Bioplastic Glossary

The Rise of Plastic Alternatives

Fossil-fuel based single-use plastic can take hundreds to thousands of years to breakdown, and is the main source of plastic pollution affecting our ocean. In recent years, new materials collectively called “bioplastics” have entered the market. These products are advertised as a sustainable alternative to plastic, and often labeled as biodegradable or compostable.

There is a lot of confusion and mixed results as to what is considered a bioplastic, whether those labeled as compostable or biodegradable actually break down in the natural environment, and whether the feedstocks used to make bio-based plastics are environmentally preferred to fossil fuels. Therefore, its not always the case that bioplastics be considered a sustainable alternative to plastic. The Surfrider Foundation advocates for source reduction of single-use plastics, and encourages the adoption of reusable items as the best way to move away from single-use plastic. Furthermore, Surfrider does not advocate for the use of bioplastic materials as the preferred alternative to conventional plastics. This is because most bioplastic materials do not break down in the marine environment, shift the burden to other resources, and perpetuate the single-use mentality. Surfrider has compiled this comprehensive document to help consumers, businesses, and the general public make informed choices as they try to live an ocean friendly lifestyle.

The Problem with Bioplastics

The term bioplastic has been used to describe both fossil-fuel based plastics that are engineered to breakdown quicker in various environments, and bio-based plastics that are developed using biologically-derived feedstocks instead of fossil fuel derivatives. For the purpose of this article, we will be specific and refer to either bio-based plastics (those made from renewable feedstocks) or conventional plastics with enhanced degradation (fossil-fuel based plastics designed to degrade in the environment). To note, not all bio-based plastics are designed to degrade completely or quickly in the natural environment. As such, bio-based materials can be cataloged into fast, medium and slow degraders, based on how much mass they lose after 90 days of home composting. According to the European Commission of Science for Environmental Policy, the fast degraders are predominately made from high levels of starch, the medium degraders are based on wood or coconut fibers, and the slow degraders tend to be composed of polylactic acid (PLA).

While bio-based plastics (like PLA) and conventional plastics with enhanced degradation are commonly touted as sustainable alternatives to conventional plastics, these products will often only breakdown and meet compostable requirements when sent to an industrial composting facility, where there is carefully controlled humidity and temperature. According to findacomposter.com, there are only about 50 of these facilities that accept compostable plastics, nationwide. Even those industrial composters that currently accept bio-based plastics are considering moving away from this practice, as many bio-based plastics fail to meet compostability standards in a useful time period and have even contaminated the larger compost pile by leaching chemicals and other additives, destroying an important economic resource for the compost facility. In other words, PLA plastic will not break down into natural elements (“biodegrade”) in your backyard composting pile, the landfill, or most importantly, the ocean. In addition, if added to the recycling bin, PLA plastics can contaminate recycling processes because they can be chemically different from traditional plastics. The glossary below gives definitions and standards for the common words used to describe single-use disposable items.

Glossary of Bioplastic Terms

There is a lot of confusion about the definitions of terms like biodegradability and compostability. It turns out these definitions can be more complicated than they seem - so we did some digging, hit the literature, and identified the following definitions as the most generally accepted. Findings indicate that the best method of pollution prevention continues to be avoiding single-use packaging all together.

Degradable

Degradable means that a material’s polymers are able to be partially or completely physically altered from environmental factors including light (photodegradation), heat (thermal degradation), chemical (including oxidation), moisture, and/or biological; causing the material to lose properties. This term has no associated timeline, level of breakdown, or avoidance of toxic residues. Therefore, products labeled as just degradable do not provide an effective level of plastic pollution prevention.

Biodegradable

The term “biodegradable” is used to describe plastics and materials able to degrade and break down into their individual molecules and biomass through the use of living organisms (mainly microorganisms like bacteria, fungi, algae or their enzymes). Some definitions include the term “partial” breakdown, as opposed to complete breakdown into molecules and biomass, so there is also the term “complete biodegradation”. Essentially, the term biodegradable is meaningless unless it is accompanied by a percent degradation under a specified timeframe and assurance that no toxic residue will remain. To note, even 90% biodegradation could result in the formation of thousands of microplastics, which is not something that any current standards consider in their testing protocols or criteria.

Compostable

A great definition for compostable is: “materials which biodegrade in a composting process through the action of naturally occurring microorganisms and do so to a high extent within a specified timeframe. The associated biological processes during composting will yield C02, water, inorganic compounds and biomass which leaves no visible contaminants or toxic residue/substances.” This term is regulated by multiple standards, including EN Standard 13432, ASTM D6400, & ASTM 6868. Often times, products labeled as compostable can only meet these criteria in an industrial composting facility. However even products that meet compostabilty requirements do not always meet these requirements in practice. There's been a recent movement to remove even certified compostable bio-based, fossil-fuel based and mixed materials from the few industrial composting facilities that accept them.

Home Compostable

Home compostable means that materials are able to meet the “compostable” specifications without the need for an industrial composting facility. Under TUV Austria's OK Compost HOME certification, the material must (1) biodegrade by 90 percent or more within 365 days (2) fully disintegrate in a way that makes the materials indistinguishable from the compost soil and (3) not have measurable ecotoxicity; through backyard compost methods such as worm bins or compost piles. Home composting for natural food waste like fruits and vegetables, plant debris, and even paper products with minimal ink or chemical processing has some fantastic benefits.

Marine Degradable

Marine Degradable generally means a material has the ability to completely biodegrade under marine environmental conditions including aerobic marine waters or anaerobic marine sediments within a specified timeframe, leaving no toxic substances or residue (doesn’t have any ecotoxicity). Some will only apply this term to non-plastics, such as cellulose materials like paper. A standard providing more clarity, assurance, and testing requirements needs to be provided for this term to be effective and meaningful. On April 1, 2019, TUV Austria released the OK biodegradable MARINE standard which requires that a material is 90 percent degraded (in total or of maximum degradation of a suitable reference substance) within six months, meet specific disintegration requirements, and not have high levels of ecotoxicity.

Oxo-biodegradable

Oxo-biodegradable means that the plastic (generally a conventional fossil-fuel based polymer) has an additive that speeds up the degradation process (a pro-oxidant), causing the plastic to break down into smaller particles, especially when exposed to heat or light. There is no explicit time-frame associated with this term, and no assurance that the smaller particles will completely biodegrade in a timely manner. In the meantime, these micro or nano-sized plastics become even more bioavailable to wildlife. Oxo-biodegradable products cannot be composted, and they negatively impact the recycling stream by reducing the structural integrity of the final product. Therefore, products labeled as oxo-biodegradable do not provide an effective level of plastic pollution prevention.

Synthetic Polymers

Synthetic polymers simply mean “made by chemical synthesis” or “man-made”, and can be derived from petroleum/fossil fuels or bio-based materials (like corn), and once processed, can have the same properties, including lack of ability to degrade, regardless of raw material. Synthetic plastics frequently contain toxic additives to make them have preferred qualities like being malleable, water resistant, heat resistant, and more. There are no assurances that synthetic polymers can completely biodegrade within a specific timeline, meet compostable standards, or be "marine degradable".

Bioplastics

The term “bioplastics” is used to describe both fossil fuel-derived plastics that are biodegradable (they break down to some level at some point in time- could even be thousands of years out), and biomass or renewable resource-derived plastics (termed bio-based plastics). See venn diagram below. Fossil fuel-based plastics that are supposedly biodegradable include PBS (polybutylene succinate) and PCL (polycaprolactone), because they can be “degraded with enzymes and microorganisms”; however, studies do not provide timelines for this to occur, or clarification that treated bioplastics (those containing common additives) are able to completely biodegrade within a specified timeline. Since bioplastics can include fossil-fuel based plastics, products labeled simply as bioplastic do not provide an effective level of plastic pollution prevention.

Bio-derived Plastics

Bio-derived (or bio-based) plastics are plastics derived from biomass or renewable sources, instead of fossil fuels. It’s preferred that bio-based products are made from waste materials, as opposed to raw materials, to prevent additional environmental stressors and land use change. One of the most popular bio-based plastics is polylactide (PLA), which is generally certified compostable; however, not all bio-based plastics are completely biodegradable or compostable, including bio-polyethylene (PE) and bio-polyamide (Nylon 11), which act similarly to petroleum-derived plastics. There are some emerging bio-derived plastics, including polyhydroxyalkanoates (PHA), which show promising characteristics of being compostable and completely biodegradable, even in landfills and marine environments, but this technology is still in development, and certifications will clarify which standards this product meets.

Biopolymers

Biopolymers are materials made by living creatures, and include chitin, lignin, cellulose, protein fiber and plant polyester, to name a few. Much of the emerging materials for plastic substitutes are made from biopolymers. Because these materials are made directly from living creatures, they are expected to be compostable, completely biodegradable, and ideally marine degradable within a reasonable timeframe, but additional research and policy guidance need to be conducted to provide assurance. Just like with bio-derived plastics, biopolymers can be processed in manner that makes them have the same long-lasting characteristics as petroleum-based plastics.

Petroleum-based Plastics

Petroleum-based plastics are essentially conventional plastics: cheap, plentiful, and highly resistant to biodegradation, regardless of environmental conditions. This resistance is actually a sought after quality during the product’s use phase, but dangerous for end of life. These materials have not been shown to biodegrade in our lifetime, even with controlled experiments using a wide range of microorganism strains. Additionally, these plastics extend our reliance on harmful fossil fuels, as they are made from either naptha (crude oil) or ethane and propane (natural gas). Petroleum-based plastics also release potent greenhouse gas emissions including methane when exposed to sunlight and during degradation.

Summary

Established Compostability & Biodegradability Standards

To help alleviate the problem of inconsistencies across definitions of terms like compostable and biodegradable, national and international standards have been developed. These standards aim to provide clear, specific, and approved definitions, as well as established testing methodologies and other requirements to provide assurance that labeled products actually meet favored qualities. These standards help reduce the potential for greenwashing and mislabeling. When it comes to bioplastics, it is advised to not trust a product that claims its "biodegradable" without having an associated certification.

Here's an example of the requirements that a product must meet to be labeled as "compostable" under ASTM or CEN standards:

“Biodegradability is determined if 60%-90% conversion of carbon into carbon dioxide within 180 days pending polymer mix. Disintegration is measured by sieving the material to determine the biodegraded size and less than 10% should remain on a 2mm screen within 120 days. Eco toxicity is measured by having concentrations of heavy metals below the limits set by the standards and by testing plant growth by mixing the compost with soil in different concentrations and comparing it with controlled compost.” - World Centric

There are also many standardized testing methods related to compostability, biodegradability, disintegration, ecotoxicity and more, which are often used in evaluation criteria requirements. But for packaging and end products, the meaningful standards are those specified as meeting "evaluation criteria", such as those listed below.

Notable Compostability and Biodegradability Standards

• ASTM D6400 Standard Specification for Compostable Plastics (evaluation criteria for labeling "compostable")
• TUV OK Compost Home (evaluation criteria for labeling "home compostable")

While there are several standards, these are the only two that are legally authorized in the state of California. In 2013, the state passed a law that restricts the use of terms "biodegradable", "compostable", or similar claims for all plastic items and packaging, including those mixed with bio-based materials, unless the material is certified by ASTM D6400 or TUV Home Compostable at the time of sale.

New law extends existing restrictions to all plastic products, whether the product is made of plastic alone or in combination with other material, including containers, bags, straws, lids, utensils, any consumer product and any kind of packaging. (Pub. Res. Code, §§ 42355-42358.5 (2011) [effective Jan.1, 2013].)

Other evaluation criteria standards not accepted by the state of California include: ISO 17088-2012: Specifications for Compostable Plastics (evaluation criteria for labeling "compostable"); CEN EN 13432:2000 Requirements for Packaging Recoverable through Composting and Biodegradation (evaluation criteria for labeling packaging as "compostable"); TUV OK Compost INDUSTRIAL (evaluation criteria for labeling "industrial compostable"); TUV OK Marine (evaluation criteria for labeling "marine degradable"); AS 5810-2010 (evaluation criteria for labeling "home compostable").

While compostability standards and certifications are helpful in understanding the true biodegradability and disintegration of products, even certified bioplastics don't always perform in the field. Tests to meet certification requirements happen in a lab, which are designed to simulate industrial composting conditions, but they are not always accurate. To aid in field testing the true compostability of bioplastics, The Compost Manufacturing Alliance tests products in the field, and publishes a list of the products that actually compost as advertised. Additionally, several bioplastics and plastic alternatives have been documented to have high traces of harmful chemical additives known as PFAS, and other fluorinated chemicals. To aid in increasing transparency on potential fluorine contaminants and exposure, the Center for Environmental Health put together this Database of Single-Use Food Service Ware Products Tested for Fluorinated Additives. So when considering the use of bioplastics, please be sure to look for (1) a reusable alternative, (2) a verified compostable standard, (3) confirmation that the product breaks down in actual industrial composting facilities, (4) a local composting facility that accepts bioplastic and has a separate waste management stream to ensure that your waste product reaches the facility and (5) assurance that the product does not have high traces of fluorinated additives.

Conclusion

Suggested Order of Operations for Product Selection

1. Reusable glass, stainless steel, or recycled wood
2. Recycled wood or paper without PFAS lining, single-use
3. Try to avoid: Bioplastic, starch or PLA

Substantial efforts are underway by polymer scientists to develop viable bioplastics. However, “None of the [current] alternatives are what they should be,” Daniella Russo, the Plastic Pollution Coalition’s executive director, says. “For an alternative plastic to succeed, it should be non-toxic over its entire life cycle, fully biodegradable in all situations, and cost competitive.” Jacqueline McGlade, chief scientist at the UN Environment Programme, believes that biodegradable plastics are a 'false solution'. “It’s well-intentioned but wrong. A lot of plastics labelled biodegradable, like shopping bags, will only break down in temperatures of 50C and that is not the ocean. They are also not buoyant, so they’re going to sink, so they’re not going to be exposed to UV and break down."

Also keep in mind that although these products may be made from plant rather than petroleum raw materials, the basic chemical structure (PET, LDPE, PVC, etc.) of the plastic bag or bottle is still the same. Equally important to remember is that these bags or bottles are still single use plastics. Reusable bags, bottles or other containers are a much better alternative for the ocean and for your wallet.

See a great infographic on why bioplastics are not the solution plastic pollution here.

Additional Surfrider Resources

• A Guide to Bioplastics and Compostable Phone Cases Coastal Blog
• List of US Composting Facilities & Operations
• Better Alternatives Now (BAN) List 2.0
• Bioplastics Beachapedia article

References