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The exposure also caused changes to proteins in liver and brain tissues that determine an individual’s immune function, the researchers from the University of Rhode Island, US, further found after exposing young and old mice to microplastics in drinking water over a period of three weeks.
Plastics, including microplastics, are among the most pervasive pollutants on the planet, easily making their way into the air, water systems and food chains around the world.
Studying microplastic accumulation in tissues, including the brain, the research team found that the infiltration of microplastics was as widespread within the body as it was in the external environment, leading to behavioural changes, especially in the older test subjects.
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”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 Jaime Ross, corresponding author on the study.
”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?” said Ross.
Investigating the extent of microplastic percolation within the body through dissection, Ross’s team found that plastic particles had begun to accumulate in the tissues of every organ, including the brain, liver, kidney, gastrointestinal tract, heart, spleen and lungs, as well as in bodily waste.
”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,” said Ross.
Microplastic infiltration in the brain could also lower levels of a protein that supports many brain cell processes, the glial fibrillary acidic protein, or the GFAP, the study showed.
”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,” said Ross. ”We were very surprised to see that the microplastics could induce altered GFAP signalling.” Through future research, Ross intends to understand how plastic exposure in brain could lead to neurological disorders and diseases, such as Alzheimer’s disease.