By Dr Matthew Doré, palliative care consultant at Northern Ireland Hospice & Royal Victoria Hospital in Belfast. 

What is the new smoking? History teaches us there is likely something which we are doing right now, that one day we will look back at in abject horror. There is likely something which we have some current evidence about, which we urgently need to change.

I would suggest the thing we should be looking more into is the harm from microplastics, and their impact on health, symptoms and quality of life.

The laboratory (in vitro) tests are quite clear (1) that microplastics cause harm to human cells. Question is, is there a safe dose? There is a paucity in epidemiological studies to outline this at a population level and therefore as a consequence the ‘European Union Scientific Advice Mechanism’ in 2019 (2) states: “little is known with respect to the human health risks of nano- and microplastics, and what is known is surrounded by considerable uncertainty” and suggests “even though ‘high quality’ risk assessment is not yet feasible, action to reduce, prevent and mitigate pollution with microplastics is suggested to be needed.” The conclusion is stark in stating that “the poison is in the dose”.

However since then there has been a rapidly growing body of evidence that microplastics are likely causing harm at the current doses we are being exposed to.

An example: faecal microplastic concentration in inflammatory bowel disease patients (41.8 items/g dm) was significantly higher than that in healthy people (28.0 items/g dm) and the evidence indicates that a positive correlation exists between the concentration of faecal microplastics and the severity of inflammatory bowel disease (3). Or the potential effect of microplastics on asthma (in mice in this study (4) ), but extrapolates this with a review of the epidemiological studies, “These studies tend to show a greater prevalence of asthma in urban compared to rural populations. However, these studies have been unable to identify which specific characteristics of the urbanisation process may be responsible.” (5) Interestingly, one of the most significant contributors to microplastics is postulated to be tyres from cars and trucks (6). Dementia is another area in which there is minimal current information as this study highlights (7) outlining microplastics are stored in the brains of mammals and calls for urgent research.

And what about palliative care and the impacts that microplastics may have on the wellbeing and symptom-control of our patients? Patients who are now sometimes with our services for many years, rather than merely a few weeks. Can minimising microplastic ingestion and absorption contribute positively to well-being, even symptom control?

I repeat and echo the sentiment from the BMJ in 2017 (8): If anyone was looking for research I would suggest we should be measuring microplastics in every illness and disease process, clarify if there is any causal link and work to highlight this as a new and growing environmental risk.

• Danopoulos, E., Twiddy, M., West, R., & Rotchell, J. M. (2021). A rapid review and meta-regression analyses of the toxicological impacts of microplastic exposure in human cells. Journal of Hazardous Materials, 127861.
• SAPEA, A. (2019). Scientific Perspective on Microplastics in Nature and Society. Science Advice for Policy by European Academies, Berlin.
• Yan, Z., Liu, Y., Zhang, T., Zhang, F., Ren, H., & Zhang, Y. (2021). Analysis of Microplastics in Human Feces Reveals a Correlation between Fecal Microplastics and Inflammatory Bowel Disease Status. Environmental Science & Technology.
• Lu, K., Lai, K. P., Stoeger, T., Ji, S., Lin, Z., Lin, X., … & Wang, L. (2021). Detrimental effects of microplastic exposure on normal and asthmatic pulmonary physiology. Journal of Hazardous Materials, 416, 126069.
• Rodriguez, A., Brickley, E., Rodrigues, L., Normansell, R. A., Barreto, M., & Cooper, P. J. (2019). Urbanisation and asthma in low-income and middle-income countries: a systematic review of the urban–rural differences in asthma prevalence. Thorax, 74(11), 1020-1030.
• Kole, P. J., Löhr, A. J., Van Belleghem, F. G., & Ragas, A. M. (2017). Wear and tear of tyres: a stealthy source of microplastics in the environment. International journal of environmental research and public health, 14(10), 1265.
• Prüst, M., Meijer, J., & Westerink, R. H. (2020). The plastic brain: neurotoxicity of micro-and nanoplastics. Particle and fibre toxicology, 17, 1-16.
• Wright, S. L., & Kelly, F. J. (2017). Threat to human health from environmental plastics. BMJ, 358.