Wetenschap - 21 mei 2015

Tracking down nanoplastic pollution

Rob Ramaker

In the next few years, environmental scientist Bart Koelmans will be studying Dutch rivers, streams and lakes to see whether they are polluted with miniscule plastic particles. In laboratory tests these ‘nanoplastics’ appeared to have a much more negative impact on organisms than larger fragments of plastic.

However, there are as yet no methods of demonstrating the presence of this form of pollution in water. Koelmans’ project recently received a grant of 650,000 euros from science-funding organization STW, topped up with 220,000 euros from other organizations.

Our oceans are polluted with a ‘plastic soup’. This phenomenon was brought to our attention by photos of dead birds whose stomachs were full of plastic. In practice, however, plastic waste breaks down fast, often into micro-particles of less than 5 millimetres across. Experts suspect that that there are even smaller particles of plastic floating around in our environment. Miniscule fragments less than 100 nanometres in diameter, one thousand times smaller than a hair. These kinds of nanoplastics are created, for example, at the sprayer head of 3D printers in operation. ‘But they have never been proven present in fresh water,’ says Koelmans, personal professor at the Aquatic Ecology and Water Quality Management chair group.

Koelmans wants to develop measuring instruments which can demonstrate the presence of nanoplastics and monitor them. Microscopes and the naked eye are of no use for this purpose. Specialized instruments are needed, which can unmask nanoplastics using material properties such as speed of movement in a flowing liquid. It remains a challenging project, says Koelmans. If only because there is all sorts of other waste such as iron particles and traces of paint floating in water.

The environmentalist wants to study the impact of this plastic pollution too. The first experiments - with nanoplastics made in the laboratory – are alarming. ‘Larger plastic particles go in one end and come out the other. At worst, smaller animals get constipated,’ says Koelmans. But nanoplastics are so small that other rules apply. They can enter the body through the intestinal wall, for instance. What is more, they bind many more harmful substances. Some fragmented knowledge about this had been gathered in the laboratory. Ultimately Koelmans wants to be able to make a systematic and realistic estimate of the risks.