Microplastics: Distribution, sources, and state of research

Microplastics are ubiquitous. These tiny plastic particles have been detected in oceans, soil, the air, and even in the human body. But what exactly are microplastics? Where do they come from, and what does science say about what might happen to them?

What Are Microplastics?

Particles of plastic smaller than five millimeters are referred to as microplastics. According to the European Chemicals Agency (ECHA), they are synthetic polymers that are organic, insoluble in water, and mechanically degradable. Particles made of nanoplastic, which have a size of less than one micrometer (0,001 millimeters) and are thought to be particularly mobile in biological systems, are even smaller. There are two main categories of scientific discourse: Primary microplastics, which are intentionally manufactured in small sizes, for example for industrial applications or cosmetics.
Secondary microplastics, which result from the breakdown of larger plastic items – caused by abrasion, UV exposure, or mechanical stress.
European legislation also distinguishes between microplastic particles that have been “intentionally added” and those that have not been “intentionally released.”

Where Do Microplastics Originate?

Microplastics originate in a variety of ways and from a variety of sources. An analysis by the European Commission shows that the largest amounts of unintentionally released microplastics in the EU come from the following sectors (estimated maximum annual values):

Paints and coatings: approximately 863,000 tonnes per year; ship abrasion accounts for 25% of this. Tire wear: approx.

540,000 tonnes/year: 55% of which concerns cars
Plastic pellets: approx. 184,000 tonnes/year
Geotextiles and textiles: approximately 80,000 tons annually Additional contributions can come from packaging, especially when it ends up in the environment and gradually disintegrates. In such cases, secondary microplastics are formed, which can be significantly reduced through proper collection and recycling.

Microplastics in Drinking Water and Food Several studies have found microparticles in both food and drinking water – including fish, shellfish, salt, tap water, and bottled mineral water. Some studies have detected microplastics in both single-use and reusable PET bottles, as well as in glass bottles. Glass bottles had higher particle counts in some instances. The size of the particles and the kind of sample both have an impact on the number of particles. It is interesting to note that not all of the microparticles that have been detected are made of plastic. Only about 10% of the particles in some studies were actually identified as plastic. As a result, statements about the intake of microplastics through food remain uncertain.

What Does the Research Say About Its Applicability to Human Health?

The blood, lungs, placenta, and breast milk of various human beings have all been found to contain microplastic particles. At the moment, a lot of research is being done to see what kind of long-term effects this might have on health. Regarding intake levels, the often-cited claim that humans ingest a credit card’s worth of plastic (5g) every week has been disproved by recent studies. In point of fact, it only weighs 0.000004 g, and it would take approximately 20,000 years to accumulate the equivalent of a credit card. The results of animal studies cannot be directly applied to humans, but they have provided preliminary insights. As a result, statements regarding quantities or risks should be interpreted with care. The following information was once again published by the German Federal Institute for Risk Assessment in July 2025: “Based on current knowledge, there is no reliable toxicological evidence of health risks from the ingestion of microplastics via food.” This is a government agency that is scientifically independent and is in charge of assessing the health risks of substances. Additionally, the FDA (Food and Drug Administration) in the United States and the German Food Association emphasize that the most recent scientific findings indicate that there is no evidence that the presence of microplastics or nanoplastics in food poses a health threat. However, other types of dust, such as paper, aluminum, and wood dust, have already received negative toxicological assessments.

Research Status and Outlook

Scientific engagement with microplastics is still in its early stages. Internationally standardized definitions, measurement techniques, and risk assessments do not exist. Studies can be difficult to compare due to this lack of standardization, which sometimes results in contradictory conclusions. Yet fact-based debate and reliable data are crucial to developing sound long-term solutions.
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