Research: How do cells react to micro and nanoplastics?

Researchers from Germany have examined possible health effects of small plastic particles, answering questions about how microplastics could affect human tissue.

The smaller plastic particles are, the more easily they can be taken up by cells, according to the scientists from the German Federal Institute for Risk Assessment (BfR).

In addition, the shape, surface and chemical properties play an important tole in how the particles could affect humans.

Plastic particles enter the environment from weathering and decaying of polymer materials, car tyre and clothing abrasion and many other sources. As a result, various types of microplastic particles can be inhaled or ingested with drinks and food.

Current scientific evidence suggests microplastics are comparatively low risk to human health, because they are too big to be absorbed by human cells to any significant extent.

However, the situation is different with smaller particles, known as submicro- and nano-plastics.

These particles are between one nanometre (billionth of a metre, unit nm) and 1000 nanometres (equivalent to one micrometre) in size. It is not yet known for sure whether and to which quantities they can enter the human body.

‘With this study, we want to help to close the still rather large knowledge gaps in the topic of health effects of nanoplastics,’ says Dr. Holger Sieg, head of the research project. ‘However, these are laboratory experiments with cell cultures that cannot simply be transferred to humans.’

Holger Sieg and his team worked on submicrometre and nanoplastic particles and their effects on human small intestine and liver cells.

Because these particles are so small and difficult to study, it is not easy to gain reliable insights into their effects on human tissue. The BfR team used various microscopy and testing methods to do this.

The cells were exposed to various plastic types that are used in plastic tableware and cutlery or in food packaging.

The cells of the small intestine, as a natural barrier between the intestinal contents and the organism, proved to be rather resistant. Microplastics only “seeped” into the cell to a small extent.

The even smaller particles in the submicrometre range, on the other hand, could be measured in larger quantities in intestinal and liver cells. The particles either attached themselves directly to the cell membranes or were trapped in small bubbles of cell membrane, a process known as endocytosis.

It is not yet clear whether such artificial inclusions can disrupt the normal metabolism of the cell.

Plastic particles could also bind potentially harmful substances to themselves and introduce them into the cell as a “Trojan horse”.

Photo by Misael Moreno