Ethan Clarke
Biodegradable plastics are designed to break down completely into substances found in nature within a reasonable timeframe. However, the effectiveness of biodegradable plastics in achieving this purpose is questionable. While some biodegradable plastics can be composted, they are not always fully compostable and may require specific conditions, such as temperature, pressure, and nutrient concentration, found only in industrial composting facilities. Additionally, biodegradable plastics may not always be recyclable and can end up in landfills, where they may never decompose due to the absence of light and oxygen. Furthermore, some biodegradable plastics may fragment into smaller pieces, leading to soil pollution, increased risk of ingestion by animals, and water contamination. Recent advancements have been made to enhance the biodegradability of plastics, such as embedding polymer-eating enzymes, but challenges remain in ensuring their effectiveness in various environmental contexts.
| Characteristics | Values |
|---|---|
| Definition | Biodegradable plastic is defined by its ability to break down completely into substances found in nature, in a reasonable timeframe. |
| Composting | Biodegradable plastic is designed to break down in industrial composting facilities, requiring specific conditions like temperature, moisture, pressure, and nutrient concentration. Some biodegradable plastics are designed to break down in home compost piles. |
| Labelling | Biodegradable plastics rarely carry a recycling symbol and are often labelled with a #7 recycling code, indicating they are not accepted by local municipal recyclers. |
| Limitations | Biodegradable plastics may not fully degrade in natural environments, especially in the absence of light, oxygen, warmth, and microorganisms. They can end up in landfills or oceans, causing similar environmental harm as conventional plastics. |
| Alternatives | Compostable and bioplastic goods are sometimes preferred over biodegradable options as they are made from plant biomass and can be composted or broken down biologically. |
| Additives | Biodegradable plastics may contain extra chemicals or additives to accelerate degradation, such as enzymes, oxidizing agents, or polymer-eating enzymes. |
| Greenhouse Gas Emissions | Bioplastics produce fewer greenhouse gas emissions over their lifetime due to the absorption of carbon dioxide by the source plants during growth. |
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What You'll Learn
Biodegradable plastics are rarely recyclable
Biodegradable plastics have a #7 recycling code on them, which places them in the "Other" category of plastics. #7 plastics are generally not accepted for recycling by local municipal recyclers due to the addition of chemical additives. Bioplastics and "compostable" plastics are often made from plant biomass, such as corn starch, sugarcane, or wheat, and should either completely and rapidly break down biologically or be compostable. This means they are supposed to break down into biological elements, unlike conventional plastics.
However, while some bioplastics can be composted and do not harm the quality of the compost, others leave toxic residues or plastic fragments behind, making them unsuitable if the compost is being used to grow food. Additionally, the use of plant material for bioplastics raises concerns about the use of genetically modified crops, the use of farmland that could otherwise be used to grow valuable food crops, deforestation, the use of freshwater supplies, and soil erosion.
Commercial composters reach temperatures and humidity levels that cannot be achieved in a standard garden composter, so bioplastics may never break down at home. Some commercial composters, like those in Northern California, have to remove bioplastics like compostable utensils because even their temperatures and humidity levels will not break down these products. Sending these items to a landfill may be the best way to dispose of them, as in a landfill, they won't contaminate recycling or compost streams. However, for biodegradation to occur, three basic resources are required: heat, light, and oxygen. In a landfill site, waste is entombed, creating a complete absence of light and oxygen, so a biodegradable plastic or bioplastic may never decompose.
Biodegradable and compostable plastic alone will not solve the plastic pollution crisis. All plastic, including biodegradable and compostable types, must be collected and paired with the right recovery systems to keep the material out of nature.
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Compostable plastics require specific conditions to break down
Compostable plastics are biodegradable, but not all biodegradable plastics are compostable. Compostable plastics are designed to be processed in either home or industrial composting facilities, which enable specific conditions like temperature and moisture to turn the plastic into usable soil conditioner.
The conditions required for compostable plastics to break down include heat, light, and oxygen. In a landfill site, waste is entombed, creating a complete absence of light and oxygen. If a biodegradable plastic or bioplastic ends up in a landfill site, it may never decompose.
Biodegradable plastics are tested to ensure they break down under controlled conditions in a lab, including factors such as oxygen levels, UV exposure, and temperatures. However, nature does not have controlled conditions, so it is uncertain whether biodegradable plastic will actually biodegrade in the natural world if it is littered.
The term "biodegradable" includes a time component regarding the length of time it takes for the plastic to fully degrade. According to the Federal Trade Commission's "Green Guides", it is deceptive to make an unqualified degradable claim for items entering solid waste streams if they do not completely decompose within a year after customary disposal. Unfortunately, nature does not present conditions for complete decomposition within a year.
Compostable materials are designed with biodegradability in mind, transforming back into the earth and contributing positively to the environment. They break down into compost, a process that typically completes within a few months under optimal conditions. As they break down, they form nutrient-rich compost, which enhances soil health and supports plant growth.
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Biodegradable plastics are not always compostable
Biodegradable plastic is tested to make sure that it breaks down under controlled conditions in a lab, including factors such as oxygen levels, UV exposure, and temperatures. However, nature does not have controlled conditions, so it can never be certain that biodegradable plastic will actually biodegrade in the natural world if it is littered. When these materials do not break down, they have the same consequences as their non-biodegradable counterparts—polluting the ecosystems and habitats that both nature and humans depend on and contributing to the plastic pollution crisis.
The prefix “bio” can be misleading: plastics do degrade, but not into something biological. They break into smaller and smaller pieces of plastic. Some biodegradable plastics fragment rather than biodegrade, breaking into small pieces that can pollute soils, increase the risk of ingestion by animals, and end up in oceans and waterways. These kinds of plastics are impossible to recover for recycling and are not suitable for composting.
Biodegradable and compostable plastic alone will not solve the plastic pollution crisis. All plastic—including biodegradable and compostable types—must be collected and paired with the right recovery systems to keep the material out of nature. Compostable takeout containers, for example, can compost the remaining food residue alongside the container itself, which can be helpful in reducing waste. However, compostable and biodegradable plastic can contaminate the recycling stream, so it is important to check local recycling guidelines and only recycle items that are accepted.
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Biodegradable plastics are made from the same materials as conventional plastics
Biodegradable plastics are designed to break down completely into substances found in nature within a reasonable timeframe. However, they are rarely recyclable and often end up in landfills. Biodegradable plastics are made from the same materials as conventional plastics, typically derived from petroleum, but with additional chemicals that cause them to break down more rapidly when exposed to air and light. These extra chemicals can cause biodegradable plastics to fragment rather than biodegrade, resulting in small pieces that can pollute soils, increase the risk of ingestion by animals, and end up in oceans and waterways.
Conventional plastics are derived from natural gas processing and feedstocks obtained from refining crude oil, which can last forever in the environment. In contrast, biodegradable plastics are often produced with renewable raw materials, such as plant biomass like corn starch, sugar cane, or wheat. These bioplastics are designed to break down into biological elements, but they may require specific conditions, such as high temperatures and moisture, found in industrial composting facilities.
The distinction between biodegradable and conventional plastics lies in their ability to break down. Biodegradable plastics are designed to degrade, but the process may not always occur naturally in the environment. Nature lacks the controlled conditions of a laboratory, where biodegradable plastics are tested for factors like oxygen levels, UV exposure, and temperature. As a result, biodegradable plastics may not biodegrade as intended when littered, leading to the same environmental consequences as their non-biodegradable counterparts.
To address the limitations of biodegradable plastics, researchers have developed new processes to make them truly compostable. One approach involves embedding polymer-eating enzymes in the plastic to enable programmed degradation. These enzymes, activated by heat and moisture, can break down the plastic from the inside, reducing it to harmless chemical building blocks. Another study focuses on creating biodegradable polymers for single-use plastics, aiming to solve the problem of non-biodegradable materials in this domain.
While biodegradable plastics offer an advantage in terms of microbial degradation, they are not a panacea for the plastic pollution crisis. The solution requires a multifaceted approach, including reducing, reusing, and properly disposing of plastics, along with exploring alternative materials and production methods.
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Biodegradable plastics are not always biodegradable
Biodegradable plastics are tested in labs under controlled conditions, including factors like oxygen levels, UV exposure, and temperature. However, nature does not provide these controlled conditions, so biodegradable plastics may not actually biodegrade if littered. Instead, they can fragment into microplastics, polluting ecosystems and contributing to the plastic pollution crisis.
The prefix "bio" can be misleading. While biodegradable plastics do degrade, they do not break down into something biological. They can disintegrate into smaller and smaller pieces of plastic, which can have harmful environmental consequences. For example, these microplastics can pollute soils, increase the risk of ingestion by animals, and end up in oceans and waterways.
Additionally, biodegradable plastics are very rarely recyclable. They often end up in landfills, where they may never decompose due to the absence of light and oxygen. Even when sent to composting facilities, biodegradable plastics may not break down as intended and can leave behind toxic residues or plastic fragments.
The production and disposal of biodegradable plastics must be carefully managed to ensure they actually biodegrade. As such, biodegradable plastics alone are not a solution to the plastic pollution crisis. Instead, a comprehensive approach that includes reducing, reusing, and properly disposing of plastics is necessary to address this issue effectively.
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Frequently asked questions
Biodegradable plastics are plastics that can be decomposed by the action of living organisms, usually microbes, into water, carbon dioxide, and biomass. They are made from the same materials as conventional petroleum-based plastics but with added chemicals to help them break down more rapidly when exposed to air and light.
Biodegradable plastics are designed to break down completely into substances found in nature, and in a reasonable timeframe. However, they often require very specific conditions to do so, such as temperature, pressure, and oxygen levels, which are hard to replicate outside of industrial composting facilities. Therefore, they may not break down as intended if littered or sent to landfill.
Biodegradable plastics are rarely recyclable and are not the same as compostable plastics, so they often end up in landfills. Some biodegradable plastics also fragment rather than biodegrade, breaking into small pieces of plastic that can pollute soils and oceans, and be ingested by animals. They also require more chemicals to produce than conventional plastics, and the use of plant material for bioplastics has been criticised for encouraging the use of farmland and water supplies that could be used for food crops.
