Rain is more than just a weather event. It has long been considered a symptom of the climate crisis, for example, because it is increasingly absent for too long or, conversely, pelts the earth in huge quantities. And it holds even more bad news, because all kinds of pollutants rain down from the sky with the water. One substance class in particular is causing increasing concern, the so-called perfluorinated and polyfluorinated alkyl substances, in short: PFAS. The fluorochemicals are precipitating all over the world, even in the Tibetan Highlands or in Antarctica – and in amounts well above some health guidelines, as recently in a recent study was to read.
Video call to co-author Martin Scheringer from the Swiss Federal Institute of Technology (ETH) Zurich. The chemist – black pullover, friendly smile – has been researching substances on which practically everything rolls off for 15 years. Among other things, PFAS can be found in coated frying pans, in sandwich paper, weather jackets, waterproofing sprays, in chain grease, carpets and fire-extinguishing foam. They are also common tools in technical production processes, for example in the semiconductor industry.
“The fatal thing about the substances is that they are so stable,” says Scheringer. Neither microbes nor sunlight can crack the molecules in which fluorine and carbon atoms are chemically linked extremely tightly. PFAS that get into the environment from products, factory chimneys and sewage remain there for at least decades. They accumulate in soil, water, groundwater and are distributed all over the planet, including through rain.
The health guideline values have continued to fall in many countries
For their study, Scheringer and scientists from Stockholm University focused primarily on four particularly well-studied PFAS representatives, including the acids PFOA (perfluorooctanoic acid) and PFOS (perfluorooctanesulfonic acid), which are now banned for most applications in many countries. How much of it is in the rainwater did not surprise the chemist. “The pollutant concentrations were known. We just compiled them from studies that had already been published,” he says.
But the health guideline values for these substances have been lowered in many countries over the past ten years, for drinking water, for bodies of water and for the soil. “Often thousands of times, and for the last time in June by the US Environmental Protection Agency. So much so that the actual concentrations in the environment are now in the range of these values or just above.” The strictest guideline values for a liter of drinking or sea water today are in the range of billionths to millionths of a milligram.
Several potentially harmful substances are already in every human being
Although PFAS are not acutely toxic, it is known that some members of this group of substances can weaken the immune system of children, disrupt lipid metabolism, impair fertility and reduce the birth weight of newborns. Liver and kidney damage as well as testicular cancer are also attributed to PFAS representatives such as PFOA and PFOS. “With these substances, we found in Germany that we really do find them in every person, regardless of particularly polluted, regional conditions,” says Marike Kolossa from the Federal Environment Agency.
In a monitoring session, her team found, among other things, high levels of exposure to the fluorochemical PFOA in the blood of children and adolescents. So high that in every fifth test subject, “according to the current state of knowledge, it is no longer possible to rule out damage to health with sufficient certainty,” says the toxicologist. “And with the chemical PFOS, we found that the exposure level was exceeded in two to three percent of the blood samples, where we definitely expect health effects.” The current report on Europe-wide human biomonitoring “HBM4EU” is transnational to similar results.
This is not only bad for people who actually get sick, but also costs a lot of money. In 2019, the Nordic Council, an association of primarily Scandinavian countries, the health-related consequential costs of environmental pollution with PFAS in the European Economic Area to 52 to 84 billion euros per year.
The problem cannot be solved purely technologically
A team from New York University recently came up with similar figures for the USA, with costs between five and a half and more than 60 billion euros for therapies, medication and absences from work. With a share of 17 percent, the adiposity-promoting effect of PFAS has a particularly strong impact, as at the end of July in the journal Exposure and Health was to read. “A lot of people don’t realize that it’s not just about cancers in people in a few hotspots, but about many different possible health effects that can potentially affect almost everyone,” says Linda Kahn, co-author of the study. In order to avoid even more costs, alternatives for the substances must urgently be found and, wherever possible, drinking water treated and soil remediated. “Doing nothing will be even more expensive,” emphasizes the scientist.
However, the problem cannot be solved purely technologically. A research team from the USA recently reported in the specialist journal Science of successful laboratory attempts to break down certain PFAS into harmless parts using a common chemical solvent at moderate temperatures. So far, temperatures of around 1000 degrees Celsius have been necessary, the authors write. In the future, the method could help to break down pollutants in landfills or factories, for example. “But when it comes to the problem that the entire environment is contaminated, they unfortunately don’t help one bit. You can’t do everything wrong for decades and then hope for a miracle solution,” says Scheringer.
The European Union is discussing phasing out the entire group of substances
Meanwhile, the amounts of PFAS in the environment continue to rise, although emissions of the substances PFOS or PFOA, which are banned almost everywhere, are falling. “At least in China, a lot of PFOA is still being produced. In addition, there are large contamination areas from which the substances are distributed around the world. So there’s still more to come,” says the researcher. In addition, many manufacturers have switched to other members of the PFAS group of substances that have not previously been regulated, but are not necessarily less harmful. The group includes thousands of different fluorochemicals.
In order to get the situation under control, a proposal is currently being discussed in EU bodies to withdraw the entire group of substances from circulation. Dispensable applications should be deleted first, while essential ones should initially continue to be allowed. “Blood tubes, for example: PFAS help to make the surfaces so smooth that the blood cannot clump in them. This is definitely an essential application. But mass-produced products such as ski wax, pan coatings or food paper can be solved differently. And you have to solve that differently,” emphasizes Scheringer.
Industry associations are opposed to such plans and warn of the loss of innovative strength and jobs. PFAS should continue to be assessed individually for possible harmful effects, for example the Federation of German Industries (BDI) demands in a position paper. “With thousands of substances, however, that would take centuries,” complains Scheringer. And pending a potential ban, the fluorochemicals continue to flow into the environment with no possibility of retrieval.