Eternal chemicals. PFAS accumulate in our tissues. What impact do they have on health?

According to the latest analysis, which saw the light of day in the scientific journal “Environmental Health Perspectives”, exposure to a very long-term mixture of chemicals in the environment – specifically perfluoroalkyl and polyfluoroalkyl compounds – called PFAS for short – leads to changes in biological processes related to a wide range of diseases.

A team of researchers at the University of Southern California (USC) Keck School of Medicine found that exposure to a mixture of synthetic chemicals commonly found in the environment affects several critical biological processes – including fat and amino acid metabolism, in both children and adults. as well as young adults.

Disruption of these processes is associated with an increased risk of a wide variety of diseases, including developmental disorders, cardiovascular diseases, metabolic diseases and various types of cancer.

Perfluoroalkyl substances (PFAS) include thousands of synthetic chemical compounds that have numerous applications in various areas of life. PFAS are sometimes called “forever chemicals” because they break down very slowly and accumulate in the environment and human tissues.

While individual PFASs are known to increase the risk of several types of disease, this latest study is the first to report what biological processes are altered by exposure to a combination of multiple PFASs. This is important because in most cases a mixture of chemicals is present in the blood.

“Our findings were surprising and have broad implications for policy makers trying to reduce risk,” said Dr. Jesse A. Goodrich, assistant professor of population and public health sciences and lead author of the study. “We found that exposure to the combination of PFAS not only disrupted lipid and amino acid metabolism, but also altered the function of thyroid hormones,” he added.

To understand the effects of the PFAS mixture on the body, the researchers used blood samples taken from 312 participants in the At-Risk Hispanic Teen Study and 137 children in the Southern California Children’s Health Study. They found that all children and adolescents had a mixture of several commonly used PFASs in their blood, including PFOS, PFHxS, PFHpS, PFOA and PFNA. More than 98 percent of the participants also had PFDA in their blood.

At the same time, the researchers measured the levels of thousands of naturally occurring chemicals in the blood and, using a biostatistical method they developed, determined how exposure to many different PFASs affected each of these naturally occurring chemicals. Such information helped the researchers determine that exposure to PFAS changed the way the body metabolized lipids and amino acids, as well as thyroid hormone levels, an important determinant of metabolic rate.

The authors focused on children and young adults because these individuals go through critical developmental stages when they may be more susceptible to the adverse health effects of PFAS exposure. During this period of life, many serious diseases that manifest themselves in adults begin. The results are consistent with previous studies that showed that exposure to particular PFASs in childhood was associated with dysregulated lipid and fatty acid metabolism, which may increase the risk of metabolic disorders and cardiovascular disease later in life.

Particularly significant, according to the authors, was the effect of PFAS on the function of the thyroid hormone, which plays a key role in growth and metabolism, affecting the development of a child during puberty, which can have a significant impact on a number of diseases in later life, including diabetes, cardiovascular disease and cancer .

Nearly all US residents have detectable levels of several PFASs in their blood, which are found in a wide variety of products, including waterproof clothing and food packaging. An estimated 200 million people in the United States drink water with levels of PFAS far higher than those recommended by the U.S. Environmental Protection Agency in 2022.

Some manufacturers have phased out individual PFASs, but the authors of the study believe it would be important to regulate PFAS as a class of chemicals.

‘We’re really just beginning to understand the extent of the effects these chemicals have on human health,’ said Dr Leda Chatzi, professor of population and public health sciences and co-author of the study. ‘While interventions to date have focused on phasing out the use of individual PFASs such as PFOS and PFOA, our research shows why the focus should be on reducing exposure to all PFAS chemicals,’ she concluded.