When it comes to microplastics and human health, science can’t afford to be sensationalist

The idea that our bodies might be riddled with microplastics is alarming. It captures public imagination and stokes real concern about the impacts of decades of rampant plastic pollution. But as scientists who study how tiny particles interact with biological systems, we feel compelled to say: the way this story has unfolded in the public domain - and even in some scientific publications - risks doing more harm than good.

There is no question that plastics dominate our environment. Micro- and nanoplastics - fragments of plastic smaller than a grain of sand - are now ubiquitous in air, food, water and likely in wildlife. Their presence in marine organisms and ecosystems has been proposed for years. Yet the leap from “microplastics exist in the environment” to “they are present in high concentrations in human organs and causing harm” is not currently supported by rigorous, reproducible science.

One widely publicised study - reporting what were described as alarming concentrations of microplastics in human brains - has since come under legitimate scientific scrutiny. Critics have highlighted a range of methodological concerns, including insufficient controls for contamination and analytical approaches that may mistake fat molecules (lipids) for polymer particles as both are based on chains of carbon atoms.

The importance of evidence-led research

Put bluntly: when the very tools we use to detect plastics can produce false positives - especially in fatty tissues like the brain - we must pause and reflect. This isn’t scepticism for its own sake. It is basic scientific due diligence. Without rigorous validation, we risk drawing conclusions not from data, but from noise.

As popularised by Carl Sagan, “extraordinary claims require extraordinary evidence.” When plastics are literally everywhere - in lab air, on equipment, on lab coats and indeed the very lab gloves we use in chemical labs are plastic - the risk of contamination is high. Unless experiments include and document procedural blanks, recovery tests, and other quality controls such as tests for interference, the scientific community cannot be certain that what has been measured is truly from the tissue and not from contamination or misidentification.

This is not merely an academic concern. Science informs policy, public health advice, and public perception. If flawed studies generate headlines about plastic “embedded” in brains or placentas, the public will understandably be very unsettled. Yet if those headlines are based on uncertain data, they undermine trust in research overall - especially if subsequent work fails to replicate the results.

We are at a pivotal moment. The field of micro- and nanoplastics research is young and exciting, but it also suffers from something familiar in emerging disciplines: a shortage of standardised methods and a hunger to publish dramatic results quickly. In other fields - from climate science to virology - rushed or poorly controlled research has taught the scientific community and the public painful lessons about premature conclusions.

We must not repeat those mistakes here. Rigorous, transparent science builds credibility. That includes openly sharing data, standardising protocols across laboratories and developing certified reference materials - tools that allow different groups to verify one another’s findings. Without these foundations, even the most striking discovery remains scientifically fragile.

Understanding the real impact of microplastics

This does not mean that microplastics pose no risk to human health. We do not dispute that humans are exposed to these particles through food, drink, inhalation and possibly skin contact. But exposure does not automatically equate to harm. The concentration, the size of the particles, how they interact with cells and tissues, and the body’s ability to clear or sequester them, all remain poorly understood.

The challenge before us is to separate signal from noise. We must invest in better analytical methods and apply those we have within their limits of detection and with appropriate checks for interference through robust study designs. We must also communicate uncertainty honestly, both within science and to the public. The alternative is a landscape in which hyperbolic claims fuel fear or worse, create openings for vested interests to dismiss valid environmental health concerns altogether.

Ultimately, the goal of scientific research is not to generate the most read headline, but to deliver the most reliable understanding – to produce extraordinarily scientifically robust evidence. If microplastics truly infiltrate human tissues at meaningful levels, we will uncover that truth with careful, collaborative effort. And only then can we responsibly discuss the implications for human health and policy.

Read the full Matters Arising article published in Nature Medicine.