Brain Health in the Age of Plastic

By definition, plastic is “a loose term for describing materials that can be formed and moulded under heat and pressure.”¹ Natural substances, such as rubber, would fall under this definition, as well as modern plastics, which are mostly synthetic. Both are polymers, which are “…large molecules, consisting of a chain of repeating smaller molecules (monomers). The process of combining these monomers (e.g. ethylene gas) by heat and pressure is called polymerisation,” and this is how synthetic plastics are made.²

According to the Science Museum’s article “The Age of Plastic: From Parkesine to Pollution”, the first manufactured plastic was made in 1862, and this invention laid the groundwork for the first fully synthetic plastic to be created in 1907. Since then, our use of plastic has skyrocketed. Now, the immediate pros of synthetic plastics are starting to be overshadowed by the permanent cons that are resulting in consequences for the health of our planet and ourselves. 

Plastics Are Everywhere—and They’ve Stayed Everywhere

Affordable, strong, flexible, and heat-resistant, polyethylene (the world’s most abundant plastic) was first used in WWII to insulate radar cables before being brought to the consumer market to make shopping bags, Tupperware, and medical devices. Nylon and Teflon soon followed; then polystyrene food containers and PET (polyethylene terephthalate, a form of polyester) water bottles hit the market. So many different polymers have been made to make different plastics, which we’ve used across a wide array of products, affording us convenience, sanitary peace of mind, and so forth.

Plastic doesn’t decompose. It’s not biodegradable. Instead, it breaks down into small and smaller pieces over time, creating micro- and nanoplastics, which have found their way into our environments and bodies. While studies like this one have aimed to summarize the impacts of micro- and nanoplastics on human health, looking at our exposure and uptake of plastics from various sources, our understanding of the full impact is still limited and more research is needed to be done. Recently, new studies have started to unearth findings that these previous studies aimed to identify. 

Life Is Plastic—It’s Not Fantastic

While Barbie’s words may have rang true in the early days of plastic invention and use, the reality of a world reliant on and made of plastic is now affecting our health in, well, less than glamorous ways. One study conducted in 2023 explored short-term exposure to microplastics in young and old mice. The researchers, led by Jaime Ross, an assistant professor of biomedical and pharmaceutical sciences at the Ryan Institute for Neuroscience, “…not only found that the [plastic] particles induced cognitive changes, but they were also able to cross the highly protective brain blood barrier.”³ The blood-brain barrier, which is meant to protect the body from pathogens and other harmful substances, has not been effective in keeping plastic particles out. This finding raises concerns about the potential for microplastics to directly impact brain tissue and function, which could lead to potential neurological impacts.

Ross’ research team wanted to further assess the long-term effects of exposure to microplastics, how and/or if the body can deal with them, and if there is a difference in how males and females respond. The initial results “…found that in just three weeks of exposure to microplastics through drinking water, the particles had not only begun to bioaccumulate in every organ, including the brain, but also that the study mice exhibited behaviors akin to dementia in humans.”⁴ Moreover, a decrease in glial fibrillary acidic protein (GFAP), was found. This protein supports many cell processes in the brain and, as Ross points out, “‘A decrease in GFAP has been associated with early stages of some neurodegenerative diseases, including mouse models of Alzheimer’s disease, as well as depression….’”⁵

Plastic and the Brain

More recent studies have revealed concerning findings about microplastics and their potential impact on brain health. A 2024 preprint reports researchers having detected microplastics in human brain tissue. The study found that brain samples contained significantly higher concentrations of microplastics compared to other organs like the liver and kidneys.⁶ In fact, the study also found that the amount of microplastics in brain samples increased by about 50% between 2016 and 2024—likely reflecting rising environmental plastic pollution and increased human exposure—and brain samples collected measured about 0.5% plastic by weight on average.⁷ 

MNPs Mechanisms of Damage

Laboratory experiments suggest microplastics may increase brain inflammation and cell damage, alter gene expression, and change brain structure.⁸ Furthermore, researchers have identified several ways microplastics may contribute to neurodegenerative diseases. Firstly, microplastics can promote inflammation in the brain, potentially aggravating conditions like Alzheimer’s.⁹ Along with neuroinflammation, certain types of nanoplastics, such as polystyrene, can cause the alpha-synuclein protein to accumulate abnormally, which is associated with Parkinson’s disease and other types of dementia.¹⁰ Nanoplastics may also interfere with the brain’s ability to clear protein aggregates, further contributing to neurodegenerative processes.¹¹ Finally, exposure to MNPs is known to cause endocrine disruption. The disturbance caused by some plastic compounds, like bisphenols, can potentially impact brain function and accelerate the progression of Alzheimer’s disease.¹²

While research is starting to reveal concerning links between MNPs and neurodegenerative diseases, more research is needed to be done to fully understand the long-term impacts and specific mechanisms involved. In all these studies cited, scientists and researchers are calling for further studies on chronic exposure and the development of technologies to monitor plastic pollution in the human brain.

How to Protect Yourself from MNPs

Unfortunately, we can’t hop in a time machine and undo our invention of plastic (*sigh*). Protection from MNPs now all comes down to reducing our exposure to and use of plastic-containing products. Doing so will not only help us reduce our MNP load, but it will also encourage a lifestyle that hinges on reducing and reusing items that are not only better for the planet and us, but last longer too (which means saving money long-term). 

What We Ingest: When it comes to our diet, cooking practices, and food storage, we can do a lot to cut down on our plastic use and exposure. Cooking meals at home using whole-food ingredients instead of reaching for ultra-processed foods that come in plastic is a good first step, as several popular food products contain high levels of plastic according to this data on plastics in Bay Area foods shows. When preparing food, use a wooden, metal, or silicone cutting board instead of a plastic one. Cooking vessels and utensils matter too. Opt for stainless steel pots and pans; use wooden, stainless steel, or medical-grade silicone cooking utensils; and, when storing and reheating food, use glass or ceramic containers. Not only do all these items last longer but they’re reusable and won’t leach microplastics. 

Stop with the single-use plastic water bottles; stay hydrated using a reusable stainless steel or glass water bottle (if you do find yourself using a reusable plastic water bottle, at least ensure it’s BPA-free). Also, investing in a high-quality water filter that can remove microplastics can help reduce your exposure to MNPs. If you’re one to enjoy coffee or tea throughout the day, opt for loose-leaf over bags or pods, which often contain plastic. If you’re getting your beverages out and about, think about investing in a reusable to-go cup to help cut down your use of disposables, which may contain plastics.

Additional Plastic-Free Measures

What We Wear: Fashion-wise, opt for clothing made of natural fibers. Think cotton, wool, and linen, rather than synthetic materials, such as polyester (which can be a thermoplastic). When it comes to makeup, try to choose plastic-free cosmetics. Skincare products, particularly those that have microbeads for exfoliation, also contain plastics.

How We Clean: Regularly cleaning your living space by vacuuming, mopping, and dusting can help reduce household dust, which may contain microplastics. Investing in an air filter can also help eliminate these microplastics hanging out in your home. As building Biologist Dr. Nicole Bijlsma says: “If you don’t use a filter, your body becomes the filter.”

When it comes to cleaning your clothes, wash synthetic clothes in a laundry bag to help prevent them from leaching into the water supply, or use a filter to catch microfibers during washing. Also, washing synthetic clothes less frequently and at lower temperatures can help reduce the microplastic shedding that occurs, and, when drying clothes, consider air-drying when possible to reduce microfiber shedding in the dryer.

Finally, when it comes to your own personal hygiene, be mindful of the single-use plastic items you’re using, such as toothbrushes, razors, makeup applicators, and more.

Footnotes:

1. The Age of Plastic: From Parkesine to Pollution. Science Museum. (n.d.). https://www.sciencemuseum.org.uk/objects-and-stories/chemistry/age-plastic-parkesine-pollution.
2. See Footnote 1.
3. A new study investigates the impact of microplastics in the brain. George Anne Ryan Institute for Neuroscience. (2023, August 4). https://ryaninstitute.uri.edu/microplastics/.
4. See Footnote 3.
5. See Footnote 3.
6. Campen, M., Nihart, A., Garcia, M., Liu, R., Olewine, M., Castillo, E., Bleske, B., Scott, J., Howard, T., Gonzalez-Estrella, J., Adolphi, N., Gallego, D., & Hayek, E. E. (2024). Bioaccumulation of Microplastics in Decedent Human Brains Assessed by Pyrolysis Gas Chromatography-Mass Spectrometry. Research square, rs.3.rs-4345687. https://doi.org/10.21203/rs.3.rs-4345687/v1.
7. See Footnote 6.
8. Hellewell , S., Gorecki, A., & Sofield, C. (2024, September 8). Microplastics are in our brains. how worried should I be?. The Conversation. https://theconversation.com/microplastics-are-in-our-brains-how-worried-should-i-be-237401.
9. Wang, G., Lin, Y., & Shen, H. (2024). Exposure to Polystyrene Microplastics Promotes the Progression of Cognitive Impairment in Alzheimer’s Disease: Association with Induction of Microglial Pyroptosis. Molecular neurobiology, 61(2), 900–907. https://doi.org/10.1007/s12035-023-03625-z.
10. Pelc, C. (2023, November 17). Brain health: Nanoplastics linked to Parkinson’s disease and dementia. Medical News Today. https://www.medicalnewstoday.com/articles/parkinsons-dementia-how-nanoplatics-affect-protein-in-brain. 
11. See Footnote 10.
12. University of Kentucky Research. (2024, February 28). Chemicals in plastics could be a risk factor for Alzheimer’s. News | University of Kentucky Research. https://www.research.uky.edu/news/chemicals-plastics-could-be-risk-factor-alzheimers.