They are called PFAS, perfluoroalkyl substances and they are chemical compounds widely used in a large number of products and materials for their resistance and fire-retardant properties, i.e. for their ability to make products such as technical clothing waterproof and to fats. But they have also been under investigation for some time due to the negative effects that their persistence in the environment has on the health of animals and people. A comparative transcriptional analysis – published in Toxics magazine and carried out by scholars from the University of Bologna and the University of Padua – has now confirmed that the effects of exposure to PFAS are conserved at the molecular level both in different tissues and in different species, and produces consequences both in humans and in other animal species.
Why you should only buy PFAS Free clothing
“From our analysis we have identified and reported several genes that show a coherent and evolutionarily conserved transcriptional response to PFAS,” says Federico Manuel Giorgi, professor at the Department of Pharmacy and Biotechnology of the University of Bologna, who coordinated the study. “These results show for the first time that different PFAS molecules influence hormonal pathways and metabolic pathways, for example by increasing the accumulation mechanisms of fatty acids and weakening the immune system”.
PFAS, highly resistant chemical compounds, fireproof and water repellent, have been used for over 60 years in non-stick coatings, fire-fighting foams, waterproof fabrics, pesticides, building materials and cleaning and personal hygiene products. The Organization for Economic Cooperation and Development (OECD) includes 4,730 different molecules in this category, making this group the largest family of emerging pollutants.
The spread of PFAS in the environment
In fact, due to their high molecular stability, these materials end up spreading widely in the environment, where they can remain for years. In particular, PFAS enter water bodies in large quantities, from where they can travel great distances, entering aquatic ecosystems and moving up the food chain to humans. Traces of these substances have been identified in breast milk, placenta, serum, seminal fluid and hair.
Despite this evidence and the negative consequences of PFAS for human health brought to light by various studies, an overall analysis of all the data collected on the topic had not been carried out to date. The researchers then collected 2,144 samples from seven different animal species to examine responses at the molecular level of PFAS exposure.
“Our goal – explains Giorgi – was to highlight the molecular effects induced by PFAS not only at the level of single genes, but also on various molecular pathways and cell types. Our research thus offers a complete view of the molecular mechanisms underlying the toxicity of PFAS, in order to offer solid data on which to base the choices necessary to safeguard public health and the environment”.
The negative effects on health
The results obtained in fact confirm a series of negative effects on health produced by exposure to PFAS. For example, a strong regression of lipid metabolism and transport and other processes related to ovarian development, estrogen production, ovulation and physiological functioning of the female reproductive system. All elements that can explain the harmful effects of PFAS on fertility and fetal development.
The collected data also show that exposure to PFAS produces an upregulation of the ID1 gene, involved in the development of various types of cancer, including leukemia, breast and pancreatic cancer. Epidemiological data also suggest that high exposure to these materials can significantly increase the mortality of individuals affected by malignant neoplasms of lymphatic and hematopoietic tissues, such as spleen, liver and bone marrow.
The study also appears to confirm the toxic effect of PFAS on the immune system. The researchers have in fact highlighted the mechanism that could explain the weakening of immune reactions, antibody production and responses to vaccinations, observed in particular in children exposed to PFAS during the prenatal and postnatal period. Exposure to PFAS also increases the serum concentration of inflammatory and oxidative stress markers and thus promotes the development of systemic diseases, such as liver damage and cardiovascular disease, including atherosclerosis and thromboembolic events.
Through bioinformatic data analysis and thanks to recent developments in gene expression data mining, scholars were also able to further analyze the possible consequences of PFAS exposure by predicting their effects on the metabolome (the set of all the small molecules present in a cell involved in the processes of the organism). In particular, it emerged that PFAS molecules are linked to an increase in the levels of various types of lipids: evidence which confirms that exposure to these substances increases the concentration of triglycerides and cholesterol in the blood.
The most comprehensive analysis of transcriptional response to PFAS ever
“This study is the largest analysis of the transcriptional response to PFASs ever performed, with significant implications for understanding the impact of PFAS exposure on living organisms and the environment,” concludes Giorgi. “We believe that the obtained results can offer a new perspective on the molecular responses to PFAS exposure and we hope that they can provide the basis for the development of strategies to mitigate the harmful effects of these substances”.
The study was published in Toxics magazine with the title “Cross-Species Transcriptomics Analysis Highlights Conserved Molecular Responses to Per- and Polyfluoroalkyl Substances”. Livia Beccacece, Filippo Costa and Federico Manuel Giorgi from the University of Bologna (Department of Pharmacy and Biotechnology) participated, together with Jennifer Paola Pascali from the University of Padua.
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Photo by Steve Gale / Claudia Black / Greg Rosenke
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