Microplastic is a collective term for particles of different plastic materials that are smaller than 5 mm. It is produced by abrasion and decomposition processes of plastic, but is also added to personal care and cleaning products. Microplastics are now everywhere and enter the environment and, of course, the water cycle in a variety of ways. According to a 2019 study by WWF, we ingest about 5 grams of microplastic per week – the weight of a credit card. Because microplastics are everywhere, it is impossible not to ingest microplastics. We inhale the majority. We also ingest the small plastic particles through our food and drinking water.

Researchers have now detected microplastics in water all over the world: in lakes, rivers, oceans, in bottled water as well as in tap water. A large-scale study by the NGO “Orb Media” in cooperation with the University of Minnesota in the USA on microplastics in tap water samples from all over the world already showed in 2017 that more than 80 percent of the water samples analysed at that time contained microplastics, also in the German samples – even in very small quantities. Since about one third of drinking water in Germany is obtained from surface water (1.7 billion cubic metres), it is not surprising that drinking water can also contain microplastics. Incidentally, the proportion was higher in bottled water (plastic and glass), which is probably related to the packaging and the closure.

Is microplastic in drinking water harmful to health?

According to the WHO, microplastics – as things stand at present – are not harmful to health. However, this is difficult to believe. There are still far too few studies on the topic of microplastics in drinking water and their effects.

Experts assume that particles larger than 150 micrometres are excreted by the body. But whether this also applies to much smaller microplastic particles has not yet been sufficiently researched. It is also unclear what health consequences accumulations of microplastics have in the body. The WHO study sees three sources of danger for humans from microplastics in water:

– First, the plastic particles themselves, when they accumulate in the body and are ingested by the body through adsorption.
– Secondly, the chemical substances (e.g. additives such as BPA) that are released by the particles to the body or that they absorb
– The biofilms that settle on the particles and on which toxins can accumulate.

The ingestion of microplastics into the human body can occur through the absorption of smaller particles via the intestines. Microplastics have already been detected in human blood and the lungs of patients. So far, research does not know an exact answer to the question of the exact effects of microplastics on the human organism. However, the findings so far from the field of marine and environmental research are dramatic. Fish and other sea dwellers absorb microplastics both through food and through filtration of the sea water. They are damaged or at least weakened by the plastic and the substances that adhere to it. In addition to physiological disorders, the consequences include increased tumour formation and a significantly higher mortality rate among marine animals.

In 2021, scientists at the University of Marburg used experiments on cell cultures and mice to investigate how microplastics affect immune cells and blood vessels. The research results have shown that microplastics can cause inflammatory reactions in tissue. The results of the study also suggest that microplastics may also be a risk factor for cardiovascular disease.

Even though there is still no conclusive scientific evidence on the exact effects of microplastics on human health, people do not want to have such foreign substances in their own bodies. Therefore, microplastics should generally be included as a risk factor in the assessment of water quality.

At least with drinking water, a corresponding drinking water filter from Seccua helps to reliably remove microplastics. Its ultrafiltration membrane has such small pores that microplastic particles down to a defined size of 1 µm (micrometre) are reliably removed.