Earth Day 2024: what do we know about microplastic pollution?

On April 22, millions of people around the world recognize Earth Day. Every year, Earth Day provides an opportunity for everyday people to recognize the importance of environmental conservation and take action through various events and local sustainability initiatives.

The theme of Earth Day 2024 is ‘Planet vs Plastics’ – a theme chosen to highlight the dangers of plastic pollution and to call for a dramatic reduction in plastic production over the next decade.

One aspect of plastic pollution that is receiving increasing attention is the issue of microplastics. These tiny pieces of plastic waste – less than 5 millimeters in diameter – can be formed by virtually any process involving plastic and have already spread to contaminate large parts of the world.

Research into microplastics and their potential threats to human health and the environment is still in its infancy. Here we highlight some of the latest developments in microplastics research, from the potential health impacts to the push for a plastic-free future.

How are microplastics formed and distributed?

Understanding the sources of microplastics and how they spread is an important area for environmental research.

“I think most people think that the source of microplastics is waste that breaks down – it’s not really highly biodegradable; it simply breaks down into smaller and smaller pieces as it is weathered by sunlight. But we also find that a lot of fibers are released from the synthetic clothing we wear,” Dr. Matthew Ross, assistant professor in the Department of Physical Sciences at MacEwan University, previously said. Technology networks.

Another often overlooked source of microplastics in the environment is car tires. As vehicles move, tiny specks of synthetic rubber polymers are shed from the tires as they rub against the road surface. These microparticles that cause tire wear can easily be washed off the road surface and released into the local environment when it rains.

“Stormwater runoff, which contains a mixture of sediment, chemical, organic and physical pollutants, is a critical route for flushing microplastics from urban environments during rainfall and into local aquatic habitats. But to date, our knowledge of the amount of microplastics in urban stormwater, particularly tire wear particles, is limited, as are the potential strategies we can use to minimize this source,” said Dr Shima Ziajahromi, researcher at the Australian Rivers Institute. .

In a recent article published in Environmental sciences and technologyZiajahromi and her team analyzed rainwater and sediment samples collected near constructed wetlands during rainstorms. They found that about 19 of the 20 microplastics collected were tire wear particles, at concentrations ranging from 2 to 59 particles per liter of water.

The high prevalence of these plastic microparticles is of great concern, according to researchers from the University of Exeter and the University of Plymouth. In their latest research, published in the Hazardous Materials Journalthe joint research team found that tire wear particles can also contain toxic organic chemicals that threaten the aquatic environment.

But it’s not just our rivers and ponds that are at risk; Research has shown that microplastics can also be transported over long distances via air currents.

Recent models from researchers at Cornell University suggest that flat microplastic fibers are carried furthest by these air currents. These flat fibers also appear to spend 450% more time in the lower atmosphere than previously calculated. Improved models, such as this new Cornell model, will help scientists better determine the sources of microplastic pollution in the air, the researchers say.

“We can now more accurately attribute the sources of microplastic particles that will ultimately be transported into the air,” said Qi Li, assistant professor in the Department of Civil and Environmental Engineering at Cornell University and senior author of the paper. “Knowing where they come from can help you come up with a better management plan and policy or regulation to reduce plastic waste.”

The damage caused by microplastics

Dietary sources of microplastics are also of particular interest to environmental researchers.

Bottled water is an important source of microplastics in food. A recent study found that 1 liter of bottled water contains an average of approximately 240,000 detectable plastic fragments.

If you are a tea drinker, you may also be exposed to microplastics from polyethylene terephthalate (PET) or nylon-based tea bags. According to a 2019 study, a single plastic tea bag can release up to 11.6 billion microplastics and 3.1 billion nanoplastics in one cup of tea. Another study published in 2021 also suggests that these types of microplastic particles released from tea bags could be amplified if the tea bag is microwaved.

Regardless of the source, once this microplastic enters your body, researchers want to know whether it poses any risks.

According to a new article in Environmental health perspectivesmicroplastics can migrate through the body in the intestines and digestive tract and find their way to kidney, liver and brain tissue.

The study, led by Dr. Eliseo Castillo, associate professor of gastroenterology and hepatology at the University of New Mexico School of Medicine, exposed mice to microplastic-contaminated drinking water for four weeks.

“Microplastics have emerged in recent decades
have been found in the ocean, in animals and plants, in tap water and in bottles
water. They seem to be everywhere,” Castillo said.

They found that the microplastics easily crossed the mouse’s intestinal barrier and infiltrated other tissues. The study also showed some evidence that the presence of microplastics could alter metabolic pathways in affected tissues.

“These mice were exposed for four weeks,” Castillo said. “Think about how that compares to humans, if we are exposed to it from birth to old age.”

On the way to a plastic-free world

In light of widespread microplastic contamination and ongoing research into the associated health effects, other research groups are hard at work exploring new ways to clean up this contamination.

Researchers at the University of Waterloo have developed a new technology that uses activated carbon, derived from thermosetting epoxy resin, to remove nanoplastics from water. According to the researchers, the method is 94% efficient and could also help give epoxy – a polymer that is normally not reusable or reprocessable – a second life.

“To end the plastic waste crisis and reduce the environmental impact of plastic production, we must implement a circular economy approach that takes into account every stage of the plastics process,” said study author Tizazu Mekonnen, professor of engineering at the University of Waterloo.

Others are investigating whether hydrogel materials could be the answer. In a 2024 article published in Nanoscale, researchers from the Indian Institute of Science have demonstrated a multi-layer hydrogel that can remove microplastics from water via adsorption before they are further broken down when exposed to UV light. This allows their hydrogel to be reused up to five times before also being upcycled to form useful carbon nanomaterials.

In addition to microplastic cleanup, many also believe it is important to develop more sustainable alternatives to traditional plastic. Researchers from the University of California San Diego and materials science company Algenesis recently reported in Scientific reports the creation of a bio-based thermoplastic polyurethane that is completely biodegradable in less than seven months, even at microplastic level.

“We are only now beginning to understand the implications of microplastics. We have only scratched the surface of knowing the environmental and health impacts,” said study author Michael Burkart, professor of chemistry and biochemistry at the University of California San Diego. “We try to find replacements for materials that already exist, and ensure that these replacements are biodegradable at the end of their life rather than ending up in the environment. That’s not easy.”