Medical waste of COVID -19: Biodegradation of Plastic?

By C Dr Hemavathi

Mysuru, October 6:- Plastic consists of a good number of artificial or semi-synthetic organics. It can be soft and maybe prepared into solid objects of various shapes. Plastic is usually organic polymers of high molecular mass. The plastic garbage is also increasing on account of the growing population, new lifestyles and utilisation of goods and services. Modern lifestyle needs a disposable product like soda cans or water bottles, but the accumulation of these plastic products has caused immense plastic pollution in the world.

It is scientifically proved that plastic consists of harmful pollutants and poses severe threat to mankind and the environment. Plastic also creates havoc on natural environments, resulting in long-term problems for plants, animals, and people. There are certain long-term effects of plastic pollution which disturb the food chain in any ecosystem. It also impacts adversely water, land and air as a major source of pollution.

COVID-19 has necessitated the production of single-use PPE which has drastically ramped up during the pandemic. It is estimated that about 129 billion face masks and 65 billion gloves are used every month. These numbers are indeed staggering and warrant effective practical checks and balances by the stakeholders of environment and health. It is also observed that the pandemic is likely to divert the government’s attention away from green issues which matter most in the new millennium.

Practically, the quarantine economy has driven more people online, resulting in higher packaging waste from deliveries. Medical waste has increased these days and paved the way for biodegradation of plastic. The policymakers and people are required to do serious introspection about the changing role that plastic plays in all aspects of the economy. Efforts to tackle plastic pollution would improve ocean health, tackle climate change, support biodiversity and build sustainable livelihoods.

Plastic-munching gut microbes

One hint of hope has come from a group of organisms that scientists call plastivores which contentedly eat some of the most common plastics. It is found that over 50 species of microorganisms, mostly bacteria and fungi would turn plastics into energy. Scientists have discovered several insect species that thrive on eating polyethylene, the primary plastic in single-use bags. Plastic has made a tremendous contribution in day to day lives of people in several fields such as medical, agricultural, packaging, household, piping and other aspects of daily use.

The plastic used in a household system like food cover packets, sachets, Styrofoam cups, glasses, etc., would create non-biodegradable plastic waste which turns into decomposable excreta by mealworms. It is highly appreciated since the worm in which the bacteria is present in its gut has the ability to digest the complex plastic waste into smaller organic excreta. People are also advised to use worms known as ‘Tenebriomolitor’ mealworm which has proved to be an efficient method of reducing plastic to some extent. The mealworm grows rapidly within a span of 3 months and it can be grown in most of the normal climate and natural condition. Mealworms are the larval form of the mealworm beetle which feeds on vegetation and dead insects and periodically moults.

Two species of waxworm, Galleria mellonella and Plodiainterpunctellaare are known for eating and digesting polyethene plastic. These waxworms metabolize polyethene plastic films into ethylene glycol. They are known as bee pests that invade beehives and live off the honeycomb which is widely used by the people. The structure of honeycomb wax actually consists of very long chains of carbon and hydrogen, molecules called hydrocarbons. These hydrocarbon chains are the same things that make up the fossil fuel-derived plastics used so ubiquitously by humans.

Waxworms are the caterpillar larvae of wax moths which belong to the snout moth family (Pyralidae). These two closely related species are commercially bred. Waxworms are medium-white caterpillars with black-tipped feet and small, black or brown heads. They live as nest parasites in bee colonies and eat cocoons, pollen and shed skins of bees and chew through beeswax. The beekeepers consider waxworms to be pests. An enzyme in the worms or the bacteria living in and on their bodies is known for effectively dissolving the plastic. Scientists have discovered that wax worms can eat plastic bags and reduce plastic pollution. The solution to plastic pollution needs to focus on producing less and recycling more.

(The writer is Associate Professor and Head, Department of Botany, Government First Grade College for Women, Mysuru)

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