Microplastics may enter the brain through breathing – new research

Tiny plastic particles are everywhere: in the soil where our food is grown, the water we drink, and the air we breathe. They get there from the plastic we throw away and end up in landfills, rivers and oceans. There, plastic waste slowly breaks down, releasing tiny particles called microplastics and even smaller nanoplastics into the environment.

Microplastics are also increasingly being found throughout the human body. We don’t know how they got there, but there are three possible routes. We can ingest microplastics when we eat and drink, breathe them into our lungs, or absorb them through our skin. Recently, an alternative route has been proposed in which microplastics enter our noses and from there into our brains.

For a long time, the human brain was thought to exist independently of the rest of the body. A special layer of cells, the so-called blood-brain barrier, protects the brain from all kinds of pathogens and harmful substances. However, we now know that tiny plastic particles have been discovered in the human brain that can breach the blood-brain barrier.

New research suggests that the blood-brain barrier has at least one vulnerable point where microplastics can enter the brain. This potential entry point was proposed by researchers from the Free University of Berlin and the University of São Paulo. The nose has a special nerve called the olfactory nerve that detects smells.

The olfactory nerve runs from inside the nose through the skull directly to a part of the brain called the olfactory bulb. Researchers suggest that particles inhaled into the nose may somehow be transported along the olfactory nerve to the brain.

Researchers reached their conclusion by analyzing tissue samples from São Paulo residents who died and underwent routine autopsies by coroners. They removed the olfactory bulbs from these brains and analyzed them using various techniques.

Microplastics were present in the olfactory bulbs of eight of the 15 brains studied. However, there were only 16 microplastic particles among these eight samples. This is probably some consolation.

These 16 plastic particles included shards, spheres, and fibers and were made of polypropylene, nylon, and other plastics. Some of the fibers may come from clothing. This makes sense, since washing clothes made from synthetic fibers is a significant source of microplastics in the environment.

Some of the small plastic particles are missing

This new study is just one of many that have reported the presence of tiny plastic particles in the human body. Most of these studies concern microplastics, which are particles up to 5 millimeters in size. Few studies have investigated nanoplastics in the human body.

At less than a thousandth of a millimeter in size, nanoplastics are so small that they are difficult to detect without special equipment, which few scientists have access to.

Nanoplastics are important because, unlike microplastics, they are well-proven to be harmful to living cells. This is because nanoplastics are small enough to enter cells. Once invaded, it can kill cells.

Nanoplastics have been shown to kill cells in animal fetuses. This can lead to birth defects in animals when embryos are exposed to high doses of nanoparticles.

Fortunately, there is no evidence that birth defects in humans have increased significantly in recent years. Perhaps the placenta can prevent microplastics and nanoplastics from reaching the fetus.

We need to know more about the presence of microplastics, especially nanoplastics, in the human body. And you need to know how they get there in the first place.

This is what makes the new study in Berlin and São Paulo so interesting. This suggests a potential entry point from the nose to the brain. This leaves us with the question of what potential risks microplastics and nanoplastics pose to our health. The jury is out, and they’re probably feeling a little more nervous than before.

This article is republished from The Conversation under a Creative Commons license. Read the original article.