PET, and PLA, though derived from renewable feedstocks such as glucose, are chemically synthesised through industrial pathways (glucose → ethanol → ethylene → polyethylene or PET; glucose → lactic acid → PLA). These are best understood as bio-based polymers, not biopolymers, given their synthetic nature and persistence in the environment [12]. Clarifying these definitions is crucial for effective communication, informed policy development, and accurate consumer guidance.

The study also considers the definitional discourse presented by the coalition of scientists contributing to the Plastics Treaty, whose work highlights key considerations in differentiating plastics, alternatives, and substitutes. Their rigorous approach to classification provides an essential framework for understanding the complexities surrounding biopolymer terminology and its implications in policy, industry, and household practices. Given the widespread inconsistencies in terminology, it is essential to clarify how standard material terms relate to one another based on their carbon source, polymer structure, degradation behaviour, and standard usage.

Table 1. Classification matrix of plastics, bioplastics, and biopolymers by carbon source, structure, and degradability.

Term	Carbon Source	Polymer Structure	Degradability	Examples	References
Plastic.	Fossil or bio-based.	Synthetic, long chain.	Often persistent.	PE, PET, PS.	ISO 472:2013 [13].
Bioplastic.	Bio or fossil-based.	Synthetic.	Varies (PLA versus bio-PE).	PLA, bio-PE, PBAT.	European Bioplastics [14], IUPAC [15].
Biopolymer.	Natural (Bio-based).	Produced by organisms.	Typically biodegradable.	Starch, PHA, chitosan.	IUPAC [15], academic sources [16,17,18,19,20,21,22,23,24,25,26,27].
Compostable Plastic.	Fossil or bio-based.	Synthetic or blended.	Degradable in industrial conditions.	PLA, PBAT.	ASTM D6400 [28], EN 13432 [29].
Zero-Trace Plastic (ZTP).	Bio-based.	Engineered or natural.	Fully mineralising under target conditions.	PHA, future materials.	This study proposed a framework. *

Note: * Proposed in this study as a policy-oriented performance framework. Zero-Trace Plastic (ZTP) is the formal term used in this paper. “Non-pollutant plastic (NPP)” is also used in the paper, and can occasionally be used to describe the non-polluting characteristics of the materials, which might be commonly perceived in public or policy communications, to refer to similar concepts.

presents a comparative framework that disambiguates these categories using authoritative sources such as ISO, IUPAC, and European Bioplastics.

2. Materials and Methods

This communication brief draws on insights from researchers’ past projects (reflective synthesis), specifically research conducted mainly between January 2020 and March 2024, focused on plastic circularity, biopolymers, and circular economy transitions. Scopus was selected for its peer-reviewed academic rigour, while Google Scholar was included to capture relevant grey literature and policy briefs that may not appear in indexed journals. Reflective synthesis was used to identify recurring conceptual gaps encountered in prior stakeholder engagements and policy dialogues. The selection of this recent five-year window was deliberate, as the majority of studies on plastic substitution and emerging alternatives have been published in this period, marking a phase of rapid development in materials science and policy discourse. It was also evident in the literature [5,6,30] and available standards (including ASTM D6400, EN 13432, and EN 14995) that the absence of a clear taxonomy to distinguish between plastics and biopolymers, particularly in the generic application or references, confuses the terminology and warrants investigating new terminologies. Moreover, as this submission is a communication brief, the narrower temporal scope was intended to keep the analysis focused and targeted. Future studies may consider extending the review period to encompass a broader historical range, tracing the evolution and institutionalisation of these terminological challenges.

The authors acknowledge the intentionally flexible methodological orientation of this communication brief, which reflects the applied and exploratory nature of the inquiry. Rather than following a conventional empirical protocol, this contribution emerged from practice-based reflection during the authors’ engagement with international and national initiatives on plastic alternatives and substitutes. A recurring challenge encountered was the absence of a clear terminological distinction between materials that perform like plastics but do not contain polymeric structures derived from fossil or synthetic origins, which the authors propose to conceptualise as ZTP. This conceptual gap is not only theoretical but also has significant policy and operational implications. This approach is consistent with the normative aim of the communication brief: to propose a terminological clarification that is both actionable and policy-relevant, rather than a hypothesis-driven empirical study.

A targeted narrative review was conducted using Scopus and Google Scholar databases (keywords: “plastic”, OR “polymer”, OR “bioplastics”, OR “biopolymers”, AND “taxonomy”, OR “classification”) to examine inconsistencies in terminology. Based on this, a new taxonomy is proposed, structured around material origin, biodegradability, end-of-life potential, and alignment with circular economy principles.

3. Challenges of Common Taxonomy and Terminologies of Plastics, Polymers, and Biopolymers

Understanding the complexities of plastics and polymers is essential due to inconsistent definitions and overlapping categories commonly used and referred to in the industry (Figure 1). Polymers, the foundation of plastics, are large molecules formed by repeating structural units called monomers [30,31,32,33,34,35,36]. However, not all polymers can be classified as plastics [37]. Plastics, a subset of polymers, are usually synthetic and flexible, making them suitable for versatile applications. They can be categorised into two main types: (i) thermoplastics, which can be converted upon heating and (ii) thermosetting plastics, which permanently harden after processing [38,39]. According to the ISO 472:2013 standard, all plastic materials are defined as polymers [13]. This differentiation underscores the complexity of these materials, but the interchangeable use of terms like “polymer” and “plastic” often obscures these nuances, leading to misunderstandings.

Polymer materials are engineered with various additives to enhance their properties for specific applications, such as improving flexibility, durability, ultraviolet (UV) resistance, or flame retardancy [40]. These additives can include plasticisers, stabilisers, fillers, and colourants, and they are essential for optimising the performance of polymers across different industries. However, adding these substances creates significant complexities when the materials degrade. As polymers break down, the chemical remnants of these additives can leach into the environment, leading to potential pollution and raising concerns about toxicity. Additionally, the variability in additive formulations results in significant differences in the behaviour and characteristics of the materials, which also complicates their recycling and adherence to standards. For example, pure high-density polyethylene (HDPE) differs substantially from HDPE modified with stabilisers or fillers, affecting its degradation profile, mechanical properties, and recyclability. This variability complicates efforts to categorise and manage polymers effectively because the same base material can exhibit vastly different environmental and functional characteristics depending on its additive composition.

Bioplastics, or bio-based plastics, which are derived from biological resources such as sugarcane or starch, introduce additional complexity to the discussion surrounding plastics, including their additives [41]. While bioplastics are often marketed as environmentally friendly, the term encompasses various materials, each with different properties and environmental impacts. Bioplastics can be categorised as bio-based and non-biodegradable, bio-based and biodegradable, or even fossil-based and biodegradable. Bio-based polyethylene (bio-PE) is produced from ethanol derived from biomass, such as sugarcane, which is chemically identical to traditional petroleum-based polyethylene [12]. While bio-PE comes from renewable sources, its durability and resistance to degradation contribute to plastic pollution, similar to conventional polyethylene. Other examples of non-biodegradable bioplastics include bio-based polyamide (bio-PA) [42], bio-based polyethylene terephthalate (bio-PET), and bio-based polypropylene (bio-PP) [12,43,44]. Bio-PET combines bio-derived ethylene glycol with terephthalic acid, while bio-PE uses bio-derived ethylene.

The term “bioplastics” is often used loosely, lacking a clear, standardised definition. It typically refers to plastics that are either bio-based, biodegradable, or compostable and may include up to 80% fossil-derived monomers, as in the case of bio-PET, which combines a bio-based ethylene glycol component with fossil-derived terephthalic acid. Bio-based plastics are derived from plant materials like corn, sugar beets, or potato starch but currently account for only about 1% of the plastics market. Despite ongoing research to increase the percentage of bio-based material, most bio-based plastics still contain fossil-based components. For instance, Coca-Cola’s PlantBottle™ PET originally contained approximately 20% bio-based content (bio-derived ethylene glycol), with the remainder from fossil-derived terephthalic acid. Later developments by the NaturALL Bottle Alliance [45] aimed to increase this to 100% bio-based content. Compostable plastics are designed to fully decompose under specific industrial conditions. However, these conditions are typically only available at specialised facilities, which are scarce [46]. In the absence of such facilities, compostable plastics often persist in the environment, breaking down into harmful microplastics, similar to conventional plastics.

These biomaterials [12] reduce the carbon intensity of the materials system and can integrate smoothly into existing recycling systems, yet they do not naturally decompose, raising concerns about downstream environmental sustainability. Although these bioplastics reduce reliance on fossil fuels during production, their resistance to decomposition poses challenges for waste management. The difference between biodegradable and compostable plastics adds another layer of complexity. Biodegradable plastics can break down into natural substances like water and carbon dioxide under specific environmental conditions. However, the degradation process may leave behind chemical residues or microplastics, particularly if the required conditions, such as those found in industrial composting, are not met. Compostable plastics, a subset of biodegradable materials, adhere to strict standards to ensure complete degradation within defined timeframes under controlled conditions. Misuse or misunderstanding of these terms and inconsistent labelling often mislead consumers, complicating waste management.

Certain biodegradable plastics derived from fossil fuels, such as polybutylene succinate (PBS) [47,48,49], polycaprolactone (PCL) [50], and polybutylene adipate terephthalate (PBAT) [51,52], illustrate how biodegradability can be engineered into synthetic polymers. For instance, PBS is synthesised from fossil-derived succinic acid and butanediol, making it suitable for packaging and agricultural films and offering favourable biodegradability under industrial conditions. PCL, derived from ε-caprolactone, is used in medical devices and drug delivery systems due to its compatibility with other polymers and its ability to degrade into benign byproducts. PBAT combines flexibility and durability, making it ideal for compostable bags and mulch films, although it still requires specific conditions for complete decomposition.

In contrast, genuinely renewable and biodegradable bioplastics, such as polylactic acid (PLA) [53] and polyhydroxyalkanoates (PHA) [54,55], represent significant advancements in sustainable materials. PLA is made from sugars through fermentation, which produces lactic acid that is then polymerised to create a material commonly used in packaging and disposable products. However, PLA requires high-temperature industrial composting facilities for proper degradation, which limits its environmental benefits in natural conditions. On the other hand, PHAs, which are produced by microorganisms as a form of intracellular energy storage, degrade more efficiently across a broader range of environments, making them a promising alternative for sustainable applications. Additionally, starch-based bioplastics, derived from natural sources like corn or cassava, offer another biodegradable option, although they often require additives to improve their functionality and durability [56].

Despite being marketed as sustainable alternatives to conventional plastics, bioplastics and compostable plastics present a range of environmental and health concerns that question their viability as eco-friendly solutions. One significant issue is toxicity. Although derived from plant-based sources, these materials still rely on various chemicals, many of which are hazardous. A 2020 study conducted in Germany and Norway found that most bioplastics and plant-based materials contain over 1000 chemical features, with some samples containing as many as 20,000 [57]. More concerningly, the study revealed that bioplastics exhibit toxicity levels comparable to conventional plastics. These findings highlight the urgent need for stricter regulation and comprehensive safety assessments to evaluate the chemicals used in all forms of plastic production.

Another concern is the environmental and carbon footprint of bioplastics and compostable plastics. Despite their perceived sustainability, these materials frequently have a more substantial environmental impact than conventional plastics [36]. Their production, particularly in the agricultural phase, generates significant greenhouse gas emissions. Additionally, when bioplastics end up in landfills rather than composting facilities, they produce methane, a greenhouse gas with a far greater warming potential than carbon dioxide. As a result, the overall climate impact of bioplastics and compostable plastics cansome cases, exceed that of traditional plastics.

The presence of per- and poly-fluoroalkyl substances (PFASs) in compostable plastics is another growing concern [58]. PFASs are widely used to enhance water and oil resistance in compostable food packaging. However, these substances persist in the environment and have been linked to serious health risks. When compostable plastics containing PFASs are processed in composting facilities, the chemicals can leach into the compost, contaminating the final product. A further issue is the lack of industrial composting infrastructure for properly degrading bioplastics and compostable plastics [59]. Most of these materials require high-temperature industrial composting conditions and are available in only a few locations. In cities without access to such facilities, these materials are frequently sent to landfills or incinerators, where they fail to break down as intended, instead contributing to pollution. This gap in waste management infrastructure significantly undermines the potential benefits of compostable plastics.

The production of bioplastics and compostable plastics is also highly resource-intensive [1,60]. Cultivating crops for bioplastic feedstocks requires vast amounts of fossil fuels, water, and arable land. These resources could otherwise be used for food production, raising concerns about the ethical and environmental trade-offs associated with expanding the bioplastics industry. The reliance on agricultural inputs further complicates the argument that bioplastics offer a more sustainable alternative to petroleum-based plastics.

These challenges indicate that while bioplastics and compostable plastics are often promoted as environmentally responsible solutions, their practical limitations, environmental trade-offs, and lack of appropriate infrastructure call their sustainability into question. Without significant regulatory reforms, improved waste management systems, and more sustainable production practices, their contribution to a circular economy remains limited. The allure of bioplastics and compostable plastics as eco-friendly alternatives is deceptive. Their environmental and health risks, combined with the lack of infrastructure to handle their disposal, make them far from a sustainable solution. It is crucial to address these challenges before they can be considered a viable alternative to conventional plastics.

3.1. Plastic Alternatives Versus Plastic Substitutes

The discussion around plastic and non-plastic materials often centres on their environmental impact (

Table 2. Key differences between plastic alternatives and plastic substitutes.

Aspect.	Plastic Alternatives (‘Better Plastic’)	Plastic Substitutes (‘Non-Plastic Materials’)
Composition.	May include plastics (bio-based, or biodegradable).	Does not include plastics; entirely non-plastic materials.
Environmental Goal.	Reduce reliance on virgin fossil-based plastics.	Eliminate plastics entirely, reduce downstream impact.
Examples.	PLA, PHA, bio-PET.	Paper, bamboo, glass, metals, jute.
End-of-Life.	Requires proper recycling or industrial composting facilities.	Often biodegradable, erodible recyclable.

). Non-plastic materials, such as glass and metal, are considered sustainable solutions, especially due to their reuse potential. However, the energy required for their production, their recyclability, and how they are managed at the end of their life introduce trade-offs that complicate their overall environmental profile [61,62,63]. Bioplastics and biodegradable plastics further blur these distinctions. At the same time, they may be derived from renewable resources. However, they can still exhibit characteristics similar to conventional plastics, which requires careful examination of their entire lifecycle and disposal methods. Unfortunately, inconsistencies in terminology to clearly distinguish between plastic and non-plastic have led to widespread misconceptions.

Labels such as “bioplastic” or “eco-friendly” often obscure the true environmental impact of materials, fostering distrust and instances of greenwashing. Additionally, bioplastics may only sometimes fit into traditional recycling systems, leading to contamination and inefficiencies. These challenges highlight the urgent need for clear definitions and standardised frameworks. Such clarity is not merely important, consumers need to make informed choices, policymakers need to create effective regulations, and manufacturers need to align with sustainability goals.

Despite the unsuccessful global plastic treaty, the initiative generates innovative ideas and solutions not only on how to better manage end-of-life plastic but also to find non-plastic solutions. The Food and Agriculture Organization (FAO) tries to distinguish between plastic alternatives and plastic substitutes. Plastic alternatives are the materials that serve as a good alternative to plastics, also referred to as “better plastic”, but may still include plastics in their composition to reduce environmental impact by incorporating bio-based or biodegradable components, for example, bio-based plastics derived from renewable resources like sugarcane, corn, or starch (e.g., polylactic acid [PLA], bio-polyethylene). Plastic substitutes are non-plastic materials that completely replace plastic in functionality, focusing on reducing or eliminating the use of synthetic polymers entirely. These substitutes are typically derived from natural or renewable resources; for example, natural materials like paper, cardboard, bamboo, jute, or wood for packaging and product applications.

Non-plastic substitutes, as used in the global plastics treaty Intergovernmental Negotiating Committee (INC) negotiations, are derived from natural, renewable, and plant-based sources, such as biopolymers from jute or seaweed. Because of their polymer characteristics, these should not be referred to as plastic or plastic alternatives. As per the FAO definition, these should not be referred to as better plastic alternatives, as there are no traces of plastics in this biopolymer. For example, biopolymers made from jute in Bangladesh are tested and certified as ‘non-plastic’ biopolymers. However, due to a lack of taxonomy and terminology, the material is often referred to as a better plastic alternative. This semantic imprecision undermines both market differentiation and policy enforcement, blurring the line between genuinely non-plastic solutions and modified polymers.

To address this issue, we propose the development of a harmonised international classification system under the assistance of ISO or UNEP that clearly distinguishes between plastic alternatives (modified plastics) and non-plastic substitutes (entirely polymer-free). This should be supported by mandatory labelling standards and certification schemes that identify whether a material falls within the ZTP category or qualifies as a non-plastic substitute. National governments could further reinforce this distinction through eco-modulated Extended Producer Responsibility schemes and green procurement policies that prioritise verified non-plastic substitutes for industry sectors. These legislative mechanisms would enhance transparency, reduce greenwashing, and create a policy environment more aligned with the material’s accurate environmental profile.

3.2. Emergence of New Terminologies

Addressing these issues requires collaboration across industries and relevant stakeholders and national and international standardisation bodies to establish a unified terminology for materials. Standardisation bodies must define terms like “bioplastic,” “biodegradable,” and “compostable” using rigorous criteria to ensure consistency and accuracy of the terms. Governments and regulatory bodies should enforce appropriate labelling standards to prevent misleading claims, while educational campaigns should enhance public understanding of different materials and their environmental impacts. This collective effort is crucial for navigating the complexities of plastics and polymers.

A promising innovation in the field is the concept of ‘zero-trace plastic’ (ZTP) or ‘non-pollutant plastic’ (NPP). ZTP materials are entirely free of synthetic plastic components in their composition and are designed to exhibit non-polluting characteristics throughout their lifecycle. It is crucial to differentiate between plastic-based and non-plastic materials that perform similar functions, given the versatility of applications traditionally served by plastics. Clarifying the material origin, whether plastic or non-plastic, can help resolve longstanding ambiguities in classification and bring greater precision to material taxonomies. Furthermore, ensuring non-polluting properties is particularly important in light of the environmental challenges posed by synthetic plastics, such as their persistence, slow degradation, and contribution to microplastic pollution.

Unlike biodegradable plastics, which may leave harmful residues, NPPs or ZTPs decompose entirely without leaving pollutants or any form of environmental footprint. Advancements in polymer science are necessary to engineer materials with precise molecular structures capable of complete degradation without producing intermediate pollutants. In recent years, scientists and industries have made a considerable contribution to introducing NPP products manufactured from bio-based sources such as plants, including jute and seaweed.

Examples like polyhydroxyalkanoates (PHAs) demonstrate that such materials are achievable, though challenges remain in scaling production and reducing costs. The potential of NPP offers hope for a more sustainable future, particularly in avoiding microplastic pollution around the world.

Furthermore, biodegradable plastics labelled as compostable present a significant challenge in waste management when they fail to enter appropriate composting facilities. Despite being designed to break down under controlled composting conditions, it is absent in practical terms in most countries [30]. These materials are often excluded from composting streams due to various practical and operational issues [64].

One primary concern is the tendency for compostable plastics to clog equipment at industrial composting facilities [65,66,67,68]. Unlike organic waste, compostable plastics may require specific environmental conditions, high temperatures, humidity, and microbial activity, to degrade effectively. Without these conditions, the material can remain intact, obstruct machinery, and compromise overall facility efficiency [69].

Additionally, there is often a lack of knowledge and understanding among composting facility staff regarding compostable plastics. Proper education and training are required to correctly recognise and process these materials, but this demands time and financial investment from facility operators, which may not be prioritised [70].

Another critical issue is the need for enforcement mechanisms to verify the degradability of compostable plastics in real-world composting settings. While standards such as ASTM D6400 [28] or EN 13432 and EN 14995 [29,71] provide criteria for compostability, facilities often need more resources to confirm whether a given material complies with these standards [72]. This gap highlights the need for a robust traceability system that would allow all stakeholders, from material manufacturers to composting facility operators, to share information about compostable plastics’ composition and degradation behaviour [73]. Such systems would enable facilities to verify degradability reports and ensure that only suitable materials enter the composting process. Without a unified traceability framework and enforcement mechanisms, compostable plastics risk being rejected, ultimately undermining the environmental goals they aim to achieve. As a result, developing compostable materials that fail to enter the composting waste stream raises critical questions about the effectiveness of current systems and the need for better coordination across the value chain.

The performance of bioplastics during degradation is highly variable and largely depends on the environment in which they are disposed of [74]. In industrial composting settings, materials like polylactic acid (PLA) can degrade efficiently [75]. However, this process requires specific conditions such as sustained high temperatures, controlled humidity, and the presence of appropriate microorganisms. PLA remains largely intact without these factors and fails to break down as intended. This creates a gap between its designed performance and real-world behaviour, mainly when industrial composting facilities are unavailable or inaccessible.

In marine environments, the degradation of biodegradable plastics is significantly hindered [76]. The cooler temperatures, lower oxygen levels, and distinct microbial communities found in seawater slow down or even halt decomposition. As a result, many plastics labelled as biodegradable persist for extended periods in marine ecosystems, contributing to long-term pollution and posing a threat to marine life through fragmentation into microplastics. This discrepancy highlights the need to distinguish between laboratory-tested biodegradation claims and actual environmental outcomes, particularly in sensitive ecosystems like oceans.

Soil environments further illustrate the variability in bioplastic degradation [77]. Factors such as moisture levels, temperature fluctuations, oxygen availability, and microbial activity vary widely depending on soil type and geographic location, making the decomposition rates of bioplastics unpredictable. For example, while some materials may break down relatively quickly in moist, aerated soils with high microbial activity, others may persist under drier or oxygen-poor conditions. This variability complicates waste management strategies, as bioplastics that are designed for biodegradation under ideal conditions may fail to achieve complete breakdown in typical soil environments, potentially leaving residues or contributing to microplastic pollution. These inconsistencies in degradation performance highlight the limitations of relying solely on existing compostability certifications and underline the urgent need for new frameworks aligned with real-world disposal environments. In response to these limitations, we propose a performance-based framework that more rigorously links material degradation claims to actual environmental outcomes.

4. The Proposed New Terminologies to Overcome Existing Challenges and Confusions

To address the misalignment between laboratory-tested compostability and field-based environmental performance, we propose a new conceptual benchmark: Zero-Trace Plastic (ZTP). Zero-Trace Plastic (ZTP) can be defined as materials that are non-plastic substitutes intended for versatile plastic-like uses while guaranteeing no trace of synthetic plastics in their composition and no contribution to pollution across their lifecycle.

Ensuring proper management of biodegradable plastics requires significant engagement from national standardisation bodies to establish transparent certification schemes that account for geographic and environmental conditions. The differentiation of plastic alternatives labelled or certified as biodegradable must reflect the environments in which they can fully or partially degrade, preventing misleading claims and mismanagement. To address this challenge, environment-specific designations such as marine-ZTP (Zero-Trace Plastic), soil-ZTP, or mandatory ZTP management for industrial composting could introduce a standardised framework for assessing the degradability of materials under real-world conditions.

The degradability labels would provide much-needed transparency and practical understanding by associating a material’s degradation capability with the environment in which it is expected to break down fully without leaving harmful residues. For example, a marine-ZTP certification would indicate that a plastic alternative can completely degrade marine conditions, including exposure to colder temperatures and lower microbial activity, without producing microplastics or releasing toxic chemicals. Similarly, a soil-ZTP designation would certify that a material can biodegrade in natural soil environments, taking into account variable moisture, oxygen levels, and microbial presence. Additionally, a mandatory ZTP certification for industrial composting would specify that a material requires controlled high-temperature composting to ensure complete breakdown, preventing the misplacement of such materials in home composting or landfill systems.

National standardisation bodies play a critical role in developing and implementing these designations, ensuring that biodegradable plastics are appropriately certified according to the required degradation conditions. By establishing these clear, environment-specific categories, policymakers and industry stakeholders can improve waste stream efficiency, enhance consumer awareness, and prevent contamination of composting and recycling systems.

This categorisation would address the ambiguity around biodegradability claims, providing stakeholders with clear guidelines on where these materials can be safely disposed of and managed. Waste management systems would benefit from this clarity, ensuring that composting facilities, soil applications, or marine ecosystems are not burdened with materials that fail to meet their specific degradation requirements. At the same time, consumers would better understand how to dispose of biodegradable plastics appropriately, aligning the material’s design with its real-world environmental performance.

The ZTP would not only confirm the absence of plastic traces in the new and emerging plastic substitute options but also foster avoidance of plastic pollution. Thus, the terminology of ZTP as a “non-pollutant plastic” (NPP) has far-reaching implications for research, policy, business, society, and the environment. Scientists would need to innovate bio-inspired polymers and enzymatic degradation mechanisms, while governments could integrate this concept into waste management strategies. Transparent labelling and certification systems would help ensure credibility and foster consumer trust. Education and outreach initiatives are essential for promoting understanding and encouraging the adoption of these materials, contributing to a cultural shift toward sustainable consumption.

Economic considerations are critical in the transition to non-pollutant plastic (NPP) or zero-trace plastic (ZTP). Developing and scaling these materials requires significant investment in research and infrastructure. However, the growing market demand for sustainable solutions presents opportunities for companies to lead in innovation and gain competitive advantages. Collaboration between governments and the private sector is necessary to fund advancements and recognise the long-term environmental and economic benefits of reducing plastic pollution.

5. Proposed Validation and Certification Procedure

The ZTP, as shown in Figure 2, certification assesses whether a plastic material, such as polylactic acid (PLA), leaves no harmful, persistent, or inorganic residues throughout its degradation in natural or managed environments. This certification focuses on the material level and applies only when the plastic demonstrably decomposes completely and benignly by internationally recognised standards. The certification procedure unfolds sequentially, beginning with a comprehensive biodegradability assessment and proceeding to pollutant trace analysis only if the material successfully meets the biodegradability criteria.

The first step in the ZTP certification is to evaluate the plastic’s biodegradability under multiple environmental conditions. The material must be tested by ISO 14855-1 or ISO 17088 for industrial composting, ISO 19679 and ISO 18830 for marine environments, and ISO 22404, ISO 17556, or ASTM D5988 for soil biodegradation [78,79,80,81,82,83,84]. In each test scenario, the material must demonstrate a minimum of 90% biodegradation within the time frame defined by the relevant standard, with biodegradation measured in terms of CO₂ evolution or CH₄ generation. The degradation must proceed without leaving visible fragments, microplastics, or any detectable polymer residues in the residual matrix. If the plastic fails to achieve complete biodegradability in any of these environmental settings, it is disqualified from Zero Trace Plastic certification.

Only after the material has passed all required biodegradability tests does it proceed to the stage of assessing trace pollutants. In this phase, the plastic sample is subjected to trace residue analysis to verify the absence of persistent inorganic and synthetic organic pollutants. Inorganic trace elements are evaluated using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The plastic sample must be fully digested using nitric acid, potentially in combination with hydrogen peroxide or microwave-assisted protocols, to ensure complete dissolution of residual metals. The ICP-MS scan must include, at minimum, tin (Sn), zinc (Zn), aluminium (Al), titanium (Ti), chromium (Cr), lead (Pb), cadmium (Cd), and antimony (Sb). To meet ZTP certification requirements, none of these elements may be detected above a concentration of one part per million (ppm).

If a non-metal–organic catalyst was used in the production process, such as a guanidine derivative, then a targeted organic residue analysis must also be conducted using gas chromatography–mass spectrometry (GC-MS) or liquid chromatography–mass spectrometry (LC-MS), depending on the expected molecular characteristics. The sample must be extracted using an appropriate solvent and screened for the parent catalyst compound, any degradation intermediates, and non-biodegradable byproducts. No synthetic organic residues above 1 ppm are permitted. Only organics that are fully biodegradable and originate from renewable resources are acceptable.

Finally, the material’s full formulation must be disclosed. The producer must submit a bill of substances used in the polymerisation process, including monomer origin, catalysts, stabilisers, plasticisers, and any additional processing aids. The certification panel evaluates whether the ingredients used are consistent with the zero-trace philosophy. Additives such as halogenated compounds, phthalates, per- and polyfluoroalkyl substances (PFAS), or persistent antioxidants are not permitted under the ZTP certification criteria, even if they are not detectable in the final product, as they introduce a potential for residual risk.

Suppose the material passes all required tests, biodegradability in multiple environments, absence of inorganic and persistent organic pollutants, and complete transparency of bio-based inputs. In that case, it is awarded Zero Trace Plastic certification. If any test fails, certification is denied. The ZTP certification thus offers a rigorous, tiered methodology to ensure that a plastic product leaves no harmful trace in the environment and complies with the strictest standards of ecological material neutrality. To ensure alignment with international standards, ZTP adheres to ISO and ASTM-defined biodegradation thresholds (proposition for 90% mineralisation under test conditions within 6–12 months), while extending them by requiring trace-pollutant analysis and environment-specific designation (soil-ZTP, marine-ZTP). These designations reflect real-world conditions such as industrial composting systems, terrestrial environments with variable oxygen and microbial levels, or marine ecosystems with low temperature and salinity. ZTP thus complements existing standards (for example, ASTM D6400, EN 13432) by integrating contextual performance expectations and pollutant residue screening, providing a more comprehensive framework for sustainable material certification.

6. Conclusions

In this communication brief, the authors outlined an important challenge, particularly distinguishing between the plastic substitutes (nature-based non-plastic materials) and plastic alternatives (better plastics in terms of biodegradability and compostability, but still plastic traces are available) to avoid existing ambiguity. Thus, clarifying the terminology surrounding plastics, bioplastics, and biopolymers is not merely a semantic exercise; it is foundational for effective policy, consumer transparency, and sustainable material innovation. As demonstrated throughout this paper, existing classifications frequently conflate distinct concepts, including bio-based sourcing, polymer structure, and environmental degradability, resulting in widespread confusion and misaligned expectations across both markets and waste management systems.

This concept offers a corrective to that confusion through a structured classification matrix and the introduction of the notion of Zero-Trace Plastic, a forward-looking policy proposition that links material design to real-world degradation outcomes. Unlike current certifications, ZTP calls for environment-specific performance thresholds and system-wide traceability, ensuring that materials labelled as “sustainable” genuinely align with ecological safety across marine, soil, and composting contexts.

To clarify, the ZTP framework is not proposed as a replacement for existing standards such as ASTM D6400 or EN 13432, but as a complementary benchmark that strengthens them by integrating environmental specificity and traceability. ZTP highlights a performance-based distinction that can guide both innovation and governance, particularly where current biodegradability or compostability claims lack clarity or practical enforcement mechanisms.

For policymakers, the implications are clear. Harmonised international standards, under bodies such as ISO, UNEP, and regional regulatory authorities, are urgently needed to anchor the next generation of plastics in scientific rigour and ecological relevance. ZTP can serve as a conceptual foundation for these efforts, informing labelling reforms, product bans or incentives, procurement criteria, and eco-modulated Extended Producer Responsibility schemes.

Beyond regulatory pathways, ZTP initiates a new research and innovation agenda centred on the development of non-pollutant materials that fully degrade in real-world conditions, without residual toxicity or microplastic formation. This includes the need to define robust testing protocols, ecotoxicological thresholds, and validation mechanisms aligned with geographic and infrastructure realities. Given its rigorous environmental benchmarks and traceability requirements, the ZTP framework holds strong potential for adoption by regulatory and standardisation bodies such as ISO, UNEP, and national environmental agencies. It could guide eco-modulated Extended Producer Responsibility schemes and serve as a procurement criterion for sustainable materials in the public and private sectors.

Going forward, we recommend pilot testing of ZTP-aligned materials, developing environment-specific biodegradation benchmarks, and a labelling architecture that integrates both origin (bio-based) and end-of-life performance (trace-free breakdown). Further engagement with composting operators, marine pollution specialists, and product designers will be crucial to translate the ZTP principles into measurable certification pathways. Doing so would not only reduce consumer confusion and greenwashing but also strengthen regulatory coherence, improve market transparency, and support innovation incentives. These outcomes collectively accelerate the shift toward a genuinely circular, low-toxicity plastics economy by aligning environmental claims with verifiable performance, enhancing consumer trust, and enabling more efficient investment in sustainable materials. While the term Zero-Trace Plastic is used throughout this paper for technical consistency, the concept can also be referred to in public discourse as “non-pollutant plastic (NPP)” due to its communicative simplicity and emphasis on environmental safety. Future empirical studies should prioritise real-world pilot testing of ZTP-certified materials, evaluating degradation kinetics and pollutant traceability under diverse environmental conditions to support eventual standardisation.