Plastic Not-So-Fantastic: A One Health Approach to a Growing Crisis Open Access

The potential impact of microplastics on human health has captured public attention in recent times. From the countless newspaper articles documenting evidence of microplastics in the human body, to scaremongering among social media influencers touting a plastic-free lifestyle, it is clearly a subject matter causing a significant amount of anxiety for the general population. In Germany, consumers ranked microplastics as their number one health concern during a survey carried out in 2023. We can observe the impact in everyday life, with an increase in use of paper and metal straws, or people swapping their plastic Tupperware for glass. This growing awareness has set the stage for scientists from all fields to ask, how much do we really know about the plastic in our environment, and what is it doing to our bodies?

Plastic pollution is a problem that has been growing exponentially since the invention of plastics in the early 1900s . It was not until after World War II that this material became widespread. From 1950 to 2024, yearly plastic production rose from 2 million to 450 million metric tonnes, the majority of which has ended up in our environment. The durable nature of plastics, and their long-drawn decomposition, has allowed them to persist, with some geologists suggesting plastic may be the marker of a new geological era, The Plasticene.

Microplastics are defined as plastic particles less than 5 mm in size. Some have been specifically engineered to be that size, such as in building materials, beauty products or plastic production pellets. Others are plastic particles that were once parts of larger pieces of plastic waste that have been broken down into small, irregularly shaped particles that can circulate in the air, or be transported through the rivers and seas.

The cycle of plastics pollution is one that has been caused solely by humans, impacting our environment and the animals that live in it. However, it is becoming more and more clear that this pollution is directly impacting us too. As the total amount of plastic produced each year steadily increases, so too do the number of microplastics entering our ecosystems (Figure 1).

Microplastics are commonplace in agricultural settings, often being deposited from mulch films, compost or from the atmosphere. Thanks to strong hydrophobicity, and a large surface area, they can adsorb and attach to other environmental toxins, such as heavy metals or organic contaminants, further increasing these pollutants toxic capabilities. Microplastics that have settled into the topsoil can be transported through the soil by earthworms, as they ingest and egest these particles allowing them to move into deeper soil, and eventually into groundwater. This impacts not only the chemical makeup of the soil, but may also impact the growth rates and lifespan of the earthworms they’re hitching a ride on.

From the soil, microplastics can make their way into crops, often having detrimental consequences. In wheat crops, microplastics can impact root vitality, leading to an impairment in growth. Something similar has been observed in a variety of fruits and vegetables after microplastics exposure; they caused cell wall deformation and a reduction in root biomass in carrots, inhibition of growth in cucumbers and a reduction in the total number and weight of strawberries. Crops containing microplastics go on to be harvested for human consumption, contaminating the food chain. Domestic farm animals also end up consuming these tiny particles, either from foraging in the polluted soil or from contaminated meal. In a laboratory setting, this disrupts animals' gut microbiome and can damage their internal organs, causing liver inflammation and impeding their ability to gain weight. Wild animals, for example, common garden birds like blackbirds or thrushes, often suffer a similar fate as a result of microplastic ingestion. Plastics have become so ecologically ingrained that ornithologists have started using plastics found in birds’ nests to date the settlement, like rings on a tree. A 30-year-old coot nest was discovered and dated in Amsterdam. The outer layers contained face masks from the pandemic, and the innermost layer contained a wrapper from a Mars bar with ads for the 1994 FIFA world cup.

The marine environment is perhaps the most well studied in this context, and the impacts of microplastics on this biome are devastating and far reaching. The “Great Pacific Garbage Patch” may be the perfect example of this, giving a frame of reference for the scale of this problem. Stretching from the west coast of North America to Japan, this plastic island contains an estimated 1.8 billion pieces of plastic and is three times the size of France (Figure 2). The constant agitation of these plastics by currents means most of these plastics are being broken down into microplastics. This has created a plastics stew with a surface area of approximately 1.6 million square kilometers. In total, there are an estimated 5 trillion plastic particles floating throughout the oceans.

Given the state of our seas, it is no wonder that this has begun to impact the creatures living there. Plastic particles can be found in sea turtles, resulting in the premature death of an already endangered species. They are inside many fish species all over the planet, where they are known to cause acute cellular toxicity and infertility. In addition, plastic particles accumulate in these fish, allowing them to enter our food chain, proof of which can be seen in studies showing the presence of microplastics in seafood.

These plastics are clearly toxic to both the environment and the animals in it, but as they become ingrained in these ecosystems, they now have an easy route of entry into the human body.

Microplastics have been found in a multitude of human organs. There is evidence showing them in the lungs, heart, brain, gut, placenta, liver, gallbladder and blood. Recently, investigations have shifted away from what tissues we can find them in, to what it is they’re getting up to in those tissues.

There are a variety of ways in which microplastics can get into the human body in the first place. They can enter via the oral route, by eating contaminated food, using plastic containers or from the millions of microplastics released from an individual teabag. Even our drinking water is known to contain microplastic particles, with estimates ranging from 6 to 100 microplastic particles per litre. The air we breathe contains microplastic particles, allowing for entry by inhalation. These can come from fibres from clothes, carpets or other soft furnishings, or from tyres being worn down on the road. Microplastics are at their highest density in urban areas and indoors. Air conditioning is also known to agitate their movement around rooms, meaning office buildings may be a particular hotspot.

What has become clear is that once they get in, these tiny particles have the ability to amass within tissues and cause an abundance of different problems. In a model of the blood–brain barrier, microplastics changed the morphology, increasing permeability. The presence of microplastics in the brain also increases the release of inflammatory cytokines, such as TNF-α and IL-1β, leading to neuronal damage.

Microplastics have been found throughout the heart and in the surrounding veins and arteries. One study screened heart tissue for microplastics before patients underwent cardiac surgery and found evidence of plastic in every single sample. Another study looking at microplastics in atheromas showed that major health events, such as stroke, non-fatal heart attack or death, occurred in 20% of patients with plastic present in their heart tissue, compared with 7.5% of patients without detectable plastic particles. Plastic particles have also been linked to the formation of lipid-rich foamy macrophages, an important cell in the progression of atherosclerosis.

Inhalation of plastic particles has also caused issues, with many workers who are exposed to occupational levels of microplastics within industry settings reporting respiratory symptoms and disease. It has been suggested that if particles are small enough, they may have the ability to reach the bronchial-alveolar regions of the lungs, and that the tiniest of particles may be able to diffuse through the alveoli into the bloodstream. The presence of these plastics in the lungs increases oxidative stress and inflammation, aggravating lung conditions such as asthma or chronic obstructive pulmonary disease (COPD).

These examples provide a small insight into the effect plastics are having on our bodies, but it is far from the full picture. Many other studies demonstrate detrimental effects in other tissues. However, further research is still needed to untangle the mechanisms that allow microplastics to cause so much damage.

The WHO has defined the One Health approach as an “integrated, unifying approach to balance and optimize the health of people, animals and the environment”. It highlights the need for a multidisciplinary response to global threats, where experts in their fields work not only with each other but also with those with legislative power in order to make a far reaching impact. Each facet of the microplastics problem is interdependent, so an interdisciplinary approach will be required to effectively address this growing issue (Figure 3).

At the moment, research has been restricted to collaboration within each individual field. Many biochemists and immunologists have been investigating how microplastics may impact human cells. So far, this research has mostly focused on perfectly spherical microplastic beads. While some argue this is a good place to begin, others say they have no application to real-world scenarios, where we know these plastic particles are made up of irregular shapes and sizes. Environmental scientists have already developed creative ways to make these irregularly shaped particles by cryomilling, chemically weathering and exposure to UV radiation. It is already known that the shape and size of microplastics impacts how toxic they are to cells. A transdisciplinary approach could allow us to answer the questions of why and how this happens.

Much of the knowledge needed to dig deep into research of how microplastics are impacting human health and the environment already exists. What could be improved upon are the collaborative efforts across disciplines to tackle this issue. We must acknowledge what Prata et al. previously referred to as “a lack of scientific maturity” in this field. The term microplastic has only existed since 2004, so the fact that a transdisciplinary network does not yet exist is really no surprise.

And yet, a multidisciplinary approach alone is not likely to aid this problem. Collaboration between experts in their fields and those with legislative power may even be more important. The current UN proposal on the restriction of plastic usage has been in talks since March 2022. Since this time, an estimated 65 million tonnes of plastic has been dumped into the environment, and still no treaty has been agreed upon. It must be acknowledged that plastic has become somewhat of a necessity. It was essential in keeping us safe day-to-day during the COVID-19 pandemic; it greatly increases food security by increasing shelf-life and is hugely important in the prevention of nosocomial infections in hospitals. It is no longer possible to live in a plastic-free world. The best way forward is to open up clear and effective dialogue between politicians, activists, scientists and the general public. This ensures that decisions being made are informed by science, that the most critical information is amplified by activists and that the public are receptive to, and engaged in, research-based evidence. To achieve this, there is a need for regular forums, public discussions, and more transparent media and social media coverage on this topic.

By adopting these collective efforts, we can hope to strike a balance between necessity and sustainability. In doing so, we might ensure that future generations inherit a world where plastic is managed responsibly, rather than left to pile up unchecked.

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• Hiemstra, A. F., Gravendeel, B., & Schilthuizen, M. (2025). Birds documenting the Anthropocene: Stratigraphy of plastic in urban bird nests. Ecology, 106(2), e70010.

• https://education.nationalgeographic.org/resource/great-pacific-garbage-patch/

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Ailbhe Herity is a PhD Researcher in the Department of Clinical and Experimental Medicine at Brighton and Sussex Medical School, where her research explores the immune system’s response to microplastics within the human body. Her research leverages experimental immunological profiling to identify environmentally driven alterations in immune function. Her broader research interests include immunology, environmental health and the biological impacts of day-to-day exposures on the immune system. Prior to joining BSMS, Ailbhe completed an MSc by research and a BA in Immunology at the Trinity College Dublin School of Biochemistry and Immunology. Her MSc work focused on the effects of psychosocial stress on the immune system, with a particular emphasis on premature ageing among people experiencing homelessness in Dublin. BlueSky: @ailbheherity.bsky.social. Email: [email protected].