Plastic pollution is the extraction of plastics by the environment which in turn has adverse effects on wildlife, wildlife habitats, and even mankind. Plastic contamination depending on the size is classified into three categories: micro, meso andmacro. Regular use of plastics is increasing the level of plastic pollution.Most commercially used plastic products like polythene bags, cosmetic plastics and household plastics are not recycled. These take the form of waste from the environment. Human unconsciousness is the main cause of plastic pollution.
Plastic is a chemical that takes a long time to decompose in the environment or to be recycled in a factory. That is why it is termed as a waste material. Therefore, plastic waste has a long lasting harmful effect on the environment. Plant species, aquatic animals, and island animals in general are facing severe losses due to plastic waste. Plastic waste obstructs the habitat, food storage and food intake of these animals.
Not just plants or aquatic animals, humans are being directly and indirectly affected by plastic pollution. Plastic contamination is indirectly responsible for excess secretion of thyroid hormone. In the United States, 5 million tons of plastic products are used every year. At present, various initiatives have been taken to reduce the use of plastic products in different countries. Legal action is also being taken against the use of polythene bags in Bangladesh.
Two types of plastics are generally responsible for plastic contamination: microplastics or small plastics and macro-plastics. Plastic waste is also classified as primary or secondary. At the time of initial plastic collection, they remain in their original structural state. Examples are bottle caps, cigarette butts, and micro-waste. Plastic waste that is between 2 and 5mm in size is called micro-waste. Meso and macro waste can be converted into micro-waste by crushing. Micro-waste is commonly known as nurdle. Nurdle makes new plastic products, but because of their small size, they can adapt quickly to the environment.
Due to the small size of micro-waste, filter feeding organisms accept these. A 2004 study by Richard Thompson of Plymouth University found large amounts of micro-waste in seawater in Europe, America, Australia, and Antarctica. Thompson and his colleagues found broken pieces of plastic used for household and commercial purposes in the area's waters, some smaller than human hair. Macro waste is often found in seawater, which has a detrimental effect on marine life. Plastic waste is dispersed into the environment in different ways from the place of origin. Plastic waste is spreading in different ways due to ocean currents, wind speed and geographical diversity. Since plastic is a waste material, it stays in the environment until recycled after creation. Plastic waste is destroying the balance of the environment in various ways. Chlorinated plastics emit toxic chemicals that mix with groundwater and surface water. Then, as we absorb groundwater and surface water, it enters our food cycle. It takes 400 years to rot in the soil. Different types of microorganisms live in the soil which helps in breaking down plastic molecules. Among these microorganisms are Pseudomonas, Nylon-eating bacteria, Flavo bacteria etc. These bacteria break down the nylon molecule by secreting the enzyme "nylonase".
Methane gas is produced through the breakdown of plastics which is a type of greenhouse gas. It is responsible for global warming. According to a 2012 study, there are an estimated 165 million tons of plastic waste in the world's oceans. Nurdle is a type of manufactured plastic product used to make cargo ships. A large number of nurdles fall into the sea water. The amount of this plastic substance has been increasing year by year.
According to one estimate, more than 5 trillion plastics float in seawater. The amount of plastic in the ocean is more than stars in our Milky Way galaxy. More than 14 million tons of plastic is being deposited in the sea every year. Plastic pollution is the single biggest threat to marine life. Scientists have found large amounts of plastic waste in the stomachs of several marine species, such as sea turtles. Whenever this happens, the animals starve because the plastic waste shuts down their digestive system. Sea turtles usually feed on jellyfish, marine insects. Because jellyfish are shaped like plastic bags, turtles mistakenly eat plastic bags. This causes their esophagus to close and they die slowly as they are unable to take food.
Marine whales are even more affected. Large amounts of plastic have been found in the stomachs of marine whales. Plastic also found in the stomachs of small marine fish. Plastic pollution affects not only marine fish but also marine birds. Because of the inability to compare between plastic and fish floating in the ocean, birds accept plastic. Plastics usually emit toxic chemical polychlorinated biophenols. This toxic chemical damages various tissues of the body.When birds absorb plastic substances,polychlorinated biophenols emits into their stomachs. As a result, their body tissues destroyed, their immune system weakened and gradually the bird dies.
Plastic pollution has a huge impact on human health. Plastics are usually mixed with large amounts of chemical dyes. These dyes act as carcinogens and damage the endocrine glands. Countries around the world have taken steps to reduce plastic contamination. Some supermarkets have reduced exchanges through plastic bags and are using biodegradable materials. There are many advantages and disadvantages to using biodegradable plastics.
There is another type of degradable plastic that is not manufactured by biopolymers, as these are oil-based, and behave similarly to other conventional plastics. These plastics are made in such a way that they are easily corroded with the help of various additives. These additives, with the help of the sun's ultraviolet rays or other physical regulators, help them to decay faster. Although biodegradable and degradable plastics help prevent plastic contamination, it also has some limitations. One problem is that they do not erode very effectively in the natural environment. Oil-based plastics break down into smaller pieces, but they no longer decompose.
Up to 60 percent of the plastic medical materials used are incinerated in furnaces instead of landfills to reduce the spread of the disease. As a result, the amount of plastic waste from medical supplies has been greatly reduced. However, many studies have expressed concern about the gaseous emissions from incineration.Various organizations, such as the Environmental Protection Agency, often do not evaluate the safety of new chemicals until the negative aspects have been identified.
Once that chemical is suspected to be toxic, it is studied in terms of the human ideal dose. This human standard dose is the level of least harmful effect for humans. High doses are tested during this study to see if it has any detrimental effects on health. And if not, low doses are considered safe.Despite such a complex assessment process, various policies are adopted to reduce plastic pollution and its damage. Various policies are being implemented by the government to prevent the use of harmful chemicals in certain plastic products.
Md Arafat Rahman is a Columnist & Asst. Officer, Career & Professional Development Services Department, Southeast University.