by Marek Dosbaba, Product Marketing Manager for Earth and Materials Science, TESCAN
The health of our planet in regard to climate change, air pollution and waste management are of pressing concern today. In particular, people are now much more aware of the environmental impact of anthropogenic plastic waste due to the powerful visuals of vast rafts of plastic bottles, bags and other packaging out at sea, defacing our beautiful coastlines. More heart-wrenching are the images of wildlife that have perished as a result of man-made plastic pollution ingestion or entanglement. What is not so visible are the microplastic and nanoplastic waste materials that lurk in our waterways―and possibly our drinking water.
Micro and Nanoplastics
Figure 1: TESCAN scanning electron microscopy (SEM) image of examples of micro or nanoplastics in drinking water. Image courtesy of Martin Pivokonksy from the Institute of Hydrodynamics of the Czech Academy of Sciences.
In most cases, plastics are derived from non-renewable petrochemicals like crude oil, although some bioplastics have emerged recently synthesized from corn or starch converted to PLA (polylactic acid). They consist of long chained carbon molecules that can take hundreds of years to biodegrade. This is concerning, especially when so much plastic is employed for single-use applications like packaging.
Microplastics refer to plastic particles smaller than 5mm. Nanoplastics are particles of the same material in the sub 100 nm range (figure 1).
Microplastics can be classed as either primary or secondary. Primary microplastics are deliberately produced and may be used as feedstock pellets for a production process, e.g. injection molding, or used as-produced, e.g. in cosmetics or abrasives. Secondary microplastics are created as a result of the breakdown of larger plastic products by processes such as mechanical fragmentation, wear or erosion.
The fragmentation of plastics into micro and nanoplastics is exemplified in coastal regions where plastics are subjected to high amounts of UV radiation, in combination with physical abrasion from waves and sand.
Microplastics in Drinking Water
The effect of microplastics in drinking water has been identified as an issue by the World Health Organization. Researchers at the Institute of Hydrodynamics at the Czech Academy of Sciences took a closer look at this issue and published their findings from an investigation of Czech drinking water in the journal Science of the Total Environment.1
Figure 2: TESCAN SEM images of microplastics and details of differently shaped microparticles: fibers, spherical particles, fragments. Image courtesy of Martin Pivokonksy from the Institute of Hydrodynamics of the Czech Academy of Sciences.
Their study looked at water from three water treatment plants across the Czech Republic. They found microplastics present in all locations in both raw and treated water samples. They looked at samples down to 1 µm, which is smaller than any previous study conducted. In doing so, they found concentrations as high as 3,600 particles per liter in raw water and 630 particles per liter in treated water, with the majority (>70%) comprised of PET (polyethylene terephthalate), PP (polypropylene) and PE (polyethylene)―the most widely produced plastics worldwide. An additional 11 varieties of plastics were also identified (figure 2). The findings indicate that the water treatment plants were only 70-83% effective at removing microplastics.
Summary
The Institute of Hydrodynamics research has confirmed the presence of microplastics in raw and treated drinking water. This research is exceptional in that it evaluates the presence of microplastic particles not only in different water sources, but also in drinking water that has gone through the entire water treatment plant process. In addition, microplastics only 1 µm in size have been analyzed, which is unique compared to previous publications on this topic.
References
1. M. Pivokonsky, L. Cermakova, K. Novotna, P. Peer, T. Cajthaml, V. Janda, Occurrence of microplastics in raw and treated drinking water, Sci. Total Environ., 643 (2018), pp. 1644-1651, 10.1016/j.scitotenv.2018.08.102