Making fluoride drugs can also be done without Pfas, show UvA chemists
There are still very few good alternatives to Pfas, the unbreakable chemicals that accumulate in the environment and pose a threat to public health. However, UvA chemists did manage to produce fluorine-containing drugs and pesticides without using the “eternal chemicals”.
“Pfas are perhaps one of the biggest environmental problems of our time,” says Jelena Stanić, PhD student in Timothy Noël’s Flow Chemistry research group (HIMS) at the UvA. In recent months, they worked on a way to produce drugs and pesticides without using Pfas. At the end of August, the researchers published the results in the journal Science.
Accumulation
Regarding the global Pfas problem, this is a small step. After all, Pfas are everywhere: it is in the air, in rivers, in soil and also in our food and drinking water.
More than its toxicity – in high concentrations, some types of Pfas are known to cause cancer or changes in liver function – the fact that Pfas do not break down is the biggest threat. Stanić: “Now the concentrations we ingest are still low, but they will continue to accumulate - in nature and in the human body - eventually making it an ever bigger problem.”
Irreplaceable
For this reason, the Netherlands, together with Germany, Denmark, Sweden and Norway, advocated a total PFAS ban in the EU last year. That soon proved to have some snags: the now thousands of different Pfas are present everywhere in industry, from medicines to coolants. An independent commission is currently investigating the social and economic impact of all these chemicals and the EU vote on the issue has been postponed to 2025.
For some applications of Pfas, alternatives can be used, but for some medicines it remains difficult for the time being, Stanić explains. “Because Pfas drugs contain fluorine (see box.), they are broken down by the human body at much lower rates than other pharmaceuticals. That is way they are much more effective, and you can also use a lower dose of them. It is very unlikely that Pfas in medicines are going to be banned anytime soon.”
Pfas, short for poly- and perfluoroalkyl substances is an umbrella term for already more than five thousand types of chemicals that do not degrade in nature.
The substances were discovered in the 1950s when chemists experimented with fluorine. Fluorine is an element in chemistry that we know from toothpaste, for example. It is an element whose atoms we use in many more products, for example medicines or pesticides. When fluorine occurs in a particular way (namely a carbon atom with two or more fluorine atoms), it is known as Pfas. Pfas has grease- and water-repellent properties and is therefore also used in non-stick coatings of pans.
The downside came to light only later. Because of these strong properties, Pfas molecules are not degradable and accumulate in nature. Hence the nickname: forever chemicals.
What will most likely be banned, however, are most of the reaction substances and intermediates needed to make Pfas products. Indeed, many of these products end up straight into nature because manufacturers still discharge them into rivers with wastewater.
Mount
And that is exactly where UvA chemists have come up with something. How can you still produce products containing Pfas, such as fluorinated medicines, without releasing Pfas? The UvA chemist used a starting material without fluorine, which is passed through a bed of fluoride salt in a closed system. Because the fluorine remains in the closed system, no Pfas is released into nature in the process.
The product that comes out of the closed system is not yet the final drug. It is, as it were, an “mount” with fluorine atoms that can be attached by a chemical reaction to another molecule. But agrochemicals such as pesticides can also be made with the mount.
Moreover, the molecules created with the UvA mount are safer than most Pfas-compounds. According to the official EU definition, it is a Pfas, but they can still decompose in nature. This is because the attachment is not as strongly bound to the rest of the molecule as it is for most Pfas. Although the chemist got positive feedback from companies in industry, it is too early to move the method to a larger scale. First, the researchers want to further investigate the method and make it safer in the lab.
