What Are Microplastics? Fragments Found in Human Lungs, Blood for First Time

Concern about microplastics has risen to new heights in recent weeks after researchers confirmed they had been detected in human blood and lungs for the first time.

The full health implications of microplastics in humans remain unknown. But we know that they are in our blood, they are in our lungs, they have even been found in the placentas of unborn children—and they are made to last.

Microplastics are tiny particles of plastic released into the environment as a result of human plastic waste. These particles can vary widely in size and shape, but generally they are considered to be microplastics if they are less than five millimeters in length, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).

Microplastics can come from larger bits of plastic debris that degrade into smaller pieces. They can also be released into the environment in the form of microbeads—pieces of plastic deliberately designed to be tiny that are often used as exfoliants in health and beauty products.

A stock photo shows plastic particles seen on a human fingertip. Microplastics have been found in human blood and lungs and their health implications are still unknown. pcess609/Getty

The study of microplastics is relatively new, with scientists developing standardized field methods for studying them. But already, we know that they have been found basically everywhere on Earth, from the summit of Mount Everest to the bottom of the ocean.

This may only be the tip of the iceberg. Human plastic pollution continues to be a huge problem after a plastic production spree over the past several decades.

In the early 2000s, the amount of plastic waste generated rose more in a single decade than it had in the previous 40 years. In all that time, most of the waste has gone to landfill, become part of uncontrolled waste streams, or simply been dumped into the environment and at sea. Today, humans still produce 300 million tons of plastic waste every single year, according to the United Nations Environment Programme.

In a study released on March 24 this year in the journal Environment International, scientists reported that they had found multiple types of plastic in blood samples supplied by 17 out of 22 anonymous healthy adult donors for the first time.

Alice Horton, anthropogenic contaminants scientist at the National Oceanography Centre in the U.K. who was not involved in the study, told the Science Media Centre: "Despite the low sample numbers and low concentrations detected, the analytical methods used are very robust and these data therefore unequivocally evidence the presence of microplastics and/or nanoplastics in blood samples.

"This is a concerning finding given that particles of this size have been demonstrated in the lab to cause inflammation and cell damage under experimental conditions."

Professor Dick Vethaak, an ecotoxicologist at Vrije Universiteit Amsterdam in the Netherlands who was involved in the study, told The Guardian newspaper he was particularly concerned about how plastic particles could affect babies and young children.

"We also know in general that babies and young children are more vulnerable to chemical and particle exposure," he said. "That worries me a lot."

In another study published on March 29 in the journal Science of the Total Environment, scientists also announced detection of microplastics in human lung tissue, with 39 microplastics identified in 11 of the 13 lung samples studied.

The question now is what this means for our health. Vethaak told The Guardian that we "urgently" need to find out, adding: "Are the particles retained in the body? Are they transported to certain organs, such as getting past the blood-brain barrier?"

We know a little bit already. At least one study has suggested microplastics can latch on to human blood cells and possibly alter their ability to transport oxygen. More disturbing implications may be revealed with time.

The U.N. aims to put together a legally binding agreement to be signed by countries by the end of 2024 that it hopes will address the full life cycle of plastic and reduce plastic pollution, including microplastics.