Beware of perfluorinated compounds (PFAS)
No other class of substances is as toxic, stable and at the same time used so frequently in everyday products as perfluorinated compounds (PFAS). It is urgent time for action, says Prof. Martin Scheringer of ETH Zurich.
One group of chemical compounds keeps popping up in news stories about contaminated clothing and food packaging, as well as groundwater contamination: the perfluorinated compounds - or by full name: the poly- and perfluorinated alkyl substances (PFAS). They improve the spreading and flow properties of liquids and are highly water- and grease-repellent. As a result, they are used in many different consumer products and industrial applications1. They are very widespread in impregnating agents, for example for fitted carpets, outdoor clothing and food packaging, but also in personal care products such as skin creams. As a result, we frequently come into contact with these substances in everyday life and also absorb them into our bodies. Industrially, they are used, for example, as process chemicals in the manufacture of Teflon, and they are also used in fire-fighting foams in airports, which has led to significant groundwater and drinking water pollution in many countries.
PFASs have a toxic effect on the liver and kidney, among other things.
The problem: PFAS have a toxic effect on the liver and kidney, can impair the development of embryos and inhibit the body's immune responses, and some are also known to promote the development of tumors. In addition, the compounds are so chemically stable that they do not degrade significantly in the environment over periods of decades to centuries. There is no other group of substances of practical importance that has such a high chemical stability as PFAS and at the same time occurs in such large quantities in everyday products and is released into the environment after use. As a result of the continued use of PFASs, environmental pollution is steadily increasing. A second major problem with PFAS is the large number of these substances and the lack of knowledge about many of them. 4000 different PFASs are known; my ETH colleague Zhanyun Wang recently compiled a list of PFASs for the OECD.2. However, environmental chemistry and toxicology research over the past 25 years has focused on only a small group of about 25 PFASs. The best known of these are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). These substances have now been extensively studied, and their environmental behavior and toxicity are well known.
As a result, although these PFASs, which have been identified as problematic, have now been regulated worldwide and are gradually being replaced, in the vast majority of cases they are being replaced by other PFASs whose toxicity has been little studied. However, their persistence in the environment is known to be as great as that of the well-studied PFAS. There is therefore a danger that the problem of the extremely long-lived environmental pollution caused by PFASs will not be solved now, with the switch to fluorinated alternative substances, but on the contrary will be exacerbated.
Zurich Declaration
In November 2017, a group of more than 30 scientists and government officials from 14 countries met in Zurich for a workshop brought together by Zhanyun Wang and Justin Boucher and Martin Scheringer. The goal of the workshop was to develop a strategy for dealing with PFAS. The discussions at that time resulted in the "Zurich Declaration", which was recently published in the journal Environmental Health Perspectives.3. In it, the researchers emphasize that the regulation of extremely persistent substances must be fundamentally reconsidered. The Zurich Declaration is open for signature by further persons4.
Currently, the regulation of chemicals is usually based on the detection of undesirable effects on human health and the environment. However, this approach is not practical for extremely persistent substances. If the multitude of PFASs on the market are used until their adverse effects are documented in detail, significant amounts of these substances will enter the environment. The substances are then irrecoverable and will circulate in the environment for decades or even centuries, contaminating human food and drinking water.
Only for essential applications
Due to increasing concentrations in the environment, toxic effects inevitably occur sooner or later - this can be stated beyond doubt, even without knowing the toxic effects in detail. This is a very central point that suggests the regulation of chemicals on the basis of extreme persistence alone. This would be a major step forward in environmental policy.
The applications of the numerous PFASs are so diverse (and they are also subject to quite different legal regulations) that there is no simple and direct solution to the problem. One possibility, however, is to distinguish in a systematic way between essential and non-essential applications of PFAS. In particular, certain industrial applications under extreme conditions could be classified as essential for the time being. Examples include the use of PFASs in hydraulic fluids, insulating and sealing materials in aerospace, and hard chrome plating, where PFASs are used, among other things, to suppress spray mists that contain chromium and are thus very toxic. In many consumer products, however, PFASs are not essential, and applications in consumer products contribute heavily to human and environmental exposure. Such applications should therefore be discouraged with high priority.
References
1 OECD: Portal 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: Zurich Statement on Future Actions on Poly- and Perfluoroalkyl Substances (PFASs). Environmental Health Perspectives, August 31, 2018, doi: 10.1289/EHP4158
4 Zurich Declaration/IPCP: Publication of the 'Zurich Statement on Future Actions on Per- and Polyfluoroalkyl Substances (PFASs)
More links:
German Federal Environmental Agency: Per- and polyfluorinated chemicals (PFCs)
Allergy, environment and health: Perfluorinated compounds
German Federal Institute for Risk Assessment (BfR): Materials and links on perfluorinated compounds
German Federal Institute for Risk Assessment (BfR): Perfluorinated surfactants: a problem in food and feed?
