Everything on Earth has fallen victim to plastic pollution, from our oceans to our food. Consequently, our bodies have accumulated unprecedented amounts of nanoplastic concentrations in organ tissues, including the critical cardiovascular, lung, and nervous systems. Today, scientists continue to uncover more distressing effects of microplastic exposure in the human body.
Increased accessibility and inexpensiveness of plastic products have made them a convenient resource for consumer goods and packaging. However, these temporary plastic products deteriorate into microscopic particles scattered throughout our environment. Studies confirm that microplastics have been found in the human body through daily consumption of fruits, vegetables, meats, and even water from plastic bottles. Despite knowledge of widespread plastic pollution, there remains a limited understanding of microplastics’ impact on human health.
A 2024 pre-print study examined microplastic contamination in the liver, kidneys, and frontal cortex of human autopsy samples from 2016 and 2024. Researchers concluded that every post-mortem organ was plastic-polluted, with the brain having the highest plastic concentration. The study revealed an average of 0.5% plastic by weight across 24 brain samples. Furthermore, it found that the microplastic concentration in brain samples from 2024 increased by 50% compared to the brain samples from 2016. This suggests that the presence of microplastics in the brain is growing at a rate mirroring the exponential increase of plastic pollution in the environment.
“The presence of microplastics in the brain is growing at a rate mirroring the exponential increase of plastic pollution in the environment.”
This statistic is shocking for neuroscientists and raises the question of how microplastics can easily travel against the highly protective blood-brain barrier. This barrier, a semipermeable membrane that protects the brain against viruses and foreign objects, could not guard against these microscopic particles. Researchers propose two explanations for this. The first is that plastics are lipophilic, meaning that microplastics easily embed within lipids. It makes sense, then, that the brain has the highest microplastic concentration because the brain has the second highest lipid concentration in the human body. Second, the brain receives a high proportion of blood flow, approximately 25-30% of all blood transported by the cardiovascular system. The transfer of lipophilic molecules across cellular membranes of the brain is directly linked to the cardiovascular system. These microplastics, combined with lipids in blood like cholesterol, can bypass the blood-brain barrier. Plastics also travel through fatty buildups in arteries, further allowing them to deposit in the brain at high rates.
These studies highlight the importance of researching the detrimental effects that microplastics may have on public health. Scientists postulate a correlational link between increased microplastic concentration and neurological disorders, including dementia. The same 2024 study included 12 post-mortem brains of people who died with dementia, finding 10 times more plastic by weight than healthy brain samples. While a larger sample size is required to better understand any links between microplastic concentration and health effects, the corroboration with other studies confirms that microplastics do selectively accumulate in the brain. Additionally, the researchers parallel the recent increasing microplastic concentration to two other variables: the exponentially rising plastic pollution in the environment; and the increasing global rates of Alzheimer’s disease and dementia.
A second study investigated mouse brains to simulate human brain activity and development. By exposing old and young mice to low doses of microplastics through water consumption, the Ross lab researchers discovered that these microplastics accumulated in every organ tissue, especially the brain. The model mice also exhibited symptoms that were similar to dementia in humans. The lab expected to see some inflammation in this experiment, but were surprised to see a significant decrease in glial fibrillary acidic protein (GFAP). This protein is critical in supporting cellular processes in the brain, but microplastics could alter the function of GFAP and its cellular signaling process. Its depletion is associated with early-stage neurodegenerative diseases including Alzheimer’s disease and depression.
Overusing plastic goods is more than an environmental catastrophe — it is a public health crisis. Given the potential role that microplastics play in neurological health, neuroscientists urgently seek to understand the impact of nanoplastics on cellular function and homeostasis. Additionally, today’s youth populations have been continually exposed to a concerning amount of plastic products in an increasingly dependent society. Recognizing that environmental microplastics can harm human health, it becomes important for public agencies to find ways to reduce plastic use.