The Frightening Journey of Microplastics from Oceans to Our Bodies

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icroplastics are plastics smaller than 5 mm. They have become an issue of concern in recent years due to their widespread presence and potential impact on the environment and human health. Like air pollution, microplastics pose a hidden threat that is not always immediately attributed to their toxic nature.

Despite our limited knowledge in this area, early studies are alarming about the potential harms of microplastics. These tiny plastic particles can damage human cells and have been compared to dangerous substances such as asbestos and lead, which were once considered beneficial until researchers discovered their harmful effects. Scientists are urging caution and action, as we cannot afford to wait for the unequivocal verification of all the possible unintended effects of conventional plastics.

Microplastics originate from various sources, including the decomposition of larger plastic waste into smaller fragments. Among them are microbeads, a specific category of microplastics, which are tiny pieces of polyethylene plastic that are added to personal care products such as detergents and toothpaste. These particles can easily bypass water filtration systems and end up in oceans and freshwaters, posing a serious threat to aquatic life.

Microbeads have been found in honey, sea salt, beer, tap water, sugar, and even dust. Their presence spans the globe, from Arctic snow to the Mariana Trench. Microplastics have also infiltrated unexpected places like the human respiratory tract and bloodstream, raising concerns about their potential impact on human health. Scientists have even detected microplastics on remote, uninhabited island beaches as well as in ice samples from Greenland and Antarctica, highlighting the global scale of the problem.

The plastic cycle

Around eight million tons of plastic waste enter the sea every year. Over time, the sun’s ultraviolet rays, the movement of ocean waves, and the presence of salt cause this plastic to break down into smaller and smaller fragments known as microplastics. Small marine organisms like zooplankton eat these microplastics. That is how they enter the food chain. Small fish eat the zooplankton, larger fish eat the small fish, and so on. Eventually, fish end up in our food and water ends up in our bottles. Microplastics are in everyday products like shampoos, soaps, toothpaste, and facial cleansers. They travel through sewage systems and rivers and eventually end up in the ocean. In addition, car tires shed microplastic particles, which is another pathway for their diffusion.

Polluting our bodies?

In March 2020, microplastic pollution was found in human blood for the first time. This revelation came about when scientists tested blood samples from 22 healthy anonymous adult donors and found plastic particles in nearly 80% of those tested. Of those samples, 17 had plastic particles.

Specifically, PET plastic—commonly used in beverage bottles—was detected in half of them, while a third of the donors had polystyrene in their blood, which is used for food and product packaging. In addition, a quarter of the blood samples contained polyethylene, the material used to make plastic shopping bags.

Another similar study showed that these tiny particles can stick to the outer membranes of red blood cells, which could impair their ability to carry oxygen efficiently. The scope of the problem extends beyond the bloodstream; microplastics have also entered the placentas of pregnant women. Experiments with pregnant rats have also shown that microplastics can rapidly cross the lungs and enter the heart, brain, and other organs of developing fetuses.

In a study published in 2022 in the multi-disciplinary natural science journal Science of the Total Environment, a significant pioneering achievement was announced: the detection of microplastics in the lung tissue of living humans. The tiny size of these plastic particles allows them to penetrate our bronchioles and become trapped in various sections of the airway branches.

Recently, microplastics have been detected in human heart tissue, raising new concerns about their impact on long-term health. A team of researchers from China made this discovery while examining tissue samples from 15 patients who had undergone heart surgery.

Although there is a possibility that exposure to microplastics might have occurred during the surgical procedure, medical experts point out that the presence of certain chemicals in the human body —such as acrylic, also known as Plexiglas—provides direct evidence of microplastics in patients before they have undergone heart surgery.

From crop to plastic harvest

The problem of microplastics extends to agricultural practices as well. Sewage sludge, a byproduct of wastewater treatment, is often repurposed as organic fertilizer in agriculture. This practice has led to European farmland becoming a considerable repository of microplastics. Estimates suggest that tens of thousands of tons of these particles contaminate European farmland each year.

In 2022, an analysis by the Environmental Working Group, a non-profit environmental organization, revealed that nearly 80,937 sq km of cultivated land in the United States had been contaminated by sewage sludge, carrying per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals.” These substances, commonly found in plastic products, defy environmental breakdown.

Catherine Wilson, an author and deputy director of the Hydro-environmental Research Center at Cardiff University, states that the magnitude of microplastics in agricultural lands might be underestimated. Additionally, microplastics can endure within soils for extended periods. Research by soil scientists from the University of Marburg in Germany found microplastics as deep as 90 cm below the surface of agricultural fields where sewage sludge had been deposited over three decades before.

Plastic odyssey

Another alarming fact is the migration of microplastics from initial sewage sludge deposition sites to aquatic environments. A study conducted in Ontario, Canada revealed that 99% of microplastics journey away from these sites to aquatic ecosystems. Before their aquatic journey, microplastics can liberate toxic chemicals into the soil, exacerbating environmental consequences.

Plastics, such as polyester, acrylic, and nylon, constitute approximately 60% of clothing materials. Yet, garments fashioned from these synthetics shed microplastics, termed “microfibers,” during washing and wear. A United Nations Environment Program (UNEP) report (2020) on the global textile value chain indicates that about 9% of annual microplastic emissions result from clothing and textiles.

Experts suggest elongating garment lifespans and reducing washing frequency to curb emissions. When selecting new clothes, choosing sustainably produced natural materials can minimize the risk of unintended microplastic release, even at the cost of other environmental considerations.

Elisa Tonda, head of the Consumption and Production Unit at UNEP, stresses that involving all stakeholders is vital to usher the textile industry towards circularity and tackle microfiber emissions. Effective policies and an environment that fosters sustainable textile design are crucial, alongside brands assuming responsibility for end-of-life product management.