The participants of the Bonus Summer School (BSS) of the PFAStwin project had the unique opportunity to learn more about PFAS from the scientist who first discovered the presence of PFAS in the environment, and recognised the danger of their ubiquitous pollution. In the first lecture, Prof. Giesy pointed out some unusual properties of PFAS that distinguish them from all other chemical substances. They are often amphiphilic, which means that they repel both oils and water. PFAS have a low vapour pressure, but unlike pollutants such as organochlorine chemicals or PCBs, they are very soluble in water.
Due to the unique properties of PFAS, it was not possible to adopt findings from already well-studied groups of pollutants. The lack of methods or standards to identify these substances in the environment posed a serious scientific challenge. Prof Giesy and his group wrestled with a number of important questions related to PFAS: How widespread are they in the environment? Are they locally, regionally or globally distributed? What are the sources of PFAS? Are they bioaccumulated and/or biomagnified? What are the mechanisms of accumulation? Are there particularly exposed species? Do concentrations decrease with distance? To what extent should we be concerned about atmospheric transport? In September 2001, the results of the global survey were published in ES&T, and this publication is currently cited more than 1,400 times!
In the lecture "PFAS Analysis", Prof Giesy explained why PFAS are incredibly difficult to quantify. The concentrations in the environment are extremely low, while PFAS contamination is not only present in laboratory equipment, but also in the instruments themselves (e.g. many parts are made of Teflon). To make matters worse, some researchers were unlucky when analysing PFOS, as it turned out that a human bile acid has the same retention time, parent ion and transition ion, the most abundant product. Prof Giesy explained how this problem can be easily solved, but also emphasised how difficult the analysis of PFAS can often be.
The next lecture was dedicated to the astonishing progress made in the field of environmental forensics. From the perspective of a scientist who did biodiversity monitoring decades ago, the possibilities of DNA metabarcoding must seem almost like magic. Instead of laboriously searching for specimens of invasive or endangered species, we can detect them simply by analysing the DNA present in water samples. It is even possible to estimate the size of their population.
The last lecture was dedicated to the harmful effects of PFAS, and it was as exciting as a thriller, full of twists and turns. An interesting example is PFOA, which is not carcinogenic but looks so similar to cholesterol that it becomes embedded in cell membranes. This process disrupts the ability of cells to communicate properly and fight neighbouring cancer cells. PFAS can also be very insidious: they bind to proteins in our bodies, and take a very long time to be excreted. For many PFAS, the half-life in the human body is longer than four years.
Prof Giesy shared many interesting experiences and valuable knowledge related to PFAS. At the end of his lectures at the BSS, we discovered something even more praiseworthy about him: he is a great role model for young scientists who are at the beginning of their careers.
Whenever he spoke about his discoveries, he praised the invaluable contributions of his team members. He made another grand gesture: at the beginning of the second day of the BSS, he presented gifts to each member of the organising team, saying: “You should always honour the people who do the work.” Despite all his achievements, he gave the impression of an incredibly humble and friendly person, who was willing to answer any question and always encouraged participants to share their ideas and guesses.
The Bonus Summer School was a great opportunity for participants to learn about interesting and relevant topics from lecturers gathered all around the world, from Canada to Japan. In addition to knowledge, the lecturers shared valuable experiences, which inspired numerous questions from the audience.
