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Clarification on Plastics: Recycling and Biodegradability

Author: Grace Enjia Xu

Editors: Hwi-On Lee, Misha Wichita

Artist: Grace Enjia Xu

We live in the Anthropocene epoch” is one of the most common phrases scientists may say when reflecting on our current society, where human actions have substantially impacted the environment and led to irreversible consequences — consequences we can see with our own eyes in the colorless skies, flaming wildfires, and contaminated oceans of today. A key contributor to the Anthropocene epoch and the human destruction of nature is inevitably plastic. In the current era, over 400 million tons of plastic are produced every year and are included in almost everything we use, manufactured within the packaging of our food, the electronics we buy, and even the houses we live in. While we enjoy the conveniences and benefits of plastic, the overconsumption of plastic has ultimately led to significant consequences that are beyond what our environment can take. These plastics are hardly biodegradable and consistently emit excessive amounts of greenhouse gases into the atmosphere, leading to not only global warming, but also the pollution of the ocean and soil hundreds of years after being made. However, overconsumption is not the only problem with plastic — the misconceptions people have about plastic being recyclable is also why these plastics are not being properly managed. Therefore, it is important to differentiate the many types of plastic to ensure the proper recycling and usage of each type.

There are seven different types of plastics that are commonly used. The usage of each plastic differs based on the amount of flexibility, sustainability, and safety needed in different situations. Polyethylene terephthalate (PET) is the first type of plastic. It is commonly used as a lightweight, strong, and transparent material for packaging and clothing. Seen in beverages and food, this type of plastic has a low melting point and can be recycled multiple times for different purposes. Furthermore, these recycled PET products release 90% less carbon dioxide emissions compared to virgin polyethylene terephthalate, making it very beneficial to recycle PET.  A prevalent recycling process for PET among different clothing and shoe brands is the recycling of plastic bottles into polyester yarn for clothing.  Nike, Adidas and Pentagonia all use recycled PET plastics for their clothes and shoes, especially Nike’s new collection of Space Hippie sneakers, which create minimal greenhouse gases and are made from recycled PET bottles. Therefore, it is important to always recycle this type of plastic to further improve the environment.

Other than PET plastic, high-density polyethylene (HDPE) is also a highly recyclable plastic that  is incredibly resistant. It is used for a wide variety of different products, from milk jugs and grocery bags to construction pipes and playground equipment. As opposed to high density polyethylene,  low-density polyethylene plastic, otherwise known as LDPE, is a thin plastic with extreme flexibility. The unique flexibility of polyethylene makes it a great material for cling-wrap and bubble-wrap — however, LDPE takes three to four hundred years to decompose.

Like LDPE, polyvinyl chloride (PVC) cannot be recycled as easily and should be avoided.  Polyvinyl chloride comes in two forms: rigid and flexible PVC, with the former being used for doors, pipes, and building materials, whereas the latter is often used for wiring and electric cable insulation. Despite its multifaceted uses, PVC is rarely reused industrially, let alone by a majority of people every day. It is not a recommended plastic, so it is important to avoid its usage if possible.

The fifth type of plastic is polypropylene (PP), which has hard, sturdy physical properties. It can be recycled and is generally considered one of the safer plastics. PP can withstand high temperatures and is used to build thermal vests, car parts, and other containers. Like PET, the polypropylene can also be used in clothes by recycling it into fabrics. Polypropylene can also be recycled into battery cables and storage racks, making it a convenient, recyclable plastic that can be used in versatile ways.

On the other hand, polystyrene (PS), or styrofoam, is not considered as safe and is notoriously known as being the most environmentally unfriendly plastic. PS is used nearly everywhere from cups, utensils, and food packaging, to insulation and packing materials. However, styrofoam is detrimental to the environment and cannot be recycled. Pieces of styrofoam thrown into the ocean can float and later be mistaken as food by marine animals. Not only is it considered hazardous to animals, but it is also considered a human carcinogen. Carcinogens or toxic chemicals such as styrene can be absorbed by food packaged in polystyrene. Polystyrene is not accepted by recycling programs and cannot biodegrade into Earth — thus, PS should be avoided, especially if in foods. The final plastic is referred to as an “other plastic” and does not fall into the other categories mentioned thus far; they are controversial and cannot be recycled most of the time. 

Aside from the most common types of plastic, there are also sustainable biodegradable types of plastic such as PLA, also known as polylactic acid or polylactide, made from renewable biomass. PLA is typically made from the fermented plant starch of sugarcane, corn, and cassava. It can be used for food packaging, textiles, medical implants, and 3D printing. 

The production of PLA seems promising: humans have finally produced a biodegradable material that can be depended on in the future to simultaneously solve our needs and protect the environment. But unfortunately, PLA cannot be relied on forever. Whilst PLA is known to be biodegradable and beneficial for the environment, this process is not as simple as we may think. Instead, PLA needs to be broken down through industrial compostable processes or anaerobic digestion. This means that the majority of 3D printing waste cannot be biodegraded through industrial processes, causing such waste to end up in landfills instead. Recycling could be another approach to the problem by creating a ‘closed loop’, converting PLA waste into 100% recycled filament for further use. 

Although humans are aware of the disadvantages of plastic consumption, its convenience and usage in our daily lives cannot be erased. While eradicating the existence of plastic is nearly impossible today, we can continue spreading awareness and information on the recyclability and safety of different plastics to reduce its negative environmental effects. In doing so, we can debunk the common belief that all plastics are recyclable and biodegradable for the benefit of the modern world.



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