Highly toxic, extremely persistent and widely used
No other class of substances is as stable and as frequently used in everyday products as fluorosurfactants. It's high time for action, says Martin Scheringer.
A group of chemical compounds frequently cited in the news about contaminated clothing and food packaging and groundwater pollution is the fluorosurfactants – or, to give them their full name, poly- and perfluoroalkyl substances (PFASs). They improve the spreadability and flow properties of liquids and are highly water and oil repellent; they are therefore used in many different consumer products and industrial applications1.
PFASs are very common in impregnating agents, such as for fitted carpets, outdoor clothing and food packaging, but also present in personal care products such as skin creams. This means we frequently come into contact with them in everyday life and absorb them into our bodies. These substances are also applied industrially, for example as process chemicals in the production of Teflon, and are used in fire-fighting foams at airports – which has led to considerable groundwater and drinking water pollution in many countries.
The main problem is that PFASs are toxic to the liver and kidneys, they can interfere with embryonic development, inhibit the body's immune responses, and in some cases promote the development of tumours. What’s more, these compounds are chemically so stable that they don’t break down significantly in the environment over decades and even centuries. No other group of substances of practical importance is as chemically stable as PFASs, while at the same time present in such large quantities in everyday products and released into the environment after use. Due to the continuous use of PFASs, environmental pollution is steadily increasing.
A second serious problem is the large number of PFASs and the lack of knowledge about many of them. 4,000 different PFASs are known; my ETH Zurich colleague Zhanyun Wang recently compiled a list of these for the OECD2. Yet over the past 25 years, environmental chemical and toxicological research has concentrated on only a small group of about 25 PFASs, the best known being perfluorooctanoic acid (PFOA) and perfluorooctane sulphonic acid (PFOS). These substances have now been extensively studied and their environmental behaviour and toxicity acknowledged.
Having been identified as harmful, these particular PFASs have now been regulated worldwide and are gradually being replaced. However, in the majority of cases they are replaced by other PFASs whose toxicity has so far not been investigated extensively – although they are known to persist in the environment to the same extent as the well-documented PFASs. So there’s a real danger that switching to alternative fluorinated substances will not solve the problem of the extremely persistent environmental impact of PFASs, but instead aggravate it.
Zurich Statement
Last November, a group of over 30 scientists and government officials from 14 countries met in Zurich for a workshop that I led together with Zhanyun Wang and Justin Boucher. The aim was to develop a strategy for dealing with PFASs, and from those discussions emerged the Zurich Statement, which we recently published in the journal Environmental Health Perspectives3. Here we emphasise that the regulation of extremely persistent substances must be radically reconsidered. The Zurich Statement is open for signature by other parties4.
"One possibility is to distinguish systematically between essential and non-essential applications of PFASs."Martin Scheringer
At present, the regulation of chemicals is generally based on the detection of any adverse effect on human health and the environment. It’s an approach that’s not appropriate for extremely persistent substances. For if the many PFASs on the market continue to be used until their adverse effects have been documented in detail, considerable quantities of these substances will end up in our environment. They’ll then be irretrievable and will circulate in the environment for decades or even centuries, contaminating human food and drinking water.
For essential applications only
The increasing concentrations in the environment will inevitably lead to toxic effects sooner or later – of this there can be no doubt, even if we don’t yet know the details of those effects. That crucial aspect alone calls for the regulation of chemicals on the basis of their extreme persistence; this would be a major step forward in environmental policy.
The applications of the many PFASs are so diverse (and subject to such very different legal regulations) that there’s no simple, immediate solution to the problem. One possibility, however, is to distinguish systematically between essential and non-essential applications of PFASs. Certain industrial applications under extreme conditions could be considered essential for the time being, such as the use of PFASs in hydraulic fluids, insulating and sealing materials in the aerospace industry, and hard chrome plating, where it’s used to suppress chromium-containing, very toxic spray mists. In many consumer products, however, PFASs are not essential, but add considerably to the harmful impact on humans and the environment. High priority should therefore be given to eliminating such applications.
References
1 OECD: external pagePortal on Per and Poly Fluorinated Chemicals
2 OECD: The OECD releases a new list of PFASs
3 Ritscher A, Wang Z, Scheringer M, Boucher JM et al.: Zürich Statement on Future Actions on Poly- and Perfluoroalkyl Substances (PFASs). Environmental Health Perspectives, 31 August 2018, doi: external page10.1289/EHP4158