Health Citizens – European Research Institute

Microplastics in a Changing Climate

Microplastics in a Changing Climate: Environmental Drivers of Mental Health Risk

Microplastics (MPs) are small plastic particles smaller than 5 millimeters and, in some cases, smaller than 1 nanometer (nanoplastics). They exist in diverse morphologies, including fibers, fragments, pellets, and microbeads, and originate from the degradation of larger plastics present in consumer products, synthetic textiles, cosmetics, and industrial processes1. Predominant polymers include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyurethane (PU), polyacrylonitrile (PAN), polyamide (PA), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), and polyvinyl acetate (PVAc)2. 

Environmental factors, including wind, floods, UV radiation, ice, and acid precipitation, further accelerate the fragmentation of plastics into micro- and nanoplastics3. At the same time, the production, dispersal, and accumulation of these particles are closely intertwined with climate change. If, on the one hand, plastic production relies heavily on fossil fuels, generating greenhouse gas emissions during extraction and processing, thus contributing to global warming, on the other hand, rising temperatures, glacial melting, extreme weather events, and altered precipitation accelerate plastic fragmentation, transport, and deposition4.  This creates a feedback loop that further amplifies global warming. Moreover, while extreme meteorological phenomena, such as storms and cyclones, facilitate the deposition of larger microplastics from nearby urban sources, lighter and smaller particles are transported over long distances under dry conditions, forming persistent atmospheric and terrestrial reservoirs2,5. As a result, microplastics are now present in nearly all aqueous and terrestrial ecosystems, contaminating food and water systems, and raising concerns for food safety, water security, and chronic human exposure3. Single-use plastics constitute a substantial portion of this plastic burden, with global production projected to triple by 2060 under current policies and regulations3.

Human exposure occurs primarily through ingestion of contaminated food products such as seafood, salt, sugar, honey, and drinking water. For instance, 240 000 detectable micro- and nanoplastic particles have been found in a 1L plastic water bottle. In the same context, it is known that  microwaving food in plastic containers or using plastic teabags can release billions of nanoplastic particles6,7,8.  Additional exposure occurs through dermal contact, as well as through inhalation of airborne microplastics released from textiles, synthetic rubber tires, and plastic surfaces9. Indoor air exposure is particularly relevant in poorly ventilated spaces, where synthetic textiles, carpets, and plastic flooring release substantial microparticles10.

Once inhaled or ingested, micro- and nanoplastics can cross intestinal and pulmonary barriers, enter the bloodstream, and accumulate in organs such as the placenta, amniotic fluid, testes, liver, kidneys, spleen, joints, heart, and brain10. A recent autopsy-based study reported substantial microplastic accumulation in human brain tissue, with concentrations several-fold higher than in peripheral organs and increasing markedly over time11. These findings suggest that the brain may represent a preferential site of microplastic deposition.

Within neural tissues, they induce oxidative stress, neuroinflammation, mitochondrial dysfunction, and disruption of neurotransmitter systems, including dopamine, serotonin, glutamate, and acetylcholine signalling10. Once internalized, microplastics act not only as physical particles but also as carriers of endocrine-disrupting chemicals like bisphenols, phthalates, PFAS and heavy metals, consequently introducing additional neurotoxic burdens by interfering with dopamine, serotonin, and glutamate signaling12,13. 

Emerging evidence links these biological effects to adverse neuropsychiatric outcomes. Animal studies have demonstrated cognitive impairment, behavioural alterations, and neurodevelopmental deficits following microplastic exposure, while epidemiological data increasingly associate environmental microplastic burden with depressive symptoms and mood disorders14. Notably, higher exposure levels have been correlated with increased odds of depression in young adults, with apparent vulnerability related to gender and age. In dementia patients, microplastic concentrations in brain tissue appear substantially elevated compared with neurologically healthy individuals, suggesting a possible contribution to neurodegenerative processes14.

Recent research findings indicate that microplastics may also influence mental health indirectly through systemic pathways. Disruption of the gut microbiome, increased intestinal permeability, and chronic low-grade inflammation represent plausible mechanisms linking environmental exposure to altered mood and cognition via the gut–brain axis10.14. Prenatal exposure also raises concerns, as microplastics have been detected in human placentas, with potential implications for fetal neurodevelopment and long-term neuropsychiatric vulnerability10.

Within this framework, climate change acts as a powerful amplifier of neurotoxic risk. By accelerating microplastic production, fragmentation, transport, and environmental persistence, climate-driven processes increase the intensity, duration, and geographic reach of human exposure. Simultaneously, climate change itself constitutes a recognised stressor for mental health, contributing to anxiety, depression, and psychological distress. 

Together, these observations highlight a complex and tightly interconnected system in which climate change and microplastic pollution converge to threaten brain health. Understanding this connection represents a critical priority for environmental science, neuroscience, and public health. Integrated research approaches that combine climate modelling, exposure assessment, toxicology, and mental health epidemiology will be essential to elucidate causal pathways and to inform effective mitigation and prevention strategies.

References:

  1. Sridharan, S., Kumar, M., Singh, L., Bolan, N.S., Saha, M. (2021). Microplastics as an emerging source of particulate air pollution: A critical review. Journal of Hazardous Materials, Volume 418. doi: 10.1016/j.jhazmat.2021.126245.
  2. Conti, G.O., Rapisarda, P., Ferrante, M. (2024). Relationship between climate change and environmental microplastics: a one health vision for the platysphere health. One Health Adv. 2, 17 doi: 10.1186/s44280-024-00049-9.
  3. Global Plastics Outlook: Policy Scenarios to 2060 (2022). OECD Publishing.
  4. Zheng, Y., Hernando, M.D., Barceló, D., Wang, C., Li, H. (2025).  Climate change exacerbates microplastic pollution: Environmental behavior and human health risks. Current Opinion in Environmental Science & Health, Volume 45. doi: 10.1016/j.coesh.2025.100608.
  5. Rowlands, E., Galloway, T., Manno, C. (2021). A Polar outlook: Potential interactions of micro- and nano-plastic with other anthropogenic stressors. Sci Total Environ. 754:142379. doi: 10.1016/j.scitotenv.2020.142379.
  6. Qian, N., Gao, X., Lang, X., Deng, H., Bratu, T.M., Chen, Q., Stapleton, P., Yan, B., Min, W. (2024) Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. Proc Natl Acad Sci U S A. 121(3):e2300582121. doi: 10.1073/pnas.2300582121.
  7. Hussain, K.A., Romanova, S., Okur, I., Zhang, D., Kuebler, J., Huang, X., Wang, B., Fernandez-Ballester, L., Lu, Y., Schubert, M., Li, Y. (2023). Assessing the Release of Microplastics and Nanoplastics from Plastic Containers and Reusable Food Pouches: Implications for Human Health. Environ Sci Technol. 57(26):9782-9792. doi: 10.1021/acs.est.3c01942.
  8. Hernandez, L.M., Xu, E.G., Larsson, H.C.E., Tahara, R., Maisuria, V.B., Tufenkji, N. (2019). Plastic Teabags Release Billions of Microparticles and Nanoparticles into Tea. Environ Sci Technol. 53(21):12300-12310. doi: 10.1021/acs.est.9b02540.
  9. Prüst, M., Meijer, J., Westerink, R.H.S. (2020). The plastic brain: neurotoxicity of micro- and nanoplastics. Part Fibre Toxicol. 17(1):24. doi: 10.1186/s12989-020-00358-y.
  10. Elizabeth Ryznar, Elizabeth Haase, Margo Lauterbach (2024). The Plastics Crisis: A Neuropsychiatric Problem Hidden in Plain Sight. Psychiatric Times Vol 41, Issue 9. https://www.psychiatrictimes.com/view/the-plastics-crisis-a-neuropsychiatric-problem-hidden-in-plain-sight
  11. Nihart, A.J., Garcia, M.A., El Hayek, E., et al. (2025). Bioaccumulation of microplastics in decedent human brains. Nat Med 31, 1114–1119. https://doi.org/10.1038/s41591-024-03453-1.
  12. Ullah, S., Ahmad, S., Guo, X., Ullah, S., Ullah, S., Nabi, G., Wanghe, K (2023). A review of the endocrine disrupting effects of micro and nano plastic and their associated chemicals in mammals. Front Endocrinol (Lausanne). 13:1084236. doi: 10.3389/fendo.2022.1084236.
  13. Fang, S.J., Yin, Z.D., Li, L.F., Cai, Q., Zheng, P.F., Chen, L.Z. (2025). Overall effects of microplastics on brain. Front Toxicol. 7:1619096. doi: 10.3389/ftox.2025.1619096.
  14. Villotte, F. (2025, Sep 7). The Hidden Dangers of Microplastics and Mental Health. Brain Nutri. https://www.brain-nutri.com/post/the-impact-of-microplastics-on-mental-health-an-emerging-concern.