There are Microplastics in Our Brains: A Possible Factor in Neurotoxicity

It is safe to think of our bodies as a microcosm of planet earth. As our planet becomes more inundated with industrial pollutants of all sorts, so do our bodies. It is an unfortunate and detrimental parallel. Over 500 million metric tons of plastics, comprised of over 16,000 different chemicals, are produced annually according to the Plastic Health Council. This council does not represent the plastic industry but rather is an organization of scientists seeking to preserve and disseminate research on plastics, human health and the environment. It may come as no surprise that microplastics, the broken down remains of plastics manufactured as goods, have been found in the heart, liver, lungs, blood, semen, placenta, nasal passages and the intestines. But more alarming is that microplastics have now been found in brain tissue.

Microplastics in our brain

A group of Brazilian researchers supposed that, since the air we breathe is filled with micro fragments of plastics that have been found in nasal passages, that these microplastics could possibly enter the brain through the olfactory bulb. The olfactory bulb is in anatomic proximity to the nasal passage. To test their hypothesis, they dissected the olfactory bulbs of eighteen deceased adults. It is the stuff of autopsies and pathology laboratories so I will move straight to the results. They found sixteen chemically difference plastic particles and fibers. They described the particles as fragments mostly, some spherical in shape, along with fibers. The sizes of microplastics found were up to about a quarter the width of a human hair and the fibers found were slightly smaller than that. The presence of microplastics in the brain may just be the tip of the iceberg as nanoplastics, which are thousands of times smaller than microplastics, and likely more numerous than microplastics were not measured. The migration of microplastics into the olfactory bulb is just one possible route. Animal models show some microplastics can access the brain through blood circulation by sneaking through the protective blood brain barrier.

What microplastics are made of

Environmental scientists have been documenting the accumulation of far-reaching plastics and microplastics in every corner of the globe for decades. Microplastics are the broken-down by-products of larger plastics manufactured for consumer goods. Scientists seem most concerned with the ubiquitous nature of single use, disposable plastics like the ones used in food packaging and water bottles. It so happens that these are the microplastics the Brazilian researchers encountered most often. They also found plastics used in adhesives, medical devices, textiles, and kitchen utensils. The majority of microplastics were polypropylene. Other commonly encountered microplastics were polyamide, nylon, and polyethylene vinyl acetate found in packaging, clothes and home goods. The identification of these plastics along with the fact that microplastics have been found in nasal passages suggests indoor air is the most likely source of exposure.

Neurotoxicity of microplastics

While the pathway whereby microplastics reach the brain remains unproven, their presence in the brain is established. Researchers will continue to explore the toxic effects of microplastics on brain tissue and function. A few possible effects are likely. Endocrine effects are foremost amongst plastics. Plastics are made of a variety of endocrine disrupting compounds which are shown to contribute to thyroid effects, insulin resistance, diabetes and fat storage. Endocrine disruptors are believed to contribute to female reproductive cancers as well. Neurotoxic effects can be anticipated by the physical presence of microplastics in brain tissue where they act as a foreign body, inciting oxidative stress and an inflammatory response in the brain. Previous animal models have shown neuroinflammation and neurotransmitter imbalance. Another concern is the mechanical effect of microplastics simply pressing against and if large enough, displacing healthy brain tissue.

Microplastics in general have been linked to a variety of health impacts including decreased male fertility, antibiotic resistance, food allergies, preterm births and placental inflammation, and more rapid spreading of cancer cells in the gut.

Lowering indoor air levels of microplastics

The presence of microplastics in brain tissue is significant but equally noteworthy is the fact that breathing contaminated air is the proposed source. The lead author of the study said, “breathing within indoor environments could be a major source of plastic pollution in the brain.” Environmental scientists have long found that a home typically harbors higher concentrations of air pollutants than the outdoors. Reflecting on the endless supply of plastics and their ubiquitous nature in our environment, we may be interested in minimizing our exposure to microplastic contaminated air.

With indoor exposure representing our greatest source of air pollution and microplastic exposure, and with the average American spending nearly 19 hours a day in their home, the quality and purity indoor air is vital. The good news is that we have much more control over the quality of the air in our home than outside our home. There are several measures that can lower the level of indoor pollution and microplastics.

• Use of natural materials for clothing, upholstery, furniture, carpet and rugs such as wool, wood, cotton or leather for example.
• Minimize the use of canned foods.
• Frequent mopping and frequent vacuuming with HEPA-filter vacuum.
• Avoid body products made with plastic beads.
• Minimizing the use of single use plastics such as food storage bags, plastic tea bags, utensils and water bottles.
• The use of stainless steel or bamboo cooking utensils and wooden cutting boards.
• Use of MERV 8 rating air filter or better, and replacing no less than every 3 months
• Use of air purifiers with HEPA or MERV filtration.

Conclusion

Microplastics and the chemicals they are made of have been linked to endocrine disrupting effects such as certain cancers and decreased fertility rates. Microplastics have recently been found in brain tissue where they likely contribute to negative endocrine effects and neurotoxicity in part, from inflammation, oxidative stress and by negatively impacting neurotransmitter balance. Microplastic contaminated indoor air is likely our greatest source of exposure. Since we can influence the quality of air in our homes, those concerned about the neurotoxic effects of microplastics can improve air purity by implementing the measures listed above. Doing so can minimize exposure to indoor air pollutants and along with decreasing the risk of environmental related illnesses.

References:

Microplastics Have Been Found in the Human Brain. Now What? — Medscape — November 27, 2024

Amato-Lourenço, LF, Dantas KC, Ribeiro, G. et. Al. Microplastics in the Olfactory Bulb of the Human Brain. JAMA Netw Open. 2024;7(9):e2440018. September 16, 2024

Marine Microplastics Linked to Neurologic Dysfunction — Medscape — March 07, 2025