Microplastic exposure linked to changes in behavior and brain alteration

Microplastics, tiny particles of plastic less than 5mm in size, have become a ubiquitous environmental pollutant, infiltrating air, water, and food chains globally. While the pervasive nature of microplastics and their detrimental effects on marine organisms are well-documented, there has been limited research on the health impacts of microplastic exposure in mammals. 

A team of experts led by Professor Jaime Ross at the University of Rhode Island set out to investigate the potential health consequences of microplastic exposure on mammals. 

Focus of the study

The study specifically focused on neurobehavioral effects, inflammatory responses, and tissue accumulation. 

The results suggest that microplastic exposure in mammals, including humans, is a serious health concern. Among other complications, the researchers found a potential link to Alzheimer’s disease.

Ross and her research team exposed both young and old mice to varying levels of microplastics in their drinking water over a three-week period. 

What the researchers discovered 

The experts found that exposure to microplastics led to both behavioral changes and alterations in immune markers in the liver and brain tissues of the test subjects. Strikingly, the study mice began to exhibit behaviors akin to dementia in humans, with the effects being more profound in older animals.

“Current research suggests that these microplastics are transported throughout the environment and can accumulate in human tissues; however, research on the health effects of microplastics, especially in mammals, is still very limited,” said Professor Ross. 

“This has led our group to explore the biological and cognitive consequences of exposure to microplastics.”

Behavioral changes 

The study showed that the infiltration of microplastics was as widespread in the body as it is in the environment. Surprisingly, this linked directly to behavioral changes, particularly in older test subjects.

“To us, this was striking. These were not high doses of microplastics, but in only a short period of time, we saw these changes,” said Ross. 

“Nobody really understands the life cycle of these microplastics in the body, so part of what we want to address is the question of what happens as you get older. Are you more susceptible to systemic inflammation from these microplastics as you age? Can your body get rid of them as easily? Do your cells respond differently to these toxins?”

Microplastics found in every organ

To answer these questions and understand the physiological systems contributed to the observed behavioral changes, the researchers dissected several major tissues. They included the brain, liver, kidney, gastrointestinal tract, heart, spleen, and lungs. 

Alarmingly, the team found that the microplastic particles had begun to bioaccumulate in every organ, as well as in bodily waste.

Study implications 

The implications of this study are significant, as they suggest that microplastic exposure may induce behavioral changes and immune system alterations. These changes possibly contribute to the development of conditions like Alzheimer’s disease. 

Researchers need to conduct more research to fully understand the long-term effects of microplastic exposure and their lifecycle within the body. This study highlights the urgent need for further investigation into the potential health impacts of microplastics on humans and other mammals.

Crossing the blood brain barrier 

“Given that in this study the microplastics were delivered orally via drinking water, detection in tissues such as the gastrointestinal tract, which is a major part of the digestive system, or in the liver and kidneys was always probable,” said Ross. 

“The detection of microplastics in tissues such as the heart and lungs, however, suggests that the microplastics are going beyond the digestive system and likely undergoing systemic circulation.”

“The brain blood barrier is supposed to be very difficult to permeate. It is a protective mechanism against viruses and bacteria, yet these particles were able to get in there. It was actually deep in the brain tissue.”

Future research 

Brain infiltration also may cause a decrease in glial fibrillary acidic protein (called “GFAP”), a protein that supports many cell processes in the brain, results have shown. 

“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,” Ross said. “We were very surprised to see that the microplastics could induce altered GFAP signaling.”

Ross said that in future research, her team wants to understand how plastics may change the ability for the brain to maintain its homeostasis or how exposure may lead to neurological disorders and diseases, such as Alzheimer’s disease.

The study is published in the International Journal of Molecular Science. 

More about microplastic exposure

Microplastics, tiny plastic particles less than 5 millimeters in size, have become a growing concern due to their widespread presence in the environment and potential health impacts on humans and animals. They can originate from various sources. These include the breakdown of larger plastic items, microbeads in personal care products, and synthetic fibers shed from clothing during washing.

Researchers are still actively studying the health impact of microplastic exposure, and they have yet to make definitive conclusions. However, we outline some potential health impacts and areas of concern below.

Physical impact

Once ingested, microplastics can accumulate and possibly lead to physical harm. For example, in marine organisms, there is evidence that microplastics can block digestive tracts or alter feeding behavior by creating a false sense of fullness.

Chemical impact

Microplastics can absorb and carry organic pollutants like polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). If ingested by humans or animals, there’s a potential for these toxic chemicals to be released and cause harm.

Biochemical impact

Some studies suggest that microplastics can cause inflammation, stress, and alter physiological processes in marine animals. The degree to which this translates to human health is still under investigation.

Endocrine disruption

Plastics often contain additives like phthalates and bisphenol A (BPA). When ingested, these can act as endocrine disruptors. These are chemicals that interfere with the body’s endocrine system and produce adverse developmental, reproductive, neurological, and immune effects.

Vector for pathogens

Microplastics can serve as vectors for pathogenic bacteria. While the significance of this in terms of human health impact is not yet clear, there’s a potential concern about the spread of harmful bacteria in environments where microplastics are prevalent.

Impact on food chain

A wide range of marine life, from small zooplankton to larger fish, ingests microplastics. Humans consume these organisms directly or indirectly. This leads to a potential for bioaccumulation of microplastics and associated pollutants in the food chain.

Uncertain long-term effects

The long-term effects of chronic exposure to microplastics, especially at low levels, are still unknown. Research on this topic is ongoing.

It’s important to note that we find microplastics almost everywhere, including in the air we breathe, the water we drink, and the food we eat. However, the actual concentration and exposure levels vary. Additionally, the human body might excrete many of the microplastics ingested. However, the efficiency and implications of this process are still under study.

Given the potential risks, many countries have taken steps to reduce microplastic pollution, such as banning microbeads in personal care products. Nonetheless, given the ubiquity of plastic in modern life, microplastic pollution is a complex issue that requires multidimensional solutions.

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