#574: Microplastics & Health: What Do We Know? – Prof. Ian Mudway

Introduction to this Episode

Theyʼre in our oceans, our air, our food, and now even in our bodies. Microplastics, once a distant environmental issue, have become a topic of urgent relevance in medicine, public health, and nutrition. The idea that tiny plastic particles are circulating through the food chain and accumulating in human tissues has sparked headlines, speculation, and concern. But how much of this fear is grounded in solid science? And how much is still unknown?

As the research into microplastics rapidly grows, so too does the confusion. Claims range from the plausible to the alarmist, yet the real picture is far more complex. What does current evidence actually tell us about the health implications of microplastic exposure? How do we weigh these emerging signals against the backdrop of other environmental threats we understand much better? And how should scientifically-minded practitioners think about this issue, especially when patients begin asking questions?

This is a conversation that calls for clarity, nuance, and a rigorous look at what we know versus what remains speculative. In this episode, Professor Ian Mudway, an environmental toxicologist, discusses the current scientific understanding of microplastics and human health.

About the Guest

Prof. Ian Mudway is Visiting Professor of Environmental Health at Gresham College and is a Senior Lecturer in Environmental Toxicology at Imperial College Londonʼs School of Public Health.

With over 25 years of experience, he has published extensively on particle toxicity in respiratory and systemic health contexts and advises both policymakers and public audiences.

While best known for air pollution research, Mudway has critically expanded his scope into microplastics, exploring their ubiquity in food, water, air, and human tissues (blood, placenta, lung, colon).

Useful Terminology for this Episode

• Microplastic – A plastic fragment or particle smaller than 5 millimeters in any dimension. These particles originate from the breakdown of larger plastic items (packaging, bottles, fibers, etc.) and are now pervasive in oceans, fresh water, soil, and air. Despite the term “micro,” 5 mm pieces are visible to the naked eye.
• Nanoplastic – An even smaller plastic particle, typically defined as under 1 micrometer (µm) in size. In toxicology, “nanoparticle” often implies <100 nanometers, but in the microplastic literature a looser <1 µm definition is used. Nanoplastics are small enough to potentially cross biological barriers (gut or lung lining) and enter the bloodstream, which is why they are being scrutinized for possible systemic effects.
• Exposome – A term referring to the totality of exposures an individual has over a lifetime and the impact of those exposures on health. It encompasses all environmental factors (chemicals, pollutants, diet, lifestyle factors, etc.) one encounters. In the context of this discussion, microplastics are one component of the exposome.
• PFAS (Per- and Polyfluoroalkyl Substances) – A class of synthetic chemicals often termed “forever chemicals” due to their persistence in the environment and the human body. PFAS are used in various industrial and consumer products (including some plastics) to impart properties like non-stick or water-resistant coatings. They are mentioned in this episode because they can be embedded in plastics or adsorbed onto microplastic particles, raising questions about whether microplastics might act as carriers for these toxic chemicals.
• Raman Spectroscopy – An analytical technique used to identify materials based on their molecular vibrations. In the context of microplastics research, Raman microscopy can detect and characterize individual plastic particles by their spectral signature. It allows scientists to confirm if a tiny particle is a polymer (plastic) and even determine the type of plastic.
• Bioaccumulation – The process by which substances (like pollutants or toxins) build up in an organism over time, often because they are absorbed faster than they are excreted.