Globally, humans use over 5 trillion plastic bags every year. This is an exceptional volume of plastic, which has enormous environmental consequences. Plastic bags are not biodegradable, meaning they cannot be organically broken down by organisms. Instead, it takes approximately 1000 years for plastic bags to photodegrade by light. This results in microplastics which pollute drinking water, are consumed by animals and cause health issues in both humans and animals. During degradation many plastic bags are blown around the environment by the wind, causing them to enter waterways, blocking storm drains and polluting oceans.
The material which single-use plastic carrier bags are made of, Polyethylene, was created in 1933 in Northwich, England when a manufacturing error resulted in its accidental creation (UN Environment Programme, 2021). The material was then first utilised by the British Army during WW2, mainly for small radars installed onto ships and airplanes.
In 1965, a Swiss engineer working for the company Celloplast, designed and manufactured the world’s first single-use plastic carrier bag, using Polyethylene. The invention very quickly spread across stores in Europe.
In 1979, plastic carrier bags began to pop-up in large corporations with ExxonMobil in the United States, being the first noted company to offer its customers plastic bags.
In 1997, the Great Pacific Garbage Patch was discovered between California and Hawaii. A significant amount of the debris was made up of single-use plastic bags, prompting people to begin reflecting on the environmental impact of these items.
Plastic carrier bags are heavily relied on by both producers and consumers due to their desirable properties. Polyethylene is cheap to produce, strong, durable and resistant against heat and chemicals, making it the perfect solution to carry groceries or other purchases. The life cycle analysis of plastic carrier bags has proven they are harmful to the environment from ‘cradle-to-grave’. This means both production and disposal have negative impacts on the environment. The diagram below shows a process flow diagram of the inputs and outputs for plastic bag manufacturing use and end-of-life (Greene, 2011).
The consequences of disposing plastic bags are worse than production. As discussed earlier, polyethylene is non-biodegradable and instead photodegrades from light exposure. Plastic bags buried deep in landfill receive little light and therefore take an extremely long time to degrade. During the degradation process, polyethylene breaks down into tiny particles known as microplastics.
Microplastics are extremely harmful to both animals and the environment. As they are so small, they freely move around in the air and water making them easily consumable. When microplastics enter the bloodstream, they are toxic and can have dangerous health consequences on the digestive system and cardiovascular health. Microplastic concentrations in human blood is constantly increasing (Campen et al., 2024). This is due to the continuous use of single-use plastics, which pollute the environment, are consumed by animals and consequently ingested by us.
Plastic bags are also one of the leading causes in animal suffocation, specifically marine mammals. A commonly known fact is that sea turtles are prone to suffocating on plastic bags in the ocean due to misperceiving them for food – jellyfish (Huang, 2017). The Worldwide Wildlife Fund estimate that 100,000 marine mammals die each year from plastic pollution in oceans (WWF, n.d). The diagram below illustrates how plastic items dominate ocean rubbish, with plastic bags making up the largest contributor of 14.1%.
Another problem with plastic bags is their tendency to reach and block drainage systems. This includes sewage pipes, which overflow with hazardous waste, spreading bacteria and diseases that contaminate clean water sources. Additionally, with the increasing impacts of climate change, plastic bags obstruct storm drains, preventing them from functioning properly and leaving areas vulnerable to flooding during extreme weather events.
A common misconception is that paper bags are better for the environment. However, a life-cycle assessment has shown that the production of paper bags requires more resources than plastic bags. In a study of the production of 1000 paper bags vs 1500 plastic bags, a higher volume of energy, fossil fuels, water and solid mass was required to produce fewer paper bags than plastic – shown below (Greene, 2011).
However, paper bags are certainly more easily recycled. This is mainly because of the paper fibres, which are more natural making it easier to decompose and separate during the recycling process. Paper is more widely accepted than polyethylene and it is able to be recycled a number of times more than plastic can be.
The most sustainable option is a reusable carrier bag, which are designed to be used until it can no longer serve its purpose. Ideally, such a bag should last for several years and only be replaced when it is no longer functional (not for aesthetic reasons or to follow trends) in order to minimize its environmental impact. Unfortunately, recent trends in consumption means this is not the case, and people are actually purchasing multiple reusable bags a year, counteracting their entire purpose.
| Sources: Campen, Nihart, Garcia, Liu, Olewine, Castillo, Bleske, Scott, Howard, Gonzalez-Estrella, Adolphi, Gallego, Hayek (2024) Bioaccumulation of Microplastics in Decedent Human Brains Assessed by Pyrolysis Gas Chromatography – Mass Spectrometry. Available at https://pubmed.ncbi.nlm.nih.gov/38765967/ [Accessed 22 November 2024] Greene (2011) Life Cycle Assessment of Reusable and Single-use Plastic Bags in California. Institute for Sustainable Development. California State University, California.Available at https://plasticsparadox.com/wp-content/uploads/2021/01/Life-Cycle-Assessment-of-Reusable-and-Single-use-Plastic-Bags-in-California.pdf [Accessed 20 November 2024] Huang (2017) Ecologies of Entanglement in the Great Pacific Garbage Patch. Journal of Asian American Studies. 20, (1), p. 95-117. Available at https://muse.jhu.edu/pub/1/article/647481/pdf [Accessed 8 December 2024] Morales-Casales (2021) Plastic items dominate ocean garbage. Infographic. Available at https://www.statista.com/chart/25056/waste-items-polluting-oceans/ [Accessed 11 December 2024] Qiying (2014) The California Plastic Bag Ban: Where Do We Go From Here? Arizona Journal of Environmental Law & Policy. 5, (2). Available at https://repository.arizona.edu/handle/10150/675169 [Accessed 11th December 2024] UN Environment Programme (2021) From birth to ban: A history of the plastic shopping bag. Available at https://www.unep.org/news-and-stories/story/birth-ban-history-plastic-shopping-bag [Accessed 10 December 2024] WWF (n.d) Pollution. Available at https://wwfwhales.org/pollution#:~:text=Globally%2C%20100%2C000%20marine%20mammals%20die,a%20result%20of%20plastic%20pollution. [Accessed 5 December 2024] |
