What is microplastic?
The difference between macro- and microplastic is set to be 5 millimetres. Everything below 5 millimetres can be categorised as microplastic.
Microplastic can come from 2 different sources. Broken plastic products are a considerable factor, but also wear of products releases a lot of microplastic. An example of a larger product that turns into microplastic over time could be a plastic bag that is degraded to smaller and smaller pieces in the course of months or years. If it is on the surface of the sea and thus exposed to UV light from the sun, this process is much faster. If the bag sinks to the bottom of the ocean where the water is dark and stagnant, the degradation process stops and the bag can be there for hundreds of years.(*)
Wear of products such as textile and tires are also examples of microplastic sources. Every time we wash our clothes in the washing machine, millions of fibres are worn of and end up in the sea environment. This kind of microplastic from broken plastic products and wear is called secondary microplastic. Wastewater treatment plants cannot keep back those little particles, and if they are retained in the sludge they end up in the fields(*). More than 50% of the danish wastewatersludge is brought out to fields as a fertilizer supplement and in this way plastic ends up in our environment.
Today we don’t know how much plastic pollution the individual sources each add to the environment, making it difficult to find solutions.
Microplastic in lotions, toothpaste and paint
Microplastic can also be directly produced. A good example is microplastic that is blended into toothpaste, scrub lotions and paint. Microscopic beads of microplastic is blended into these products to have a scrubbing and grinding effect, most often polyethylen (PE) or polypropylen (PP). There can be up to 350.000 pieces in one single lotion. This form of microplastic is called primary microplastic.
The app 'Beat The Microbead'
Plastic Change works to completely phase out primary microplastic that is blended into cosmetics and other care products. Read more about how to scan your way around products with added microplastic using the app: 'Beat The Microbead'.
In January 2018 a report was released (Danish only), made by COWI for The Danish Environmental Protection Agency (EPA), about the lack of knowledge on microplastic - both nationally and internationally.
This report was the runner-up to a previous report released in 2015 about the sources and amounts of microplastic in Denmark which collected worldwide research on microplastics in wastewater. The report (2015) was the first suggestion of an overview of microplastic sources in Denmark. Many assumptions underlie the conclusions of the report, among other things the fact that the sources of microplastic come from tires especially. Based on theoretical calculations the report concluded that car tires is by far the largest source of microplastic discharge by approx. 60%. However, this is yet not measured and is still only in theory, which the newest report from 2018 also confirms - we still don't know the amount of microplastic in nature, where it comes from, or even how to properly measure it. The report from 2015 was therefore a first important study, however a desk job, and the report from 2018 urges that we still remain to find out whether those numbers in the reports can be confirmed in nature. Are tires and road stripes, textile laundry and more the number one causes?
This is something we continue to learn a lot more about in the Plastic Change project: Plastic free Roskilde Fjord (briefly described here). With the project in Roskilde fjord, we get completely new knowledge about the extent of microplastic in beach sand, the column of water, lugworms and clams, and we research in absorption and transportation in the food chain as well as analyse all sources. By analyzing the content of microplastic locally in wastewater treatment plans in Roskilde fjord, before and after purification, we get important knowledge about whether the wastewater treatment plants retain the microplastic that can be found in beauty products and laundry. International studies show that wastewater treatment plants only partly retain the microplastic, but we still need to understand where it ends up. That is why we also analyse the sludge from the wastewater treatment plants. At least 50% of the wastewater sludge in Denmark is dispersed as fertilizer in Danish fields. In this way, microplastic potentially ends up in the fields and can be washed out to lakes, streams and thus the ocean.