What are microplastics? The term microplastics is used for small plastic particles of different origin, size and chemical composition. The size specifications for microplastics are not uniformly defined in the literature and usually vary between 0.001 mm and less than 5 mm.

This small particles come from different sources and microplastics can be classified either as primary or as secondary microplastics. As an example plastic pellets which are manufactured industrially are a kind of primary microplastics. Secondary microplastics are caused by chemical and physical aging or decomposition processes, for example from plastic bags or plastic bottles.

To get a deeper introduction about microplastics, please read our ePaper and learn more about the main sources and how they affect the world oceans.

An introduction to microplastics

What are microplastics at all and how do they affect us and our environment? Read our ePaper and learn more about primary and secondary microplastics.

Primary and secondary microplastics

Definition of the term microplastics

Microplastics’ is a term commonly used to describe very small pieces of plastic debris in the environment resulting from the disposal and breakdown of products and waste materials. They are not a specific kind of plastic but rather any type of plastic fragment less than a size of 5mm.

They are defined by EFSA (European Food Safety Authority) and ECHA (European Chemicals Agency) as follows:

  • EFSA: Heterogeneous mixture of differently shaped (plastic) materials referred to as fragments, fibers, spheroids, granules, pellets, flakes or beads in the range of 0.1 μm – 5 mm (05/2016)
    Nanoplastics from approximately 1 to 100 nm (0.001 – 0.1 μm)
  • ECHA: ‘microplastic’ means a material consisting of solid polymer-containing particles, to which additives or other substances may have been added, and where ≥ 1% w/w of particles have (i) all dimensions 1nm ≤ x ≤ 5mm, or (ii), for fibres, a length of 3nm ≤ x ≤ 15mm and length to diameter ratio of >3. Polymers that occur in nature that have not been chemically modified (other than by hydrolysis) are excluded, as are polymers that are (bio)degradable (08/2019)

Microplastics are divided into the classifications primary and secondary microplastics.

Primary microplastics classification

They are manufactured industrially in form of plastic-based granules or pellets (PE, PP, PET, PS, PVC, PA etc.). Primary microplastics can be subclassified into type A and type B.

Primary microplastics type A

They are manufactured intentionally as microplastics:


Primary microplastics type B

Type B microplastics can result from the usage of larger macroplastic products:


Secondary microplastics classification

They are microscopic plastic fragments derived from the breakdown of larger plastic debris through chemical and physical aging, decay processes, photodegradation and other weathering processes. The sources of secondary microplastics are for example:


Worldwide distribution of microplastics


The impact on marine environment

There is a staggering amount of microplastics in our worlds ocean and meanwhile microplastics can be found even in the deep sea. It’s a steady debate how much tons of microplastic is distributed, a 2015 study estimated that there was between 93 and 236 thousand metric tons of microplastics in the worlds ocean.

Due to new studies, microplastics can have a physical impact on organisms. Lugworms which are an important source of food for other animals eat less and their energy levels suffer if they reside in microplastic contamined ocean sediments. Furthermore, microplastics can be found in fish stomaches and this is only one step away from the human food chain.

Global releases of primary microplastics to the world oceans


The impact on human health

Microplastics might have an impact on human health but still a lot of research is needed, especially in regard of the degradation of microplastics and potential formation of nanoplastics in the human gastrointestinal (GI) tract.

An overview has been reported by EFSA in their statement about the presence of micro- and nanoplastics in food (see corresponding link on the main page):

  • The digestive tract of marine organisms contains the largest quantities of microplastics
  • Microplastics have the potential to be transferred between different trophic levels
  • Only limited data are available on the occurrence of microplastics in foods. Available data are from fish, bivalves, crustaceans, honey, beer and salt
  • There is a lack of information on the fate and behavior of micro- and nanoplastics in the GI tract. The available data on toxicokinetics only include absorption and distribution, whereas no information is available on metabolism and excretion
  • Only microplastics smaller than 150 μm may translocate across the gut epithelium causing systemic exposure. The absorption of these microplastics is expected to be limited (<= 0.3%)
  • Only the smallest fraction (size < 1.5 μm) may penetrate deeply into organs
  • It is unknown, whether ingested microplastics can be degraded to nanoplastics in the GI tract
  • Some engineered nanomaterials have shown toxic effects, however, toxicity data for nanoplastics are essentially lacking for human risk assessment

Do Siegwerk inks contain microplastics?

Only very few raw materials used by the printing ink industry fall under the definition of microplastics. The vast majority of those are waxes, which are necessary additives for the improvement of the rub- and scratch resistance.

You may also read the statement of the European Printing Ink Association (EuPIA) about Microplastics in printing inks and printed products (see Useful Links No 9).