Microplastic is a Future Threat to the Environment and Human health -Nadira Islam
The use of plastic products has reached an unprecedented level in every sector of the world, including households and industries. According to recent research, the worldwide production of plastics was 367 million tonnes in 2020, half of which was produced in Asia. That is why the region is now known around the world as a hotspot for plastic pollution. Consequently, global emissions of carbon dioxide (excluding landfills and incineration sources) have accelerated because of plastic production (Plastics Europe, 2018; Statista, 2020). Microplastics are small pieces of plastic, less than 5 mm (0.2 inches) in length, that occur in the environment as a consequence of plastic pollution. It consists of carbon and hydrogen atoms bound together in polymer chains. Other chemicals, such as phthalates, poly brominated biphenyl ethers (PBDEs), and tetrabromobisphenol A (TBBPA), are typically also present in microplastics, and many of these chemical additives leach the out of plastics after entering the environment.
Microplastics are divided into two types: primary and secondary. Examples of primary microplastics include microbeads found in personal care products, plastic pellets (or nurdles) used in industrial manufacturing, and plastic fibers used in synthetic textiles (e.g., nylon). Primary microplastics enter the environment directly. Secondary microplastics form from the breakdown of larger plastics; this typically happens when larger plastics undergo weathering, through exposure to, for example, wave action, wind abrasion, and ultraviolet radiation from sunlight.
Microplastics are present in a variety of products, from cosmetics to synthetic clothing to plastic bags and bottles. They have been found in a variety of environments, including oceans and freshwater ecosystems. In oceans alone, annual plastic pollution, from all types of plastics, was estimated at 4 million to 14 million tons in the early 21st century. Microplastics also are a source of air pollution, occurring in dust and airborne fibrous particles. The presence of plastic particles has already been found in a variety of human food items such as commercially cultivated shrimp, fish, salt, flour, fruits, vegetables, beer, honey, milk, and snacks.
The Guardian published a report on 24 March 2022 that microplastic pollution has been detected in human blood for the first time, with scientists finding the tiny particles in almost 80% of the people tested. A recent study found that microplastics can latch onto the outer membranes of red blood cells and may limit their ability to transport oxygen. The particles have also been found in the placentas of pregnant women, and in pregnant rats, they pass rapidly through the lungs into the hearts, brains, and other organs of the fetuses.
In Bangladesh, extensive use of single-use plastics and the indiscriminate management of these in urban areas, accompanied by improperly managed landfills lacking waste separation procedures, have been reported as the primary and secondary sources of microplastics in agricultural soil. Bangladesh is the 10th worst country in waste management and dumps waste in the Bay of Bengal. In 2020, microplastics were found in marine fish and living creatures in the Bay of Bengal. The presence of various plastic debris in coastal and oceanic waterways and their toxic effects on marine animals have been documented in the Bay of Bengal.
The urban rivers in Bangladesh, certainly in the capital Dhaka, have already been out of use for the last 10 to 15 years. We no longer can use Dhaka’s main Buriganga River, which flows past the southwest outskirts of the capital city, because it can’t be purified due to the high amount of pollutants. Almost 80% of the pollutants in the City Rivers were plastics. Global food safety is affected by microplastic in indoor and outdoor environments where they can accumulate as microfibers (Dris et al, 2017). Microfibers from sludge accumulations and their transfer into the human body were shown by early research.
Recently, researchers from Jahangirnagar University have found microplastic contamination at an alarming level in five brands and two samples of non-branded sugar in the country. In this research, the amount is so high that around 10.2 tonnes of microplastics could enter the bodies of the entire population every year through sugar alone. There is not enough research throughout the world on the impact of microplastics on the human body, but they have done research on different animals before including birds and frogs and noticed that microplastics support other pollutants and act as a secondary vector. And, it is a serious threat to human health.
Microplastics are emerging environmental pollutants that have gained tremendous scientific interest in recent years. These micro pollutants are omnipresent both in the terrestrial and aquatic environments posing a deleterious threat to the ecosystem and biodiversity. Microplastics can become accumulated in the animal’s tissue through ingestion or inhalation. Uptake of microplastics exerts lethal and /or sub-lethal effects on aquatic life forms by causing false satiation, behavioural effects (abnormal swimming and lethargy), pathological stress, decreased predatory performance, reproductive complication, growth and developmental inhibition, histological changes in the intestines, oxidative stress, and liver metastasis. Microplastics are likewise known to cause energy disturbance, immune and neurotransmission dysfunction, neurotoxicity, and genotoxicity in aquatic biota. Microplastic exposure is also responsible for changes in the expression of key genes involved in different regulatory pathways.
Remediation of microplastics already in the environment is another key component of reducing microplastic pollution. Strategies under investigation included the use of microorganisms capable of breaking down synthetic microplastic polymers. Some bacterial and fungal species possess biodegradation capabilities, breaking down chemicals such as polystyrene, polyester polyurethane, and polyethylene. Such microorganisms potentially can be applied to sewage wastewater and other contaminated environments. There are a few possible strategies to combat ongoing microplastic pollution in the environment.
i. Source identification and quantification of upstream microplastics,
ii. Adoption of zero scale waste strategies,
iii. Pursue policy-driven extended producer responsibility (EPR) in the industrial production sector whereby a producer is responsible for the health, safety, environmental and social impacts of a product throughout its life cycle periods, and
iv. Development of innovative business solutions following green engineering, e.g. bio-based and biodegradable polymers.
Effective and sustainable bioremediation of plastics, as well as microplastics, requires the comprehensive characterization of the fate of these compounds in the environment to adopt the appropriate bioremediation strategy. Plastic debris often acts as floating substrates onto which some alien species like bacteria, algae, bryozoan, and mussels are found to colonize and become invasive. Biomonitoring tools (e.g. biosensors, bioassays, biomarkers) have incredible applicability in the risk assessment and toxicological study of emerging chemical pollutants such as microplastics in the ecosystem and biota.
Microplastic contamination is a global concern and this research field is rapidly evolving, especially in the last 10 years significant advances have been made concerning the understanding of the occurrence and impacts of microplastics. It is believed that the information gathered in this synthesis would provide a strong scientific foundation for microplastics research in Bangladesh that would aid in environmental conservation, technology development for plastic remediation and monitoring as well as strengthen the basis for educational campaigns and public awareness about the plastics and microplastics pollution; all of which will help in achieving a sustainable environment.
The author of this article is an Associate Editor (The Environment Review), Department of Environmental Science and Engineering, Jatiya Kabi Kazi Nazrul Islam University, Trishal, Mymensingh