The European Union has pledged to ban them by 2030, but they are still found in many everyday objects: non-stick pans, food packaging, disposable dishes, laptop cases, fabrics treated against stains or water. humidity, cosmetics or even under our skis. Unknown to the general public, perfluoroalkyl or polyfluoroalkyl compounds – the “PFAS” – represent a threat to the environment as well as to our health. Director of the American Institute of Environmental Health Sciences until 2019, Linda Birnbaum has made this one of her main concerns. Author of more than 600 peer-reviewed journalistic studies, this renowned scientist says that while she was still in office, the Trump administration prohibited her from saying that certain chemicals in this family could “cause” cancer. Today her word is freed, and she no longer refrains from alerting on this question – and on many others still. Interview.
L’Express: You have just received the Ramazzini Institute Prize, awarded each year to a scientist for his contribution to public health. On this occasion, you said that PFAS were more problematic than dioxin. For what reasons ?
Linda Birnbaum : Dioxins have never been intentionally produced. These contaminants appear during certain production processes. Manufacturers were not happy to have to change the way they work to avoid or clean up this unintentional pollution. But in a way, it was easier than trying to eliminate PFAS, because these chemicals are very useful: at least 200 categories of use have been identified. I certainly have some on my waterproof boots, for example, or on my cell phone. Moreover, they are very numerous. There are only 29 molecules in the family of chlorinated dioxins. If we add the brominated dioxins, we arrive at a hundred, maybe 200 but not much more. For PFAS, we know that 600 of them are produced in the USA, but in reality there are thousands. In 2017, the OECD counted 4,700, and since then, new ones appear almost every day: the latest estimates count at least 9,000! Some are intentionally synthesized, others are co-products that appear during their manufacture. Most importantly, they make billions of dollars for their manufacturers, while no one has ever made a dime with dioxins.
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But are PFAS as toxic as dioxins?
Let’s say that dioxins have never been produced in very large quantities. Exposure limits are much stricter for dioxins than for PFAS, around 1000 times lower. The big difference is that PFAS are everywhere. They contaminate all living organisms, animals and even plants. We are all exposed to it, and we are all imbued with it, at much higher levels than by dioxins. Moreover, dioxins activate only one cellular receptor, while PFAS activate many. It is therefore much more difficult to understand by which mechanisms they act. But their health effects are increasingly well documented. They appear multiple, and very similar to those of dioxins. PFAS cause cancer, disrupt our hormonal and immune systems, they can lead to autoimmune diseases, kidney or even liver damage … PFAS could also help increase cholesterol levels, obesity or even risk of preeclampsia in pregnant women.
How do we get infected?
Much emphasis has been placed on ingestion, through water and food. But in reality, we contaminate ourselves in any way we can. Dusts that contain PFAS end up on our hands and end up being ingested or inhaled. There may also be a passage through the skin.
“Manufacturers like 3M or Dupont had information on the toxicity of these molecules for many years”
If PFAS are everywhere, how can we demonstrate their harmful effects on health?
We have laboratory studies in animal models and in cell models, with human cells, and we also have epidemiological studies. Of course, we cannot determine an individual risk, in particular because of the very great variability in the human species: what we are looking for are population trends.
There are also data related to the exposure of employees in factories that manufacture or use these products. Manufacturers like 3M or Dupont had information on the toxicity of these molecules for many years, but had not made it public. They were only recently discovered.
Certain PFASs, in particular PFOA and PFOS, have however already been banned. Isn’t that enough to protect us?
The levels of impregnation of the population with these two molecules decreased considerably from the mid-2000s. But recent data show that this decline has stopped. It probably comes from amounts in the environment which somehow re-contaminate us. It is not for nothing that these products are called “forever chemicals”, eternal chemicals. They cannot be destroyed, the fluorine carbon bond which characterizes them is the strongest in all organic chemistry, we hardly know anything that can break it.
PFOA and PFOS have been replaced by others, believed to be less toxic. Wrongly. For example, there is GenX, which has been the subject of studies by teams of toxicologists: it seems to have the same effects as previous generation PFAS … But the worst is that we have not even a precise idea of what the population is really exposed to: when we study the presence of PFAS in the environment or in the blood, we discover some that we do not even know!
Are you pleading for a total shutdown of PFAS production?
Personally, I think we should largely limit their use. In some cases, they can be difficult to replace. An article released in 2019 classified their uses into three categories. Category one, those that are unnecessary. Category two, those which are useful but which may have a less toxic alternative. Category three, those which are really essential. Some 90% fell into category one or two. In other words: we can do without most of them. Do we really need these products to make our skis glide better, for example?
How to regulate such numerous compounds?
This is currently the subject of many discussions, at least in the United States. I plead for them to be regulated as a single class, with the same regulation applying to all of these molecules. So far, the US Environmental Agency has proposed to group them into 24 subclasses, but I do not find this solution satisfactory, as some products do not fall within the defined categories. The industry, for its part, applauded with both hands. In this case, you can be sure that there is a wolf. The industry explains that some of these compounds are less toxic than others, but this is very relative. Especially since the exposures are continuous, and we do not know the consequences of being exposed to several hundred of these products at the same time.
“China continues to produce molecules banned everywhere else”
What about the regulation of PFAS in Europe?
Europe is much more advanced than the United States. The European Commission has already said that it wants to treat them all as one class, and in the medium term reduce their production and their uses in consumer products to a strict minimum. It’s already better than in the United States. But on the other hand, we must not forget that we do not know anything about African or Latin American countries. And that China continues to produce some of the molecules that have been banned elsewhere in the world. We even have no idea of the global production of PFAS, even though they are very mobile molecules.
Isn’t it already too late, when these products are persistent?
This is an interesting question for research. Even incineration has difficulty destroying perfluorinated compounds. But perhaps we could imagine stopping production altogether, and reusing the molecules present in the objects we throw away, and in the environment, much like we try to do for rare metals.
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What do you personally use for cooking?
In stores you often see “PFOA-free” casseroles. This is a clue that they probably contain other PFAS. In the United States, however, we have two organizations, “The environmental working group” and the “Green science policy institute” which recommend consumer goods without PFAS. I looked at what they recommended, and bought a non-stick pan or two. But basically, do we really need it? We might as well cook with our traditional pans and a little bit of fat, and that would be fine too!
