Amid recent scientific and media scrutiny of the results of some high-profile reports of microplastics in the human body, a team of researchers has put forward an approach to communicate levels of certainty in findings. Dr Richard Cross of the Environmental Pollution group at the UK Centre for Ecology & Hydrology, a co-author of that article, tell us more…
Wherever we look, it seems we can find microplastics. But to understand the risks that these tiny particles of plastic debris pose to wildlife (not to mention ourselves), we must have confidence in correctly measuring the amount that we are exposed to.
Not only this, but it is also important to understand where these particles, fragments and fibres reach in the bodies of wildlife and humans, so we can predict the risk that they pose to environmental and human health.
This is a major challenge for chemists across the globe, including at the UK Centre for Ecology & Hydrology; we are working hard to establish standard ways to isolate, detect and describe microplastics and nanoplastics in samples taken from the environment).
To understand the risks of micro and nanoplastics, it is important to know how much plastic the animal or organ within the body has been exposed to, which can then be related to an effect on the health of the individual. However, it is not always enough just to know the total number or mass of particles. Toxicity can be driven by their size, with smaller particles more likely to be ingested by animals and circulated around the body.
Multiple factors to consider
The shape may also increase the risk. For example, UKCEH research has shown that synthetic plastic fibres can be retained in the guts of worms, reducing the amount they excrete, which could, in the long term, affect the fitness of these creatures or have knock-on effects in the wider environment.
Different plastics are also produced with different chemical additives, some of which are known to be hazardous. There are so many factors to consider, it is not a surprise that no single scientific instrument can provide all this information in one go.
Because of this, many different ways of measuring microplastics in the environment and human tissues have been proposed. In the absence of a single standard method, some recent high-profile reports of microplastics in the human body have been challenged by scientists working in this field. It has therefore never been more important to communicate the confidence that we have, as scientists, in the results we report.
In a recent article, an international team of researchers, including myself, highlight the utility of implementing approaches from forensic scientists, who are faced with this very challenge day in, day out.
In some ways, it is obvious that there are lessons that can be learnt from the field of forensics. Watch any episode of Silent Witness, and you’ll be familiar with the idea that unequivocal identification of a single fibre from a jacket, found on the victim, can close a case. Having confidence that you have found this fibre, that you know where it came from, and how it got there, is after all, a very similar challenge faced in human and environmental toxicology when detecting microplastics!
Common language needed
The recommendations from our study draw on the idea that it is necessary to use more than one analytical technique to confirm that a particle is truly a microplastic, and that these techniques should be based on different measurement principles, to avoid the same biases or limitations across the two techniques.
By confirming the detection of microplastic particles with multiple independent techniques, the confidence in the results is increased and any remaining uncertainty can be communicated more effectively.
We propose criteria to define microplastic identification by different degrees of certainty, from “presumptive plastic containing particles”, through to “unequivocal identification of plastic particles”, which will allow researchers to use a common language when reporting detection of microplastics in humans and the environment.
This is an important step for researchers, to help review and combine the wealth of data that is being generated by the scientific community in new and meaningful ways. But this is not all. It is also hoped this will help the public to better understand the necessary uncertainties associated with any report of microplastics in the environment or in humans, and so avoid confusion and the risk of miscommunication in this important and ever-growing field of research.
Further information
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Thomas et al. 2026. Communicating Confidence in the Reliability of Micro- and Nanoplastic Identification in Human Health Studies. Environment & Health. DOI: 10.1021/envhealth.5c00671
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UKCEH microplastics factsheet.
