A recent study suggests that exposure to a mixture of per- and polyfluoroalkyl substances (PFAS) may alter several critical biological processes, including the metabolism of fats and amino acids, which is associated with an increased risk of developmental disorders, cardiovascular disease, metabolic disease, and many types of cancer. Researchers also found that exposure to a mixture of PFAS may alter thyroid hormone function.

Although exposure to individual PFAS is already known to lead to negative health consequences, the present study is the first to evaluate how biological processes are altered by exposure to a combination of multiple PFAS, which is pertinent as humans are exposed to a mixture of PFAS. Also known as “forever chemicals,” PFAS have been widely used in consumer goods and packaging, leading to environmental contamination and subsequent human dietary exposure.

Researchers from the University of Southern California’s (USC’s) Keck School of Medicine analyzed blood samples collected from 312 participants during a study of Latino adolescents, as well as samples collected from 137 children during a USC children’s health study. All blood samples tested positive for a mixture of several common PFAS, including PFOS, PFHxS, PFHpS, PFOA, and PFNA. More than 98 percent of participants also had PFDA in their blood.

Next, using a biostatistical method developed in-house, the researchers measured how exposure to multiple PFAS impacts thousands of chemicals naturally present in human blood, revealing that PFAS exposure altered the way the body metabolized lipids and amino acids, as well as the levels of thyroid hormone, which greatly affects growth and metabolism. The disruption of thyroid hormone function during puberty may lead to diseases later in life such as diabetes, cardiovascular disease, and cancer. The present study focused on children and adolescents due to their increased susceptibility.

The researchers added that these results are consistent with earlier studies that showed exposure to individual PFAS in childhood was associated with dysregulated lipid and fatty acid metabolism, which can increase the risk of metabolic disorders and cardiovascular disease later in life.

Although some manufacturers have begun to phase out the use of individual PFAS, the study’s researchers conclude it is important to consider regulating PFAS as a class of chemicals.