Childhood obesity: Are forever chemicals to blame?

Forever chemicals or per- and polyfluoroalkyl substances (PFAS) may increase risks of childhood obesity, and set kids up for health problems later in life.

A new study found that PFAS exposure changes young people’s metabolic processes, impacting how their bodies metabolize lipids and amino acids and altering thyroid hormone functions.^[] 

The researchers say their findings shed new light on how PFAS impacts children’s metabolic processes and may imply a need for PFAS screening at annual physical appointments.

The study was conducted by researchers at several schools of medicine and funded by the National Institutes of Health and the National Institute of Environmental Health Sciences. The researchers tested blood samples from 449 adolescents who had participated in the Study of Latino Adolescents at Risk or the Southern California Children’s Health Study.

The researchers measured PFAS levels in blood plasma and found that all samples contained mixtures of PFAS, including PFOS, PFHxS, PFHpS, PFOA, and PFNA. Using a high-resolution mass-spectrometry metabolism method to measure about 10,000 metabolites in the samples, the results showed that the chemicals affected multiple biological pathways responsible for diseases, says Lida Chatzi, MD, Ph.D., study author and professor of population and public health sciences at the Keck School.

“The study included two independent cohorts—one cohort of teenagers in the Hispanic population at risk for developing type 2 diabetes; the other a cohort of young adults,” says Chatzi. “Both cohorts confirmed the original hypothesis—the proof of causality.”

PFAS impact on metabolism

Previous research has noted a connection between PFAS and thyroid health in adults. The study adds to the literature by highlighting how chemicals can harm adolescent thyroid function, too. 

“In kids, this hasn’t been established before,” says Jesse A. Goodrich, PhD, lead author of the study and assistant professor of population and public health sciences at the Keck School. “The fact that PFAS are impacting thyroid hormone is really important because thyroid hormone is one of the key determinants of metabolism that is necessary for normal development during puberty.” 

The study found a positive association between PFAS and B-4, the primary thyroid hormone, in adolescents,^[] says Chatzi. It’s important to look further into this connection, as issues with the thyroid can roll over to problems with weight management or put children at risk for other conditions later in life, she adds.

“The effect of PFAS on the thyroid hormones could perhaps explain their associations with multiple other diseases—from obesity to type two diabetes to cancer to liver disease,” says Chatzi.

As such, forever chemicals could be more harmful than even the study shows, and more investigations are needed to define the breadth of PFAS-based health risks.

Research needed on prevention, treatment

Staying safe from PFAS requires a mixture of prevention and intervention—neither of which is easy.

On the prevention side, the researchers say children and adults should avoid the chemicals where possible. But unfortunately, PFAS are found in a wide range of products—from fire extinguishers to cooking materials, food packaging to rain jackets, cosmetics, to period underwear. Further, most manufacturers are not required to test products for PFAS, so even people actively trying to avoid the chemicals can be blindly exposed.

Classifying PFAS on a group basis

PFAS prevalence makes it more likely that people can be impacted by a group of chemicals than one particular culprit. The researchers argue that the chemicals should be classified as a whole class, rather than name-by-name, to be more effectively phased out by future legislation.

The researchers were nuanced in their approach of looking at the risks of multiple PFAS together, as past studies have more commonly isolated one chemical. 

“The combination of these exposures may actually affect us differently than just a single exposure by itself," says Goodrich. “We should probably start thinking about regulating more as a chemical class as opposed to just a chemical by chemical basis which is currently the approach that's being taken.”

Environmental work groups like the Green Science Policy Institute, which was not affiliated with the study, advocate for phasing out multiple PFAS. The institute educates people on PFAS health risks and advocates for clean alternatives.

“Evidence is growing that the widespread use of forever chemicals is setting our kids up for health problems,” says Rebecca Fuoco, Director of Science Communications at the Green Science Policy Institute. “The kicker is that many uses of these chemicals are unnecessary. We need to phase out all non-essential uses of the whole class of PFAS as soon as possible.”

“We're moving towards the ability to potentially measure both environmental exposures and these metabolites in blood to be able to give more of a precise risk profile, and understand an individual's risk for different diseases,” says Goodrich. “With that information, you can maybe implement different preventative measures–preventative lifestyle measures.”

Asking people about the products they use and their risk for PFAS exposure could also be added to questioning, as part of standard clinical practice, says Chatzi.

“We ask people: ‘What's your diet? Do you smoke? Where do you live?” says Chatzi. “But we need to incorporate more environmental exposures in the screening for annual physicals.”