No sustainability debate without chemicals

Clara Löw (Oeko-Institut), Source: Oeko-Institut

I am typing typical uses of persistent organic pollutants (POPs) into an Excel table and asking myself how I can spot a pattern there. My task is to analyse usage patterns, but as yet I have no idea how to come at that. I notice how the table constricts my thoughts and start writing words on a blank sheet of paper: pesticides, flame retardants, plasticisers, textiles and motor oils – and many more. I don’t know which term it was – or it may have been the combination – that suddenly reminded me of a chart from the literature that I referred to in my Master’s thesis a year and a half ago. It showed annual emissions from various products listed according to groups of organic chemicals – ethers, aromatic compounds, cyclic non-aromatic compounds and so on.

“A little bit of chemistry”

At my home computer I use the file containing the literature references from my Master’s thesis to raise my screen – it was the thickest one in my bookshelf. What a coincidence. I find the paper! And at that point the file provides a sudden burst of motivation: Because an entirely overlooked aspect of sustainability debates is the issue of chemicals in products and everyday materials and their release during manufacture and use, during transport, in the waste phase and during combustion. What with organic vegetable growing, calls for less plastic and more action on climate change, how are we to find room for “a little bit of chemistry”? I can contribute something to that right here, with my task of analysing usage patterns. Significantly reducing the release of chemicals into air, water and soil in order to minimise their adverse impacts on human health and the environment is one of the targets of the United Nations’ sustainability agenda (SDG 12.4). This is especially important for those chemicals that have particularly worrying properties.

Flame retardants in the atmosphere

The organic flame retardants present in many everyday products (including sofas, mattresses and electronic goods) have various worrying properties. Most of these chemicals are volatile, which means that they diffuse into the atmosphere. This release of a specific substance into the surrounding air is termed its volatility – that is, its ability to evaporate. Some volatile organic compounds (VOCs) occur naturally; an example is the substance given off by conifers which results in the smell of pine. There are also many human-made (anthropogenic) airborne pollutants that become part of the air. VOCs play a part in a number of processes in the atmosphere:

1. For example, they can form “secondary particulate matter” as a result of oxidation processes in the air.
2. When bound to the surface of other fine particles, they can travel vast distances in the air – including as far as the Arctic.

Via these behaviour patterns, organic airborne pollutants affect …

• …climate change processes, because secondary aerosol particles can form clouds.
• …the ozone layer through the formation of reactive oxygen species.
• …urban air quality – with adverse impacts on human health. Airborne pollutants increase the aerosol content of the atmosphere.

They are thus involved in processes that contribute to three of the nine “planetary boundaries” defined by Steffen et al. (2015). Furthermore, when deposited on the surface of fine particles, organic chemicals that are harmful to health can be inhaled, with direct consequences for the people affected. Anthropogenic (semi-)volatile organic substances are particularly worrying when they are halogenated – that is, when they contain fluorine, chlorine or bromine. These are abbreviated as X-(S)VOC. Such substances are very likely to meet all the criteria for a persistent organic pollutant (POP): they are probably persistent, bioaccumulative and toxic and can spread a long way in the environment without degrading. What other things policy-makers could do Existing strategies in the chemicals regulations include:

• Reducing chlorofluorinated compounds – notably via the Kyoto Protocol – to protect stratospheric ozone.
• Replacing organic solvents with water-based systems to reduce tropospheric ozone.
• Phasing out the use of toxic substances.

More recent findings indicate that the following points also need to be addressed:

• Volatile chemical products (from indoor sources) make a significant contribution to the formation of secondary particulate matter.
• Alongside the focus on ozone and toxic substances, greater attention also needs to be paid to PM2.5. PM2.5 refers to fine airborne particles with a diameter of less than 2.5 micrometres. One micrometre is a thousandth of a millimetre. These particles advance particularly far into the lungs. To address this problem, all the relevant precursor substances and classes should be identified and regulated.

Flame retardants are underrated airborne pollutants In the public arena, little thought is usually given to chemicals as an aspect of sustainability. Substances such as flame retardants stand for the large group of anthropogenic atmospheric pollutants. McDonald et al. (2018), among others, have established that substances in this group contribute more to organic atmospheric pollution than was supposed: many products that we use every day incorporate chemicals to provide particular product characteristics, such as fire resistance. McDonald et al. call these additives “volatile chemical products”. My task of analysing the ways in which POPs are used helps raise awareness of these compounds and the environmental impacts described above. The patterns thus identified can draw attention to organic airborne pollutants and their typical applications as anthropogenic chemicals. And suddenly I have an idea for how I can look for a pattern among the chemical structures, the life cycle phases with emissions risk, the function of the substances and the typical materials in which they are used. But I will still end up with a big Excel table.

Clara Löw is an expert in pollutant assessment and substance evaluation, the circular economy and plastics. She works in the Sustainable Products & Material Flows Division in Freiburg. In 2020 Clara Löw was awarded Frankfurt University’s sustainability prize for degree theses for her Master’s thesis on “Organic flame retardants in the ambient air of Frankfurt am Main” and her account of the importance of anthropogenic chemicals in environmental issues.