Microplastics and Human Health – Part 2: Health Risks and Scientific Findings
Microplastics in our bodies – What science tells us
This post, the second instalment of a three-part series, explores the health risks of microplastics, examining the latest scientific findings and their implications for human health. It builds on the insights from the November 2024 scientific outreach event, Microplastics and Human Health, where experts highlighted a pressing global issue: the pervasive presence of microplastics and their growing threat to human health.
In the previous post, we explored the nature of plastics and microplastics, as well as potential solutions. Today, we delve deeper into the health risks of microplastics and the scientific discoveries made so far.
(You can watch the panel here and here).
Health risks of microplastics: “The impact of micro- and nanoplastics on human health”
Prof. Claudio Fenizia, Professor of Immunology, University of Milan: “The Impact of Micro- and Nanoplastics on Human Health.” To understand the scale of the problem, let’s first examine how microplastics have become an inescapable part of our environment—and our bodies.
Plastic has become an indispensable part of modern life. It’s affordable and durable, features that make it ubiquitous. Today, it is nearly impossible to find an object that does not contain plastic. However, this convenience comes at a cost.
In the Western world, the average person uses approximately four single-use plastic packages daily. Over a year, this amounts to 1,500 packages per capita, equating to 90 kg of plastic waste. In 2020 alone, tens of millions of tonnes of plastic were produced globally, with an estimated 8 million tonnes entering the oceans annually. This plastic waste accumulates, forming massive garbage islands. The first such island was discovered a decade ago, and since then, these formations have increased tenfold every ten years. Today, there are around 20 such islands, covering roughly 1% of the Earth’s surface.
Plastic waste doesn’t just float on the ocean’s surface—it also sinks, settling on the seabed. This phenomenon has led geologists to propose naming this sedimentary layer as part of the Anthropocene, marking a geological era defined by significant human influence.
Beyond the oceans, microplastics have been detected in virtually every environment on Earth, from aquifers to remote regions untouched by human activity. They are even present in the air we breathe.
How microplastics are formed
Microplastics are generated through mechanical friction, such as the wear and tear of tyres on roads, the washing of polyester clothing, and the exposure of plastic to UV rays, and to heating or cooling. These processes break down larger plastic items into micro- and nanoparticles, which accumulate as part of polluting particulate matter (PM10 or PM2.5).
Also, the fragmentation of microplastics releases additives—chemicals added to plastics to achieve desired properties. Many of these additives are toxic, further exacerbating pollution. Additionally, the mixing of additives during plastic recycling raises questions about the true sustainability of recycling practices.
These are secondary microplastics, obtained by unwanted fragmentation of larger plastics. Instead, primary microplastics are those produced already in the size of a millimetre: fertilizers, detergents, paint, and cosmetics.
How microplastics enter the human body
Micro and nanoplastics enter our bodies through inhalation, ingestion, and absorption.
- Inhalation: they are present in the air, making inhalation unavoidable.
- Ingestion: they contaminate seafood, agricultural products (meat and vegetables), and even drinking water. They are also found in food packaging, especially when it degrades. Everyday items like toothbrushes, nail polish, and pens contribute to our ingestion of microplastics. Studies have detected microplastics in human intestines and faeces, with infants being the most exposed—their faeces contain 14 times more microplastics than those of adults.
- Absorption: Microplastics have been found in human lungs, blood, and even organs. They have been detected in atherosclerotic plaques, the brain, male genitalia, sperm, the placenta, and umbilical cords. While some findings, such as those in the brain, are still under scientific review, their presence in critical tissues is alarming.
While these studies demonstrate a correlation between microplastic exposure and disease, the exact mechanisms remain unclear.
Health risks of microplastics & scientific challenges in proving causality
In conclusion, the health risks of microplastics are a growing concern, with scientific findings highlighting their potential impact on human health.
Despite mounting evidence, establishing a definitive causal link between microplastics and specific health outcomes remains complex. Scientific research is time-consuming, expensive, and must account for numerous variables. However, the inflammatory effects of microplastics are well-documented, underscoring the need for caution.
In the meantime, raising awareness about plastic pollution and its potential health impacts is crucial. Education and informed action are our best tools for addressing this global challenge.
In the next instalment of this series, we will explore the impact of microplastics on the fashion industry. Stay tuned!
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