Experts urge caution over microplastics in tissue claims and call for forensic approach to improve accuracy

Researchers are calling for urgent changes to how we study microplastics, following criticism of studies showing plastic particles in a range of human tissues.

Over 30 scientists from 20 institutions worldwide, led by Imperial College London and The University of Queensland and supported by the Minderoo Foundation, an Australian philanthropic organisation, are calling for improved standards for how microplastics are detected and reported in the human body.

The team of international experts highlight that the science of measuring these microplastics in the body is still a developing field. As a result, they warn that recent claims regarding their ubiquitous presence in human samples may be less certain than they appear.

In their paper, published today in the journal Environment & Health, they call for adoption of forensic science approach to bolster the methods used for the detection and measurement of plastics in human tissues, to improve the quality of evidence and help health professionals and policymakers make better decisions.

Human tissues and fluids contain a number of different natural substances that can interfere with measurements. Samples can easily be contaminated with plastic from the air, from clothing or from laboratory equipment. In some cases, commonly used techniques can also struggle to distinguish plastics from natural materials like fats or other biological components. In addition, several methods destroy the sample during testing, meaning that additional analysis cannot be performed to improve the confidence.

As a result, these challenges mean that not every reported “plastic particle” can be treated as definitive proof.
Professor Leon Barron, from Imperial College London’s School of Public Health, said: “Micro and nanoplastic pollution is a real global issue and it is important to understand their impacts. But when it comes the human body, tools are still only developing. Finding ‘something’ in the human body is not the same as proving it is plastic, and certainly not the same as proving it is harmful.” 

“Basic science gaps still exist and it is important to work together to reach consensus first. More transparency is needed about how confident scientists are in their test results so the public, health professionals and policymakers can make reliable decisions.”

Professor Kevin Thomas, from The University of Queensland, explained that no single measurement technique is currently good enough on its own to answer all the key questions: “Each method has strengths and blind spots. One of the best ways to build confidence is to use more than one kind of test on the same sample, particularly methods that work in different ways. When they all point to the same result, we can be far more confident we’re truly detecting plastic rather than something else.”

Professor Barron specifically points to learning from decades of progress in forensic science, and where this approach is standard practice. Forensic laboratories routinely combine several independent tests to identify tiny plastic fibres found at crime scenes, carefully control contamination, and clearly communicate how confident they are in their conclusions. Best-practice guidelines in forensics emphasise using multiple, complementary methods, documenting every step of the process, and explaining limitations to courts and investigators.

To help improve the reliability of results, the team has proposed a new framework that ranks laboratory methods according to the evidential value they hold. The most powerful methods, which can give detailed information about what a particle is made of and what it looks like offer far more value. Tools which provide only partial or indirect information are placed in lower categories, but some reports have relied only on these to make conclusions. 

For the strongest level of confidence, the scientists recommend using at least two of the most powerful, independent methods on the same sample wherever possible, supported by additional techniques, mirroring the practice followed by forensic laboratories in order to build a robust case from several types of evidence.

Professor Sarah Dunlop from the Minderoo Foundation emphasised that “We know that every day we eat, drink and breath in microplastics. Accurate measurement is mission critical to find out how far microplastics penetrate our bodies and impact human health.”

The researchers stress that this does not mean existing studies should be ignored. For example, even though scientists confidently know more about the chemicals contained within plastics, they argue that scientists should more clearly explain how certain or uncertain their findings are for solid particles detected in the body, and avoid presenting early or suggestive results as clear evidence. 

The team is calling for a wider international working group of scientists, clinicians, forensic experts and other specialists to agree common rules on how studies of micro- and nanoplastics in humans are designed, checked and reported. They believe that aligning standards with well-established frameworks from fields such as forensic analysis will help journal editors, regulators, funding bodies and the media judge which findings are strong enough to inform public health advice and policy.

The scientists emphasise that human exposure to micro- and nanoplastics is still likely and deserves serious attention, but they also underline that finding plastic in the body does not automatically mean it is causing harm. Much better, more consistent science is needed to reliably understand how much plastic can be found in the body, where it can be found, how long it remains, and whether it has meaningful effects on health.

Professor Barron said that getting this right is not just a technical issue but an ethical one: “There is huge public interest in microplastics and health, and that makes it even more important that we do not run ahead of the evidence. Reliable, carefully checked data must come first. Only then can we make sound decisions about how to protect people’s health.”

Professor Thomas added that building a solid evidence base now will pay off in the future: “People understandably want clear answers about microplastics and health. By being honest about what we know, what we suspect, and what we still don’t know, we can support smarter policies and avoid unnecessary fear. Strong, forensics-style standards today will lead to much stronger science tomorrow.”