Biodegradable plastic product testing

Understanding Biodegradable Plastics

Biodegradable plastics represent a significant advancement in addressing global plastic pollution. Unlike conventional plastics that persist in the environment for hundreds of years, biodegradable plastics are engineered to break down through biological processes—microbial activity, enzymatic action, or composting—reducing persistent environmental accumulation.

Categories of Biodegradable Plastics

Understanding the distinctions between different types of biodegradable plastics is critical for manufacturers, regulators, and consumers:

Bio-based and Biodegradable

• Derived from renewable resources such as corn starch, sugarcane, or cassava

• Fully biodegradable under appropriate conditions

• Examples: PLA (polylactic acid), PHA (polyhydroxyalkanoates), PHB (polyhydroxybutyrate)

• Maximum sustainability achieved when both bio-based and biodegradable

Fossil-based and Biodegradable

• Synthesized from petroleum feedstocks but chemically designed to biodegrade

• Examples: PBAT (polybutylene adipate terephthalate), PCL (polycaprolactone)

• Offer biodegradability without requiring bio-based feedstocks
  
  

Oxo-degradable Plastics

• Conventional plastics with pro-oxidant additives

• Fragment into microplastics rather than fully biodegrading

• Not considered genuinely biodegradable under most regulatory frameworks

• Subject to increasing regulatory restrictions

Important Note: Not all bio-based plastics are biodegradable, and not all biodegradable plastics are bio-based. Consumer claims, marketing communications, and regulatory compliance all hinge on verified biodegradability rather than assumed degradability.

Why Biodegradable Plastic Testing Matters

The Problem with Unverified Claims

The term "biodegradable" is often misunderstood or misused in marketing. Without proper testing, products may claim biodegradability without actually breaking down in realistic environmental conditions. This "greenwashing" undermines consumer trust and can result in:

• Environmental harm from materials that persist longer than claimed

• Regulatory non-compliance and potential penalties

• Reputational damage when products fail to perform as advertised

• Missed opportunities for genuine environmental improvement

Benefits of Proper Testing

For Manufacturers and Retailers:

• Assurance that products meet quality, safety, and environmental standards

• Increased buyer confidence and product sales

• Access to markets requiring certified biodegradable products

• Protection against liability and reputational risks

For Buyers and Consumers:

• Confidence that environmental claims are substantiated

• Support in selecting genuinely sustainable products

• Assurance that products meet strict environmental criteria

For the Environment:

• Reduced plastic pollution and persistence

• Protection of soil, water, and ecosystem health

• Support for circular economy initiatives

Key Testing Standards for Biodegradable Plastics

International Standards Framework

Multiple organizations have defined standards and requirements for testing biodegradable plastics:

European Standards:

• EN 13432: Industrial compostability for packaging

• EN 14995: Industrial compostability for plastic materials other than packaging

• ISO 17088: International equivalent to EN 13432

• ISO 14855: Aerobic biodegradability under controlled composting conditions

American Standards:

• ASTM D6400: Specification for compostable plastics

• ASTM D5338: Aerobic biodegradation under controlled composting

• ASTM D5526: Anaerobic biodegradation under landfill conditions

Other Regional Standards:

• AS 5810: Home compostability (Australia)

• NF T51-800: Home compostability (France)

• ISO 17556: Biodegradability in soil

• ISO 23977: Biodegradability in marine environments

ASTM D6400: The Primary Compostability Standard

ASTM D6400 is the primary standard for labeling plastics as compostable in the United States. It specifies requirements for plastics and products designed to be composted in municipal and industrial aerobic composting facilities.

Testing Requirements:

1. Inherent Biodegradability

   • CO₂ evolution must reach ≥60% of theoretical maximum within 180 days

   • Testing conducted under controlled composting conditions (58 ± 2°C)

   • Based on ISO 14855 methodology

2. Disintegration

   • No more than 10% of original dry mass remaining after 12 weeks

   • Material must pass through a 2mm sieve

   • No visible film fragments remaining

3. Ecotoxicity

   • Compost quality must not be adversely affected

   • Plant growth tests using mature compost

   • Germination rates and biomass compared to controls

4. Heavy Metal Content

   • Strict limits on lead, cadmium, chromium, mercury, and other heavy metals

   • Prevents soil contamination from compostable products

EN 13432: European Industrial Compostability Standard

EN 13432 is the harmonized European standard for determining whether packaging materials can be classified as industrially compostable. To comply with EN 13432:2000, packaging must meet minimum requirements for four characteristics:

1. Characterization of Constituents

• Material must contain at least 50% volatile solids

• Must not contain heavy metals or other toxic chemicals in concentrations that may harm the environment

2. Biodegradation

• At least 90% of the material must biodegrade within 6 months in aerobic conditions

• Temperature generally set at 58 ± 2°C per ISO 14855 standard

3. Disintegration

• After 12 weeks of aerobic composting, at least 90% of test material (by dry weight) must pass through a 2mm sieve

4. Ecotoxicity and Compost Quality

• Resulting compost must not have detrimental effect on plant growth

• Comparison with blank compost controls

Regulatory Update: The current EN 13432 standard from 2000 is due to be updated to ensure composting times and acceptable contamination levels better reflect actual conditions in biowaste treatment facilities. The new EU Packaging and Packaging Waste Regulation (PPWR) requires certain compostable packaging to comply with harmonized standards by February 12, 2028.

ASTM D5338: Aerobic Biodegradation Testing

ASTM D5338 (equivalent to ISO 14855) provides test methods for determining the degree and rate of aerobic biodegradation of plastics in controlled composting environments under laboratory conditions.

Key Parameters:

• Temperature: 58 ± 2°C

• Duration: Up to 180 days for full assessment

• Measurement: CO₂ evolution indicating carbon conversion

• Reference material: Microcrystalline cellulose

Applications:

• R&D biodegradability screening before full compostability assessment

• Material formulation comparison during product development

• Quality control for biodegradable plastic production

ASTM D5526: Anaerobic Biodegradation Testing

Evaluates biodegradation under accelerated landfill conditions—relevant for plastics that may end up in managed landfills rather than composting facilities.

Key Parameters:

• Simulates anaerobic digestion environment

• Measures CO₂ and CH₄ production

• Assesses biodegradation in waste management scenarios

Testing Environments and Conditions

Industrial Composting

Conditions:

• High temperature (58 ± 2°C)

• Controlled humidity and aeration

• Professional biowaste treatment facilities

• Typical duration: 12 weeks for disintegration, 6 months for biodegradation

Applicable Standards:

• EN 13432 (Europe)

• ASTM D6400 (USA)

• ISO 17088 (International)

• EN 14995 (Non-packaging plastics)

Home Composting

Conditions:

• Ambient temperature (25 ± 5°C)

• Variable humidity and conditions

• Lower and more variable temperatures than industrial facilities

• Longer timeframes required

Applicable Standards:

• AS 5810 (Australia)

• NF T51-800 (France)

• New EN standard under development (expected 2026)

Home Compostability Requirements (AS 5810):

• Biodegradation: At least 90% w/w within 12 months at 25 ± 5°C

• Disintegration: At least 90% w/w through 2mm sieve after 180 days

• Remaining material not distinguishable from compost at 500mm distance

• Compost must not negatively impact plant growth or worm survival

Soil Biodegradation

Conditions:

• Natural soil environment

• Ambient temperature

• Relevant for agricultural and horticultural applications

Applicable Standards:

• ISO 17556: Aerobic biodegradability in soil

• ISO 23517: Biodegradability in soil for mulch films and agricultural materials

Applications:

• Agricultural mulch films

• Horticultural products

• Forestry applications

• Landscaping materials

Marine Environment Biodegradation

Conditions:

• Seawater environment

• Lower temperatures and different microbial communities

• Relevant for fishing gear and marine-exposed products

Applicable Standards:

• ASTM D6691: Aerobic biodegradability in seawater

• ISO 23977: Biodegradability in seawater

• ISO 19679: Marine sediment biodegradation

• ISO 23832: Disintegration in marine environment

Testing Approaches:

• Simulated marine conditions in laboratory

• Real marine environment testing using in-house methods

Anaerobic Digestion

Conditions:

• Oxygen-free environment

• Relevant for biogas production facilities

• Important for waste management scenarios

Applicable Standards:

• ASTM D5526: Anaerobic biodegradation

• ISO 15985: Anaerobic digestion conditions

The Testing Process

Phase 1: Sample Preparation

Pre-testing Requirements:

• Material characterization and documentation

• Sample homogenization and preparation

• Moisture content determination

• Particle size reduction for testing consistency

Best Practices:

• Convert plastics into thin films for consistent testing

• Use cryogenic milling for fragmentation

• Ensure uniform sample size and composition

• Document material formulation and additives

Phase 2: Biodegradation Testing

Aerobic Biodegradation:

• Material exposed to specific biodegradation conditions

• Inoculum from relevant environment (compost, soil, seawater)

• CO₂ evolution measured over time

• Comparison with reference materials (microcrystalline cellulose)

Anaerobic Biodegradation:

• Material exposed to anaerobic conditions

• CO₂ and CH₄ production measured

• Relevant for landfill and biogas scenarios

Duration:

• Industrial composting: 6 months

• Home composting: 12 months

• Soil biodegradation: Typically up to 2 years

• Marine biodegradation: Varies by standard

Phase 3: Disintegration Testing

Physical Assessment:

• Material subjected to composting conditions

• Sieving through 2mm screen after specified duration

• Mass loss determination

• Visual inspection for fragments

Criteria:

• Maximum 10% retained on 2mm sieve

• No visible film fragments

• Complete integration with compost matrix

Phase 4: Ecotoxicity Testing

Purpose: Ensure biodegradation products do not harm the environment

Testing Methods:

Aquatic Toxicity:

• OECD 201: Growth inhibition of freshwater microalgae and cyanobacteria

• OECD 202: Acute immobilization of Daphnia magna

• ErC50 and NOEC determination

Terrestrial Toxicity:

• OECD 207: Acute toxicity to earthworms (Eisenia foetida)

• OECD 208: Seedling emergence and early growth inhibition in higher plants

• Germination rate and biomass comparison

Compost Quality:

• Plant growth tests using mature compost

• Germination rates compared to blank controls

• No significant inhibition required

Important Considerations:

• High concentrations of biodegradable material can cause transient "toxic" effects due to oxygen depletion

• Reference control using GRAS (Generally Recognized As Safe) materials like microcrystalline cellulose

• Comparison with biodegraded reference material accounts for soil disturbance effects

Phase 5: Chemical Testing

Heavy Metal Analysis:

• Lead (Pb), Cadmium (Cd), Chromium (Cr), Mercury (Hg)

• Zinc (Zn), Copper (Cu), Nickel (Ni)

• Strict limits per applicable standards

Volatile Solids:

• Minimum 50% volatile solids content

• Indicates organic material availability for biodegradation

Other Contaminants:

• Fluorine content

• Other regulated substances per regional requirements

Biodegradation Mechanisms and Science

Surface Erosion Process

Biodegradable plastics are typically water-insoluble solid materials under normal environmental conditions. Biodegradation occurs as a surface erosion process at the solid/liquid interface:

Step 1: Depolymerization

• Extracellular enzymes in the liquid phase

• Break down polymer chains at the material surface

• Release of monomers and oligomers

Step 2: Assimilation

• Monomers assimilated by surrounding microorganisms

• Immediate uptake expected

• Mineralization to CO₂, H₂O, and biomass

Rate-Limiting Factor: Depolymerization is the limiting factor in biodegradation rate. Surface area and particle size significantly affect biodegradation speed.

The Biodegradation Percentage Paradox

A critical insight for testing interpretation: biodegradation percentage does not fully represent material fate.

Example Scenario:

• 1g plastic cube with isotropic biodegradable polymer

• Constant erosion rate: 0.0095 cm day⁻¹ cm⁻²

• After 16 days: 39% nominal biodegradation

• Remaining cube: 0% biodegraded

• Missing mass: 100% biodegraded

Implications for Testing:

• Biodegradation percentage is a ratio, not an absolute measure

• Number of macromolecules metabolized matters for ecotoxicity assessment

• Higher initial mass provides more material for potential toxic by-product formation

• Test design should maximize metabolized mass for robust ecotoxicity assessment

Certification and Labeling

DIN CERTCO Compostable Mark ("Seedling")

The internationally recognized Compostable Mark, developed by DIN CERTCO and European Bioplastics e.V., indicates certified compostability.

Certification Requirements:

• Testing by DIN CERTCO-recognized third-party laboratories

• Compliance with EN 13432 or equivalent standards

• All individual components must meet requirements

• Regular surveillance and re-certification

Benefits:

• Consumer recognition and trust

• Market access in regions requiring certification

• Differentiation from non-certified products

• Support for proper disposal through biowaste collection

Other Certification Programs

OK Compost (TÜV Austria):

• Industrial compostability certification

• Home compostability certification (OK Compost HOME)

• International recognition

BPI Certification (USA):

• Biodegradable Products Institute certification

• Based on ASTM D6400

• North American market focus

Labeling Requirements

Essential Elements:

• Clear indication of compostability claim

• Specification of composting environment (industrial vs. home)

• Statement whether claim applies to product or packaging

• Recognition by consumers for proper disposal

EU PPWR Requirements: By February 12, 2028, certain compostable packaging must comply with harmonized standards. Labels must clearly indicate:

• Industrial compostability vs. home compostability

• Proper disposal pathway

• Product vs. packaging claim

Testing Challenges and Considerations

Condition Specificity

Challenge: A plastic certified as industrially compostable may not biodegrade in home composting, soil, or marine environments.

Solution:

• Test under conditions matching intended end-of-life environment

• Conduct multiple tests for products with various disposal pathways

• Clear labeling of appropriate disposal method

Additive Interference

Challenge: Plasticizers, pigments, and processing aids may affect biodegradation rates or introduce ecotoxic compounds not present in the base polymer.

Solution:

• Test final product formulation, not just base polymer

• Document all additives and their concentrations

• Assess additive impact on biodegradation and ecotoxicity

Fragmentation vs. Mineralization

Challenge: Physical breakdown into smaller pieces is not equivalent to biodegradation. True biodegradation requires mineralization—conversion of organic carbon to CO₂, water, and biomass.

Solution:

• Measure CO₂ evolution, not just mass loss

• Ensure complete mineralization, not just fragmentation

• Distinguish between biodegradable and oxo-degradable plastics

Material Heterogeneity

Challenge: Multi-layer or composite materials may have different biodegradation rates for different components.

Solution:

• Test each layer separately

• Ensure all components meet biodegradability requirements

• Consider isotropic materials for simpler testing

Test Duration

Challenge: Long test durations (6-12 months) delay product development and market entry.

Solution:

• Use high surface area samples to increase biodegradation rate

• Optimize particle size through milling

• Conduct R&D screening tests before full certification testing

• Partner with laboratories offering accelerated testing approaches

Selecting a Testing Laboratory

Accreditation Requirements

ISO/IEC 17025:2017 Certification:

• International standard for testing and calibration laboratories

• Ensures competence, impartiality, and consistent operation

• Required for regulatory compliance testing

• Specific testing standards must be on scope of accreditation

Key Selection Criteria

1. Accreditation Scope

• Verify specific biodegradability testing standards are accredited

• Check recognition by certification bodies (DIN CERTCO, BPI)

• Confirm experience with relevant environmental conditions

2. Technical Expertise

• Experience in biodegradability testing

• Knowledge of applicable standards and regulations

• Understanding of polymer science and biodegradation mechanisms

3. Laboratory Capabilities

• Multiple testing environments (compost, soil, marine, anaerobic)

• Comprehensive testing (biodegradation, disintegration, ecotoxicity, chemical)

• Modern instrumentation and facilities

4. Customer Support

• Clear communication throughout testing process

• Real-time data progression updates

• Interim results during testing

• Consultation on test selection and interpretation

5. Turnaround Time

• Competitive testing durations

• Clear timelines and scheduling

• Expedited options for urgent projects

Applications of Biodegradable Plastics

Packaging

• Shopping bags and garbage bags

• Food packaging and containers

• Protective packaging materials

• Compostable films and wraps

Disposable Products

• Cutlery and food service items

• Disposable tableware

• Single-use applications

• Food contact articles

Agricultural Applications

• Mulch films

• Planting pots and containers

• Agricultural films

• Horticultural products

Consumer Products

• Personal care items

• Cosmetics packaging

• Household products

• Toys and leisure items

Future Trends in Biodegradable Plastics Testing

Harmonized Home Compostability Standard

The EU Commission will request European standardization organizations by February 12, 2026, to create harmonized home compostability standards. This will:

• Provide unified criteria for home compostability claims

• Replace current use of AS 5810 and NF T51-800

• Align with PPWR requirements

Updated Industrial Compostability Standards

EN 13432 and related standards are being updated to:

• Better reflect actual composting facility conditions

• Address realistic timeframes and contamination levels

• Improve alignment with biowaste treatment processes

Marine Biodegradability Focus

Increasing attention on:

• Standards for marine environment degradation

• Testing for fishing gear and marine applications

• Prevention of ocean plastic pollution

Digital Documentation

Evolution toward:

• Electronic certificates and documentation

• Blockchain for supply chain traceability

• Real-time testing data access

Conclusion

Biodegradable plastic product testing is essential for verifying genuine environmental claims and ensuring materials perform as intended in realistic disposal environments. From industrial composting to home composting, soil to marine environments, proper testing demonstrates that materials break down safely without harming ecosystems.

The distinction between bio-based and biodegradable plastics, between fragmentation and mineralization, and between different environmental conditions requires rigorous testing to substantiate marketing claims. Standards such as ASTM D6400, ASTM D5338, EN 13432, and ISO 17088 provide the scientific framework to distinguish true biodegradability from misleading claims.

For manufacturers, testing offers market access, consumer confidence, and regulatory compliance. For consumers, it provides assurance that environmental claims are genuine. For the environment, it ensures that biodegradable plastics deliver real environmental benefits rather than unintended consequences.

As regulatory requirements evolve under the EU Packaging and Packaging Waste Regulation and other frameworks, biodegradability testing becomes increasingly critical for market access. Partnering with ISO/IEC 17025 accredited laboratories ensures reliable results, expert guidance, and support throughout the testing and certification process.

The future of plastics lies in sustainable solutions, and rigorous biodegradable plastic testing is the foundation for building trust, enabling innovation, and delivering genuine environmental value.

Frequently Asked Questions

Q1: What is the difference between biodegradable and compostable plastics?

Biodegradable plastics break down through microbial activity in various environments. Compostable plastics are a subset of biodegradable plastics that meet specific standards for degradation in composting conditions within defined timeframes, producing non-toxic compost suitable for soil amendment.

Q2: How long does biodegradable plastic testing take?

Industrial compostability testing typically takes 6-12 months. Home compostability testing may take up to 12 months. Soil and marine biodegradation tests can take 1-2 years. R&D screening tests may be shorter (3-6 months).

Q3: Can a product be labeled "biodegradable" without certification?

While technically possible, unverified biodegradability claims risk regulatory action, reputational damage, and consumer distrust. Certification by recognized bodies provides third-party verification essential for market credibility.

Q4: Do biodegradable plastics decompose in landfills?

Most biodegradable plastics require specific conditions (oxygen, temperature, moisture) not typically found in landfills. Anaerobic biodegradation tests (ASTM D5526) assess performance in landfill conditions, but industrial composting is generally the intended disposal pathway.

Q5: What is the difference between ASTM D6400 and EN 13432?

ASTM D6400 is the primary US standard for compostable plastics; EN 13432 is the European equivalent. Both require biodegradation, disintegration, and ecotoxicity testing with similar criteria. Key differences include specific test methods and heavy metal limits.

Q6: Are bio-based plastics always biodegradable?

No. Bio-based plastics derived from renewable resources may or may not be biodegradable. For example, bio-PET (from sugarcane) is chemically identical to petroleum-based PET and is not biodegradable. Biodegradability depends on chemical structure, not feedstock source.

Q7: Can biodegradable plastics be recycled with conventional plastics?

Generally, no. Biodegradable plastics can contaminate conventional plastic recycling streams and reduce recycled material quality. Proper labeling and consumer education are essential to keep biodegradable plastics out of recycling streams.

Q8: What happens if biodegradable plastic ends up in the ocean?

Materials designed for industrial composting may not degrade in marine environments. Specific marine biodegradability testing (ASTM D6691, ISO 23977) is required for applications where ocean exposure is possible, such as fishing gear.

Q9: How should I prepare samples for biodegradability testing?

Samples should be converted to thin films or small particles through cryogenic milling to maximize surface area. Document all additives, plasticizers, and processing aids. Test final product formulation, not just base polymer.

Q10: What is the Seedling mark?

The Seedling mark is the DIN CERTCO Compostable certification mark indicating products have been tested and certified to meet EN 13432 or equivalent compostability standards. It is recognized internationally and helps consumers identify genuinely compostable products.