Microplastics, tiny fragments of plastic less than 5 mm in size, have been detected in many ecosystems and organisms, raising concerns about their possible effects on human health. Thus, we will review the pathways by which microplastics can reach the central nervous system (CNS), the mechanisms that allow their transit through biological barriers such as the blood-brain barrier, and the potential neurotoxic effects.
For example, in a preliminary study, a series of human brain samples collected during an autopsy in early 2024 contained more tiny plastic fragments than samples collected eight years earlier.
The study’s lead author, Matthew CampenProfessor of Pharmaceutical Sciences at the University of New Mexico in Albuquerque, noted that “the concentrations we found in brain tissue of normal individuals, average age about 45 or 50, were 4,800 micrograms per gram,” or 0.5 percent by weight.
And it seems unclear whether in life these particles are fluid, moving in and out of the brain, or whether they accumulate in neurological tissues and promote disease.
For the study, researchers examined brain, kidney and liver tissue from 92 people who underwent forensic autopsies to verify cause of death in 2016 and 2024.
From our observations, we believe that the brain attracts smaller nanostructures, about 100 to 200 nanometers long, while some of the larger particles, one micrometer to five micrometers, go to the liver and kidneys,” Campen told CNN.
Increase in plastics
Over the past few decades, the production and use of plastics have increased exponentially, leading to increasing environmental pollution. Microplastics, which arise from the degradation of larger plastic products or are intentionally manufactured for use in consumer products, have been found in air, water, food and, alarmingly,, in biological tissues, including the brainThe presence of microplastics in the CNS raises concerns about their potential impact on neurological health and their possible relationship with neurodegenerative diseases.
Entry of microplastics into the body
Microplastics can enter the human body through a variety of pathways, including:
Ingestion: Microplastic contamination of food and drinking water is a major source of entry. Studies have found particles in a variety of food products, from seafood to salt and bottled water.
Inhalation: Airborne microplastics, particularly in urban and domestic environments, can be inhaled and deposited in the lungs, from where they could potentially migrate to other systems, including the circulatory system.
Skin absorption: Although less common, it has been postulated that microplastics in cosmetics and personal care products could penetrate the skin and enter the circulatory system.
Mechanisms of translocation across biological barriers
blood-brain barrier (BBB): The BBB is a selective structure that protects the CNS from potentially harmful substances. However, studies in animal models have shown that nanoparticles, and potentially microplastics, can cross this barrier. This could occur through mechanisms such as transcellular transport, immune cell-mediated translocation, or through disruption of BBB integrity by inflammatory processes.
Olfactory journey: Inhaled microplastics can directly access the brain through the olfactory mucosa and olfactory nerve, a pathway that provides direct access from the nasal cavity to the CNS.
Neurotoxic effects
Inflammation and oxidative stress: The presence of microplastics in the brain could trigger an inflammatory response, activating glial cells such as astrocytes and microglia. This inflammation could lead to an increase in the production of reactive oxygen species (ROS), causing oxidative damage to neurons and other CNS components.
Neurodegeneration: The accumulation of microplastics and the resulting inflammatory response could contribute to neurodegeneration, a process seen in diseases such as Alzheimer’s and Parkinson’s. Studies have suggested that Microplastics can affect synaptic function and neuronal signaling, promoting the loss of neurons and the degeneration of nerve connections.
Blood-brain barrier disruption: Chronic exposure to microplastics could compromise the integrity of the BBB, increasing its permeability and allowing other toxins or pathogens to enter the brain, amplifying neurotoxic effects.
Implications for public health
The presence of microplastics in the human brain and its potential negative effects on neurological health highlight the need for urgent measures to control and reduce exposure to these contaminants. This includes policies to reduce the use of plastics, improve waste management, and develop alternative materials that are less harmful to health and the environment. In addition, Further research is needed to fully understand the mechanisms of microplastic toxicity. and its relationship with neurodegenerative diseases.
Microplastics represent an emerging threat to human health and their potential impact on the central nervous system is of increasing concern. Evidence suggests that these contaminants can cross biological barriers and trigger neurotoxic effects.which could have serious consequences for public health. Concerted efforts are needed to mitigate microplastic pollution and protect the neurological health of current and future generations.
