“Are biodegradable plastic bags good for the environment” is a question directed towards solving plastic waste accumulation and pollution.
The world we live in is choking on plastic, and more waste is dumped in landfills or incinerated. This causes a huge pollution problem that affects human health and wildlife.
Biodegradable and compostable plastic was the invention to replace conventional plastic, which takes forever to decompose. These superior alternatives to petro-based plastics gained popularity in the early 1990s. They have been commercially available since then, but people are sceptical about their biodegradability.1
Many plastics labelled “biodegradable” only disintegrate and not biodegrade. In recent times, experts have conducted research to ascertain the rate at which this sustainable alternative to plastics degrades in nature. The results from the research show that they do not 100% decompose after an observed length period.
What Are Biodegradable Plastic Bags?
The term “biodegradable” means capable of being decomposed by biological activity, particularly by microorganisms, which is how these plastic bags are described. Biodegradable plastic bags are products derived from plant-based materials, and they are said to be susceptible to the activity of microorganisms and break down under controlled conditions.
These plastic bags were made to reduce the frequent use of conventional plastic bags, a non-biodegradable material littering landfills and polluting our waterways. Plastic pollution is a threat to human health and ecosystems.
“Single-use plastic bags are a huge source of litter worldwide. We wanted to test whether biodegradable plastic bags would help reduce plastic pollution” says Richard Thompson, a marine biologist in the United Kingdom at the University of Plymouth.
According to the ASTM (formerly known as American Society of Testing and Materials) D6400, biodegradable plastic is “a plastic that degrades because of the action of naturally occurring microorganisms such as algae, bacteria, and fungi”.
The standard organization also describes compostable plastic as “a plastic that undergoes degradation by biological processes during composting to yield carbon dioxide, inorganic compound, water, biomass at a rate consistent with other known compostable materials and leaves no visually distinguishable or toxic residue”.
BP bags are considered non-toxic and only produce about 32% of greenhouse gas emissions compared to conventional plastics. Energy consumption during the manufacturing process also differs, as biodegradable plastics only require 35% of the energy needed to produce petroleum-based plastics.2
Learn more: Biodegradable Vs. Compostable: What is the Difference?
Effects of Plastics on the Environment
Plastics are non-biodegradable materials that persist in nature. They may never fully decompose at the end of their useful life. The best they can do is photodegrade (break down into microplastics that still cause irreparable environmental harm).3 They contaminate water bodies, suffocate marine life, and impact global warming. Despite the negative effects of plastics, the lightweight materials are still widely used and poorly disposed of.
On average, millions of tons of plastic waste are sent to landfills. Plastic waste has reached the deepest part of the ocean, building on the surface with the Great Pacific Garbage Patch as an example.
Plastic in the ocean poses a threat to marine life, especially endangered species. Human activity on the beach and waste dumped into streams, rivers or lakes is being carried into the ocean, leading to marine species being entangled in or ingesting plastic.
What Are Biodegradable Plastic Bags Made Out of?
Biodegradable plastic bags can be biobased or petrol-based. When they are petrol-based, it means that they are produced with similar ingredients to regular plastic bags. However, they are manufactured in a way that disintegration can occur within a shorter period compared to conventional plastics.4
Since they are not 100% biodegradable and are made with a similar makeup as traditional plastics, their decomposing process will leave a toxic residue that can enter the food chain, posing potential health and environmental risks.
Types of Biodegradable Plastics
Polylactic Acid (PLA)
Polylactic acid is made from natural resources like sugarcane, cornstarch, potato chips or cassava roots. PLA is a type of biodegradable plastic widely used in food packaging, industrial applications, household goods, and in medical field.
However, polylactic acid may be made from natural materials, but this doesn’t mean that they are 100% sustainable for the environment.5
Polyglycolic acid (PGA)
This is another type of biodegradable plastic made from glycolic acid. It’s produced by fermenting natural carbohydrates such as corn, sugarcane, and sugar beets.
It’s estimated that about 80% of polyglycolic acid accumulates mostly in the ocean where they begin to break down to form microplastics that harm marine species. So, PGA is also not 100% sustainable for a healthy environment.
Polyhydroxyalkanoate (PHA)
Polyhydroxyalkanoate (PHA) is made from the natural fermentation of sugar and they are commonly used to make medical devices. PHA can be biodegradable in soils but when mixed with other materials, the biodegradation process will be affected due to a change in the polymer properties.6
Polybutylene Succinate (PBS)
Polybutylene succinate is a type of biodegradable plastic derived from natural sources. It’s a thermoplastic with the ability to biodegrade into water and carbon dioxide through the biological activities of microorganisms.7 PBS is a sustainable plastic that doesn’t emit greenhouse gasses while it’s being produced. Their environmental impact when disposed of is low.
Learn more: 10 Best Biodegradable Diapers
Polyvinyl alcohol (PVA)
PVA is a type of biodegradable plastic made from vinyl acetate. It’s a colourless and odourless material used in various industries and applications like coatings, packaging, adhesives, paper etc. PVA can disintegrate into non-toxic components when it’s exposed to microorganisms and moisture.8 They are more sustainable to use than conventional plastics.
Cellulose Acetate (CA)
Cellulose acetate is derived from cellulose, the main substance found in the walls of plant cells. This type of biodegradable plastic contains physical and chemical properties that make it a fine flexible material.
Plastics made with cellulose acetate can break down into the environment. They can disintegrate into cellulose and acetic acid through the biological activity of water in the environment.9
Are Biodegradable Plastic Bags Good for the Environment?
Biodegradable plastics, or BPs for short, have become the focus of recent research in the past few years to evaluate the biodegradability of the materials and to substantiate reasons why these materials should be a sustainable alternative to conventional plastics. If proven to be 100% biodegradable, then we would expect a reduction in global plastic waste generation.
However, the result is not convincing to prove that biodegradable plastics can be the best alternative to plastics to reduce global plastic pollution.
The fact remains that BPs require certain environmental conditions to degrade and these conditions are not always reliably present in the natural environment.
Oxo-biodegradable plastic is said to break down rapidly compared to traditional plastics when exposed to oxygen, while compostable plastics supposedly disintegrate into compost only when they are placed in compost with the perfect temperature and humidity.
According to a 2015 report by the United Nations, oxo-degradable plastics are a risk to marine ecosystems, and this UN report went on to highlight the environmental effect of oxo-degradable plastics.
According to UNEP, toxic microplastics in the ocean can be injected by marine organisms, which will likely cause the transmission of harmful algae species, microbes, and pathogens.
Can Biodegradable Plastics Solve the Problem of Environmental Plastic Accumulation?
Biodegradable plastics are not 100% biodegradable in nature, which is not all that helpful in solving the problem of global plastic waste pollution.
The petrochemical industry is fast-growing and this means improved productivity in making more of these lightweight materials. Poor waste management in local communities and even in cities contributes to the waste problem polluting our planet.
Recycling remains the best option for reducing plastic waste but poor waste management increases the pile of waste in landfills and incineration of these non-biodegradable materials is still widely practised.10
Learn more: 13 Examples of Biodegradable and Non-Biodegradable Waste
How Long Does it Take for a Biodegradable Plastic Bag to Decompose?
It’s still not 100% guaranteed that biodegradable plastic bags are good for the environment, and their environmental effect will depend on the kind of material used to manufacture them. However, Biodegradation of BP’s bags supposedly takes about 3 to 6 months on average under the right conditions.
The decomposition of BPs may depend on various factors such as temperature and the amount of moisture in the environment. An average temperature of over 50 degrees Celsius (122 Fahrenheit) is required to start the decomposition process.11
This shows that what is always dubbed “biodegradable” is not always 100% environmentally friendly.
Biodegradable plastic bags Disposed of in Different Environments (A research study conducted by the University of Plymouth’s International Marine Litter Research Unit)
A study was carried out at the University of Plymouth by Imogen Napper and Richard C. Thompson to observe biodegradable plastics as a sustainable alternative to reduce ocean plastic pollution.
The experiment is focused on how fast five types of plastic bags widely used in the United Kingdom littering streets will decompose in different environmental conditions.
Materials included in the experiment are an oxo-biodegradable bag, a biodegradable bag, regular plastic bags, specifically made of HDPE, and a compostable.
These plastic carrier bags were exposed to certain environmental conditions – left in places where they would likely end up if they were improperly disposed of. They dumped the bags in the open air, the sea, and had some buried under the earth.
The researchers closely observed how decomposition was happening by testing the bags at regular intervals. Their observation was focused on changes in material strength, chemical structure, and texture.
The experiment was conducted to see what was left of the bags after three years. The biodegradable bags, ox-biodegradable bags, and standard plastic bags after three years exposed in the soil or the sea did not completely biodegrade.
The compostable bag decomposed in the marine environment in the first three months. All bag material exposed in the open air disintegrated into fragments after 9 months.
Based on the findings of this experiment, the results showed that none of the selected bags exhibited any substantial deterioration when exposed to the open air, marine environment, or soil over three years.
“This research raises several questions about what people might expect when they see something labelled as biodegradable. It concerns me that these novel materials also present challenges in recycling” Richard Thompson said.
What Are the Potential Risks of Using Biodegradable Plastics to the Environment?
Biodegradable plastics do not 100% biodegrade in nature and their decomposition process has a potential impact on the environment.
When these materials are improperly disposed of, two things are guaranteed to occur in the environment. They either disintegrate or accumulate in our surroundings and like conventional plastics, biodegradable plastics can fragment into microplastics and nanoplastics.
Conclusion
Plastic in the ocean poses a threat to marine life, especially endangered species. Human activity on the beach and waste dumped into streams, rivers or lakes is being carried into the ocean.
Biodegradable plastic bags are presented as a sustainable alternative to conventional plastics but recent research shows that these materials are not that good for the environment.
Sources
- Magdalena Vaverková et al: “STUDY OF THE BIODEGRABILITY OF DEGRADABLE/BIODEGRADABLE PLASTIC MATERIAL IN A CONTROLLED COMPOSTING ENVIRONMENT. : DOI: 10.2478/v10216-011-0025-8″ ↩︎
- Shaikh, S., Yaqoob, M., & Aggarwal, P. (2021). An overview of biodegradable packaging in food industry. Current Research in Food Science, 4, 503–520. ↩︎
- Pia Skoczinski & Michael Carus: “Enzymatic Plastic Degradation.” ↩︎
- Moshood, T. D., Nawanir, G., Mahmud, F., Mohamad, F., Ahmad, M. H., & AbdulGhani, A. (2022). Sustainability of biodegradable plastics: New problem or solution to solve the global plastic pollution? Current Research in Green and Sustainable Chemistry, 5, 100273. ↩︎
- Why is PLA not sustainable? | Swiftpak. (2023, October 24). Swiftpak. ↩︎
- Miguel Fernandes et al: “Factors affecting polyhydroxyalkanoates biodegradation in soil.” ↩︎
- EuroPlas. (2023, September 17). Different types of biodegradable plastics. EuroPlas. ↩︎
- Snow. (2023, March 22). What is PVA (Polyvinyl Alcohol)? Is it Eco-friendly? GREEN ECO DREAM. ↩︎
- Sustainability｜Daicel corporation – Cellulose acetate. (n.d.). ↩︎
- Kibria, M. G., Masuk, N. I., Safayet, R., Nguyen, H. Q., & Mourshed, M. (2023). Plastic waste: Challenges and Opportunities to Mitigate pollution and Effective management. International Journal of Environmental Research, 17(1). ↩︎
- Afshar, S. V., Boldrin, A., Astrup, T. F., Daugaard, A. E., & Hartmann, N. B. (2024). Degradation of biodegradable plastics in waste management systems and the open environment: A critical review. Journal of Cleaner Production, 434, 140000. ↩︎