Is plastic biodegradable? (challenges and misconceptions)

This blog spot will answer the question, “Is plastic biodegradable”? And include topics like what type of plastics are harmful to earth, the chemical nature of plastic that decides its biodegradability, alternative solutions to the use of plastic, and what steps are taken to control plastic pollution. 

Is plastic biodegradable? 

No, plastic is not biodegradable, at least not within the span of human life. They are made of materials that are tough to break by any microorganisms and it stays in our earth for millions of years. Bacterias and fungi have not evolved to produce the kind of enzymes that can biodegrade plastic in any condition.

Plastics are in turn designed to have a long life with multiple purposes. Over 5 billion tons of plastic have been used since it was first made and its production is increasing exponentially. We are dealing with this amount of plastic waste even today because of its non-biodegradability. 

Plastic has overtaken the role of paper and naturally occurring eco-friendly materials. Many plastic products are user friendly, durable, not biodegradable and last longer. It is much difficult to get these feasibility from any other naturally occurring materials. Hence plastic plays a necessary role in everybody’s day to day activity.

What makes plastic non-biodegradable?

A set of factors has to be considered to answer this question. Biodegradability of plastic depends mostly on its molecular weight, type of functional group attached to the polymer, and its surface to volume ratio. 

Some functional groups present in the polymer chain allow for faster degradation by enzymatic erosion process in an abiotic condition. Whereas, plastic polymers without any functional group such as polystyrene, takes longer time to degrade by microbial enzymes. 

The chemical structure of a plastic monomer decides its physical property. Most of the plastics are non-degradable as the chemical chain is unbreakable or takes 1000s of years to degrade with any enzymatic process by the naturally occurring microorganisms.

Moreover, in a landfill where conditions are unfitting, these plastics break down slowly, taking millions of years for the biodegradation process to happen. The conditions such as temperature, humidity, aerobic or anaerobic conditions also play a key role in biodegradation of plastic.

There are different ways by which plastics are made and each have different rates of biodegradation with polyesters taking a higher amount of time than polyamides or polyolefin plastics. Presence of functional moiety on plastic polymer also affects its biodegradation. 

Plastics are polymers made from repeated units of ethylene or other carbon based monomers. Some of the names include polyethylene terephthalate or polyvinyl chloride. Making of plastic utilizes natural and organic raw materials such as coal, natural gas, and crude oil which are non-renewable and non-replaceable resources. 

Based on the application and demand several additives are used to make a robust lightweight plastic product. To increase the toughness, rubber is added, however, to increase its flexibility, plasticisers are added. In either case, the  biodegradability of the plastic is affected.

Moreover, for any substance to be biodegradable, it has to dissolve in water. However, plastic materials are insoluble in water and some are resistant to dilute acids. Since plastics are made to be water resistant for its various applications, there is nothing we can do to compromise the property with respect to its solubility.

Are we compromising the health of the environment with the use of plastic?

Starting from its synthesis to its disposal, plastics have been unfavorable to our earth in many ways. There are numerous challenges with respect to the disposal of plastic waste or in finding another source of raw material for making plastic. The following points highlight the effects caused by the use of plastic material.

  • Depletion of non-renewable resources
  • Economic cost to the environment
  • Deforestation
  • Pollution of water 
  • Death of numerous land and water animals
  • Toxic gasses emitted by burning of plastic

Making plastic requires tons of raw materials which are obtained from petroleum or other fossil fuels. The important fossil fuels used for plastic making include crude oil, natural gas, and coal. The impact of depletion of such raw materials will lead to an unfortunate effect on our environment.

According to the World Wildlife Fund (WWF), for the year 2019, the plastic waste pollution, emission, and cleanup expenses were around $3.7 trillion. This is a huge cost to our economy that is spend on protecting our land and marine ecosystems. 

Another way by which plastic affects the forest is by the formation of microplastics. These tiny plastic residues leach our toxic chemicals such as phthalates and Bisphenol A (BPA) that affect the natural flora of the environment. 

Microplastics end up in the stomach of many sea water fishes and when these are consumed by humans they end up in our body. Moreover, studies have shown that presence of microplastic has changed the behavior of earthworms in a way that affects the natural soil fertility.

The use of chlorinated plastic has been a major issue as these release harmful chemicals in soil that can sweep into underground water. We have seen numerous cases where marine animals are affected by the plastic wastes wrapped around their neck or in their throat. 

Plastic debris are the major pollutant of ocean waters and ingestion of these by the sea animals is a major reason for the alarming number of deaths.  

Though burning of plastic is banned in many countries, there still are places where plastic collection is improper and most of the residents discard the plastic waste by burning them. The toxic gasses emitted by burning plastics cause respiratory ailments and affect our immune systems. Some of them are potentially carcinogenic. 

What are the alternatives to plastic?

Innovations and smart ideas have led to the invention of much more eco-friendly materials that can replace plastic. However, researchers are yet to find a suitable option to completely replace plastic material. Currently, plastic recyclability and reuse is the best available solution to deal with plastic pollution. Following materials are deemed to be a better alternative to plastics.

  • Silicone
  • Glass
  • Papers
  • Bioplastic or Polylactic acids (PLA)

Though silicone is non-biodegradable, its use is supported by the fact that they are very durable and can be used any number of times. Hence, it is very unlikely to create waste pollution from it. With its proper use and recyclability, silicone can provide a better alternative to plastics.

Glasses have been used as storage containers and for many other purposes in place of plastics. However, the important advantage of using glass is that it is 100% recyclable with no downcycling. Their recyclability rate is also high making it one of the best alternatives to tough plastic.

We all know that paper is biodegradable. But, if you are worried about the cutting down of virgin forest, then there are other options such as  wood pulp obtained from bamboo plants which is quite easy to grow and matures in a few months. Bamboo is also known to absorb high amounts of carbon dioxide and keep our environment healthy.

Researchers have come up with many other alternatives to plastics. Single use bioplastics such as polylactic acids have been shown to have good biodegradability with industrial composting. They are made from naturally occurring renewable carbohydrate sources and hence do not cause any threat to our fossil reserves.

Steps taken by the Government to keep plastic waste within limits

For the past several years we are witnessing the changes in several policies and rules by the Government for controlling plastic pollution. Some of these rules that are implemented strictly are highlighted below:

  • Cleaning up water bodies by fishing for plastics.
  • Recycling plastic for making roads.
  • Enhancing proper collection of plastic wastes from each household. 
  • Providing funding to startups for a sustainable alternative to plastics.
  • Funding the research for plastic waste management. 
  • Some states banning single use plastics.

Conclusion

In this report we have discussed the question “is plastic biodegradable?” and included the different aspects and features that make plastic non-biodegradable. We have further highlighted the steps taken by our Government to susdie the negative effect of plastic on the environment and have summed up some of the best alternatives to plastic.

Frequently asked questions (FAQs): “Is plastic biodegradable?”

Is plastic biodegradable?

Plastic is not biodegradable as there is no natural process or enzymatic means by which plastic can be degraded. However, researchers are studying bacteria and fungi in marine environments that can cause plastic biodegradation. 

Why is plastic not biodegradable?

Plastic is made from repeated units of carbon based monomer. Their functionality is enhanced by the introduction of different functional groups that give the characteristic feature to the plastic. Due to this the biodegradation of plastic takes thousands of years to start. 

Can plastic form naturally?

The traditional plastics that are widely used today are synthetic plastics which means they are made from naturally available raw materials. These raw materials are treated at specific conditions to make plastic with specific molecular weight. 

Which plastics are non biodegradable?

Most of the traditional plastics like polyethylene, polystyrene, polyvinyl chloride etc. are non-biodegradable. They are formed from carbon bases with several functional groups. The chemical and molecular nature of plastic polymers makes it sturdy and difficult to break by natural means. 

How does plastic decompose?

Overtime, plastics are disintegrated into microplastics that end up in our food chain affecting our ecosystem. In ocean water these are usually withered and disintegrated by the marine environment. However, for some types of plastics, microorganisms cluster up on the polymer and make a biofilm.  

Is it OK to burn plastic?

No, it’s never a good solution to burn plastics as fumes from burning plastic contain many toxic elements such as dioxins, furans, mercury, and polychlorinated biphenyls. 

These toxic gasses cause severe health problems and some of them are potentially carcinogenic. Regular exposure to these fumes causes respiratory ailment and affects our immune system. 

Why is plastic a problem?

The main issue with the plastic is its non-biodegradability. With every use, these materials are piled up and pollute our environment. The problem also lies with managing plastic waste as tons of single use plastic products are thrashed away improperly or burnt causing irrecoverable damage to our health. 

References

Min, K., Cuiffi, J.D. & Mathers, R.T. Ranking environmental degradation trends of plastic marine debris based on physical properties and molecular structure. Nat Commun 11, 727 (2020). https://doi.org/10.1038/s41467-020-14538-z

https://www.worldwildlife.org/initiatives/plastics

Harmful effects of plastic on our health. https://www.indushealthplus.com/harmful-effects-of-plastic-on-health.html 

Jacquin Justine, Cheng Jingguang, Odobel Charlène, Pandin Caroline, Conan Pascal, Pujo-Pay Mireille, Barbe Valérie, Meistertzheim Anne-Leila, Ghiglione Jean-François., Microbial Ecotoxicology of Marine Plastic Debris: A Review on Colonization and Biodegradation by the “Plastisphere”. 2019., Frontiers in Microbiology, Volume 10, 865. 10.3389/fmicb.2019.00865  

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