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Size doesn’t matter – not even for chemicals

Chemical Pollution

Size doesn’t matter – not even for chemicals

Published on 26 Sep 2019

The EU Commission has started to investigate if polymers should be registered under the EU chemicals legislation REACH, which means that information on their hazards for human health and the environment needs to be provided.

This has turned out to be something of a hot potato since opinions on the matter differ. Some say yes, some say no – others ask how and to what extent.

In this drama, there are two main characters – monomers and polymers. Monomers are the building blocks of polymers, and polymers are the main ingredient of a wide range of materials – most notably plastics.

Monomers are registered under REACH – unlike polymers – due to the fact that these molecules are both small and extremely reactive.

In the human body, for example, these molecules are so eager to interact with their environment that they many times attack the tissue, causing permanent damage to our DNA and increasing the risk of cancer.

“Bigger molecules may be toxicologically relevant”

Even though polymers are made up of monomers, they have long been considered to be too big to have a harmful effect on the human body. It has been said that all molecules with a molecular weight above 1000 Da are risk-free as they are too big to be bio-available.

However, there is no real scientific basis for this assumption, bigger molecules may be toxicologically relevant. Fluoropolymers are, for example, known to be bio-available well above sizes of 1000 Da.

Regardless of the polymer’s size, the material for which they are mainly used is causing huge problems. The rampant consumption of plastics in the world today means that the material piles up in enormous amounts in our ecosystems. It has, for example, been suggested that there will be more plastics than fish in the ocean by 2050.

What happens when polymers eventually degrade in the environment?

“Polymers can break down into microplastics and release harmful substances”

Polymers are extremely persistent. If you bury a plastic bag in the ground and dig it up 50 years later, it will probably look the same as before (although much dirtier). But certain factors can speed up the degradation process substantially. The use of solvents is one such factor, another one is sunlight.

Under these conditions polymers can, on the one hand, break down into microplastics – which have been recognised as major pollutants in the environment – and on the other hand, release harmful substances that were previously part of the polymer.

In 2007 when REACH was adopted, polymers were considered to be less hazardous than monomers and too complicated to register due to the high number of possible polymer chains.

Instead of solving the problem, it was postponed and polymers were exempted from registration.

That means that today, we lack a lot of vital information about them. A REACH registration will lead to increased knowledge about how polymers are used, the toxic properties of them, how persistent they are and what happens when they break down. It would give us a much better understanding of the plastics that are being used in the EU today.

I think few would argue that this isn’t kind of important stuff to know in this age of plastic bonanza.

A registration of polymers also means that the legislative treatment of them would be in line with all other chemicals, something that is way overdue in my opinion.

Jerker Ligthart
Senior Chemicals Advisor at ChemSec