It is not just the toxic particulate matter, but over 1.1 lakh residents of Varanasi in Uttar Pradesh might also be breathing in significant amount of microplastics widely present in the city air. One of the first such evidences has emerged from a new study conducted by researchers from Banaras Hindu University (BHU).
The latest findings emerge at a time, when the country is gearing up to take the first step to phase out some single-use plastic items, starting July 1. It is well known, that a very small percentage of the sheer amount of plastic used is recycled, and most of it ends up in landfills. Since, plastic takes over thousands of years to degrade, it slowly fragments into smaller particles – microplastics (less than 5 mm) – that have profound detrimental consequences.
The researchers led by Dipika Pandey and Tirthankar Banerjee from BHU set out to identify and quantify these microplastics in the air, and found it in every sample of atmospheric airborne particulate matter and street dust samples that they collected from various sites across the city during April-June 2019.
These dust samples were also sieved using a 5-mm sieve and further physically identified by binocular microscopy, fluorescence microscopy, and scanning electron microscopy (SEM). Researchers from Uttarakhand’s Hemvati Nandan Bahuguna Garhwal University were also part of the study.
They identified tiny fragments of plastic of different size, shape, and varied colours — pink, yellow, green, red and even transparent which mostly goes undetected. While the street dust samples were dominated by fragments (42%), fibres (44%) were seen common in the suspended dust in the air.
Other than that, there were fragments (28%), films (22%), and spherical droplets (6%). While, most of these fibres come from clothes and textiles, films/fragments result from disposable plastic bags and thicker plastic products, researchers explain. A similar study done in Nagpur in 2020 also threw same trends.
“What we found was that most of these particles were less than 1 mm in size which makes them easy to inhale, and can perhaps cause inflammation in the lungs,” said Assistant Professor Tirthankar Banerjee from BHU’s Institute of Environment and Sustainable Development.
Studies done across the world have raised concerns over how fine microplastics present in the air can easily pass through respiratory defense system and reach deep in the bronchioles. Though, potential risk of such ingested airborne particles to the human body is not yet known completely, scientists highlight that these risk depends on many factors like particle size, adsorbed chemical, concentration, deposition, and clearance rate.
However, it is not just the plastic, but their ability to adsorb toxic chemicals on their surface because of their large surface area and hydrophobic property makes their impact worse, added Banerjee. “They can even act as a medium to carry pathogens or microorganisms to the lungs and possibly result in an infection to humans.”
Further examination showed that these micro plastics carried toxic inorganic contaminants like metallic elements on these microplastics, especially elements like aluminium, cadmium, magnesium, sodium, and silicon which get adsorbed on their surface. These elements may also be due to the presence of additives, plasticizer, stabilizers, pigments, and dye used in plastic manufacturing.
According to the study published in journal Environmental Science and Pollution Research, majority of the microplastics were primarily polypropylene, polystyrene, polyethylene, polyethylene terephthalate, polyester, and polyvinyl chloride types. Polyethylene (PE) was the commonly traced plastic, which could be due to the widespread use of various PE-made items such as toys, milk and shampoo bottles, pipes, packaging films, grocery bags, and other bags in our day-to-day life.
“Our study gives first such evidence on the presence of micro plastic particles in both suspended and settled dust in a typical urban city of northern India,” said Banerjee, highlighting the need for further research into their exact impacts on human health. “It is a major cause of concern, not just for the environment, but for human health. Their presence in air, water and soil has already presented a critical challenge. What we can probably do at present is act on their source – which is the single-use plastic.”
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