Microplastics have been mapped deep within the tissue of living organisms in fine detail for the first time, in a new research study involving Kingston University London.

The study, published in Advanced Science, shows non-invasive methods can be used to detect microplastics deep in the living tissue of mice. Previously, this was possible only through dissection.

Researchers from Kingston University, University College London (UCL) and the University of Birmingham detected common microplastics such as polypropylene (used in food containers and coffee cups) and polyethylene (used in single-use plastic bags).

They used a novel technique called photoacoustic imaging, in which pulses of laser light are directed into tissue and absorbed by microplastics, which have a unique absorption fingerprint. Light absorption generates tiny high frequency sound waves, which are then picked up by ultrasound detectors to create a detailed map showing where microplastics are located within the body.

The study, led by Lecturer in Medical Imaging at UCL Medicine Dr Stephen Patrick, unlocks the potential to understand how microplastics travel around the human body and impact health. An image created using the technique was shortlisted for the Wellcome Photography Prize 2025 and was displayed at a public exhibition at the Francis Crick Institute.

This high-resolution method can detect individual microplastics as small as the width of a human hair, while also allowing researchers to track how particles move and accumulate in the body over periods of months rather than days – a timescale more relevant to long-term human exposure.

First author on the study and Senior Lecturer in Inorganic Chemistry at Kingston University Dr Joseph Bear shared ongoing developments of this new technology. "The versatility of the technique allows us to shed light on the behaviour of other plastics in the body. Surgical implants such as hernia meshes are a particular focus due to their frequent mechanical failure, side effects and need for replacement. We are following this up with further research that aims to improve patient outcomes and the safety of these devices."

Until now, researchers have generally needed to chemically label microplastics before tracking them inside animals – a process that can change how the particles behave and limits how realistically they can be studied. The new method developed at UCL instead detects the inbuilt optical signature of common plastics themselves, allowing researchers to non-invasively map and track microplastics deep inside living tissue over periods of months and at microscopic resolution.

Dr Patrick said the study was important with all humans encountering microplastics. “Everyone on earth is exposed to microplastics – they are found everywhere: in our food, drink, clothing and home furnishings. There is growing concern over their effects on human health, which until now has been difficult to study inside living tissue. Most existing methods rely on biopsies or analysis of tissue after dissection, which limits what researchers can observe over time.”

“We expect our new approach to detecting microplastics will open up new avenues of research into where these particles accumulate in the body, how long they persist, and whether they contribute to diseases affecting the brain, blood vessels and other organs.”

Dr Olumide Ogunlade, formerly of UCL Medical Physics and Bioengineering but now based at the University of Birmingham, was the lead physicist in the study. He said: “By showing that microplastics can be visualised inside living tissue without altering or destroying it, this work lays important groundwork for future studies. Since the photoacoustic signal is directly related to the amount of microplastic, our method could overcome the limitations of existing indirect methods of estimating microplastic accumulation. We anticipate it will ultimately help researchers link everyday exposure to microplastics with long‑term health effects, in a way that better reflects what happens in real life.”

In the experiments, the mice were given controlled amounts of microplastics (around half a milligram per experiment, roughly equal to half a grain of salt) by injection so the researchers could precisely track how the particles moved through living tissue over time. As with humans, the animals were also likely to already have low background levels of microplastics from food and drinking water.