We hear a lot about microplastics – those tiny pieces of plastic that have become so ubiquitous in our water, air and soil that they can now be found in human blood. These tiny pieces of plastic are a product of degraded waste, as plastic does not break down biodegradablely like other materials. Plastics make up much of our packaging, toys, cars, toiletries and building materials; the list goes on and on.
What’s more, plastic is made up of numerous toxins and chemicals that, when broken down, seep into every aspect of our lives. But how do they actually get into our body?
Microplastics found in human blood
In a new study published in the journal Science of the Whole Environmentresearchers are investigating how microplastics enter our blood at the molecular level. For this study, the scientists focused on polystyrene plastics, which are most commonly used in food packaging, and nanotubes, which are used in sporting goods, coatings and electronics.
They found that microplastics likely enter the human body through diet and inhalation before being ingested by macrophages, white blood cells that surround and kill foreign materials as part of your body’s immune response. A receptor found in macrophages known as TIM4 binds to microplastics in an attempt to break them down.
Microplastic effects on humans
According to the author of the study Masafumi Nakayamaprofessor at Ritsumeikan University in Honshu, Japan, by understanding the process of macrophages, researchers can better understand how they impact on health in the body.
When TIM4 receptors are damaged while trying to bind to microplastics, for example, the immune response causes inflammation in the body. But if the receptor remains intact when it binds to and ingests the microplastic, then no inflammation occurs. Whether the receptor is damaged or not depends on the type, size and shape of the microplastic. For this study, the researchers compared carbon nanotubes with polystyrene.
“This is the reason why carbon nanotubes cause inflammation in the body, and polystyrene usually doesn’t,” says Nakayama.
This is the first time we have looked at this process at the molecular level. But we already know that nanoplastics may be able to penetrate cell membranes in the gut and make their way to other organs, says Michael Kleinmanprofessor of environmental toxicology at the University of California, Irvine, who was not involved in the study.
“They can also deposit on sensitive lung tissues and cause irritation and inflammation,” he says.
Is microplastic harmful?
Once microplastics and their smaller cousins, nanoplastics, break down in the environment, they are difficult to remove from water and air because they are so small. And there’s still a lot we don’t know about how harmful these pollutants can be. But it probably has an impact.
“There is evidence from animal and cell culture studies that NP (nanoplastic) exposure is pro-inflammatory and can induce oxidative stress,” says Kleinman. “When occurring in humans, these changes may be associated with lung and heart disease, but definitive human studies are currently lacking.”
Kleinman claims that BPA (Bisphenol A), phthalates and heavy metals that break down in plastics are known to be toxic to humans. Plastics that contain leached toxic components like BPA are probably worse for us, but they are far from the only problem.
“The physical presence of nanoplastics in biological tissues can be irritating enough to cause local inflammation in the lungs and intestinal lining,” says Kleinman.
We are only just beginning to understand the scope of the problem, as research into how microplastics affect human health is still in its infancy.
How to reduce microplastics
Kleinman says we still don’t know enough about how many nanoplastics are prevalent in our environment and how much accumulates in our bodies. And if they are already broken down in the air, water and soil, avoiding them becomes almost impossible.
While in your own life you can reduce your exposure to plastic by buying products and foods that are not packaged in plastic, choosing glass containers over plastic, carrying your own bags, avoiding plastic water bottles, etc., it’s hard to understand our full exposure. Because after all, microplastics are a societal and global problem that cannot be solved simply at home.
Read more: Americans are the number one contributor of plastic waste