How harmful microplastics are finding their way into the human body
Earlier studies showed presence of microplastics in grains, vegetables grown using fertilisers; latest research reveals that they can invade food chain through leafy vegetables, usually considered safe
Microplastics are entering the human food chain after being directly absorbed by plants from the air, a recent research paper published in the UK-based journal Nature has revealed. Earlier studies have shown that microplastics enter the body via food grains and vegetables that are cultivated using fertiliser and chemicals. The latest revelation has now posed a question mark on the consumption of leafy vegetables, which are widely considered healthy.
Entry path
The research shows that microplastics present in the air are being absorbed through the leaves of the plants and get accumulated there. They ultimately reach the food chain when consumed by humans.
The study revealed that microplastics can travel through the plant’s water and nutrient transport systems to reach other tissues. The size of the microplastics ranges from less than 1 micrometre up to 5 millimetres.
The research was conducted by scientists from Nankai University’s College of Environmental Science and Engineering, the University of Massachusetts Amherst, the Chinese Academy of Sciences’ Research Center for Eco-Environmental Sciences, Northeastern University, and the Beijing Academy of Agriculture and Forestry Sciences.
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Absorbed by roots
The study pointed out that microplastics get absorbed more quickly in outdoor environments where its concentration is higher. Its concentration in the plants depends on the concentration of microplastics in the air.
“The way the nutrients are being absorbed by the plants through the roots, the microplastics are also being absorbed through soil. Once upon a time, ash used to be treated as manure and used for the plants, but it is found that burning the waste with plastics leads to the release of heavy metals, chemical,s and colouring agents to the soil,” Tamil Nadu-based environmental writer and activist Geo Damin told The Federal.
“It's not just plants, even humans are directly inhaling microplastics through open burning places, food packed in plastic covers, juices in plastic bottles, and others, and those living near incinerators. No matter the quality of plastics, humans are directly consuming microplastics," added Damin.
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‘Consumption can be controlled’
Evan as the quantification of the overall consumption of microplastics from plants is not feasible, the global study showed that on average, people could be ingesting approximately 5 grams of microplastics every week, equivalent to the weight of a credit card.
Damin said that there are industries that produce microplastics intentionally and others that produce them as a disintegrated product, adding that microplastics are deliberately added to products such as plastic crayons and makeup products.
“On the other hand, there are products that leach plastic to the environment upon disintegration of the plastic products unintentionally, such as plastic bottles, cups, plates, and others. We cannot completely stop the manufacturing of these products, given the economic impact; however, there can be only control on the consumption of these products on an individual level," he says.
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Effects on human body
Moreover, the widespread practice of civic bodies burning plastic waste should also be reconsidered, as microplastics could reach the leaves of the plants and crops through air.
A 2024 study on the impact of ‘Microplastics and Nanoplastics on Human Health’ published in the National Library of Medicine stated that humans are exposed to microplastics through ingestion, inhalation, and dermal contact.
"They pass through the cell membrane and enter the cytoplasm and even the mitochondria. Microplastics appear to cause damage by slowly leaking their chemical constituents into surrounding tissues," it added.
Microplastics can penetrate the intestinal, blood, blood-brain, and placental barriers. Microplastics have already been detected throughout the body: in the placenta, meconium, breast milk, lung, intestine, liver, kidney, heart, and cardiovascular system, blood, urine, and cerebrovascular tissue, affecting all metabolic functions.
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What happens to disposed plastic?
Dr Nanda Kumar, senior consultant of General Medicine at SRM Global Hospitals says that the plastic utilisation is increasing day by day. Pointing out the large-scale use of plastic furniture and household utensils, he explained what happens to the plastic after it’s disposed of.
“With time, these particles get shredded due to the effect of ultraviolet rays and they will be converted into microparticles. These microparticles contaminate the water sources as well as the soil and the habitats involving soil and water. The plants are directly impacted due to the same, and there can be absorption of plastics from the environment in the plants," he added.
Last year, a Tamil Nadu-based research centre named SDMRI also confirmed the presence of microplastics in seafood in the state. Doctors warn that improper waste disposal is turning out to be a growing health hazard. Experts raise concern over the risk of heart attack, stroke, neurological disorders, and non-communicable diseases due to the presence of microplastics in the food cycle.
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Danger of cardiovascular diseases
Doctors say that microplastics were detected in excised carotid artery plaques, which can cause cardiovascular issues and obstruction in the brain can lead to neurological problems as well. Inhaled particles might irritate and damage the lungs, akin to the damage caused by other particulate matter.
"The consumption of plant-based food or seafood leads to the exposure to different types of micro and nanoparticles that can cause mechanical obstruction and deposit of microplastics in the vital organs can also cause health problems. Moreover, colours and chemicals present in plastics can be indirectly consumed by humans and animals. These chemicals can be carcinogenic, and microplastics contamination in the human body can cause several other health issues, such as non-communicable diseases, such as diabetes, hypertension and thyroid. There is evidence supporting the direct relation of plastic causing thyroid inflammation and risks of other health problems," added Dr Nanda Kumar.
Doctors also say that the microplastics can cause inflammatory diseases, irritable bowel syndrome, and an imbalance of gut microbiome. Microplastics also impact the immune system as immune cells seem to die faster due to engulfing microplastic particles.
Impact on immune system
Dr Prasad Eswaran, senior consultant of Medical Oncology at Apollo Proton Cancer Centre said that several studies have revealed that microplastics are present in a micromolar or a nanomolar concentration even in blood circulation.
"When microplastics are being absorbed in our food, they ultimately reach the internal tissues. It's already concerning that we are inhaling it from the air and it is absorbed by plants, which takes it to our daily food. Studies have revealed that fruits and vegetables are either exposed to the soil or have layers of wax on the surface, as in the case of apples. Over few years, the gastrointestinal system has been exposed to plastics, which leads to a lot of abdominal issues, inflammation, irritation in the windpipe pipe and also impacts the colon. The microplastics contain chemicals that are benzene products, which can be cancer-causing elements,” he added.
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As for the impact of chemicals on the immune system, he said that the chemicals inside the body are eliminated by the immune system but overexposure of microplastics can be overwhelming for the body.
"Over a period of 10-15 years, the body starts accepting these chemicals as a cell of the body or a part of the body. If the microplastics are going to be consumed as everyday food, the immune system would fail to identify toxins. It fails to detect any changes that happen because of the chemical agent and this failure in the immune system leads to different kinds of health problems including cardiac issues, respiratory problems, skin issues, neurological problems and inflammatory disorders, etc." he added.
FSSAI initiative
Despite the six-year ban, the use of single-use plastics continues in the state. Moreover, there are about 15,000 plastic products that are in use in the market for packaging but only about 15-20 of them are banned. Though called safe, experts say that all types of plastic leach into the environment.
Meanwhile, the Food Safety and Standards Authority of India (FSSAI) has launched a project to tackle microplastic contamination in food and develop methods to detect it in August last year. FSSAI is developing standard protocols for analysis of micro/nano-plastic, conduct intra- and inter-laboratory comparisons, and generating data on microplastic exposure levels among consumers.
A designated food safety officer from Tamil Nadu said that the ban on the use of single-use plastics is being implemented, but several vendors continue to violate the regulations for food packaging and processing.
"The department is undertaking inspections and imposing fines against violators, but we cannot control the use of microplastics in domestic settings. For the food and hospitality sector, we ensure that only permitted plastic is allowed to be used. When microplastics directly enter through plants, it will be very difficult to control the consumption in humans".
