Prenatal PFAS exposure may be linked to childhood obesity, study shows

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About 1 in 5 U.S. children and adolescents have obesity, according to the CDC. (Photo credit: iStock by Getty Images)

Exposure in the womb to “forever chemicals” may be associated with a higher risk of obesity in 10-year-olds, especially females, a new study shows.

“The main result of the present study was that higher prenatal exposure to several PFAS was significantly associated with elevated BMI, anthropometric [body] measurements, and risk of obesity in children aged 10,” say the researchers, who observed more significant effects among girls. “However, our summary results suggest that the effects depend on the time of exposure and vulnerability. Any conclusions should be interpreted cautiously due to the small number of studies.”

About 1 in 5 U.S. children and adolescents have obesity, according to the CDC. The study, recently published in the October 2024 issue of Environment International, builds on growing evidence that PFNA and other harmful per- and polyfluoroalkyl substances (PFAS) can persist in the environment and our bodies, posing long-term health risks. PFAS are used in industrial products and everyday consumer items — from nonstick pans to shampoo, and much more.

It comes less than a year after researchers examining data from a long-term Boston-based study called “Project Viva” reported prenatal mixed PFAS exposures may lead to obesity in late adolescence at 16-20 years of age. Children with higher prenatal PFAS concentrations “had higher rates of BMI increase starting from 9–11 years of age,” that study found.

And last month, [September 2024], researchers in the Journal of Clinical Endocrinology & Metabolism warned that PFAS chemicals, which can cross the placenta, may cause pregnant women to experience long-term weight gain with more body fat than those with lower levels of exposure. That can increase the risk of conditions such as heart disease. 

The new study, led by Zhang Weng and colleagues at Fudan University in Shanghai, China, suggests two widely used chemicals — perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS)— may be primary contributors to the potential association of PFAS exposure and childhood obesity. (In the U.S., alternative PFAS replaced PFOA and PFOS.) PFOS is known for its former use in the fabric protector Scotchgard.

Other key chemicals include perfluorononanoic acid (PFNA), found in carpeting, stain-resistant furniture, and cleaning supplies.

“[Exposure] to higher levels of PFAS mixtures during pregnancy was associated with increased odds of obesity in girls, with PFNA emerging as the predominant driving compound,”  the study shows. Moreover, each doubling of PFNA concentration was “significantly associated” with increased weight and the risk of obesity in girls.

The team focused on data from 464 school-aged children, including 246 males and 218 females. The children and their mothers belong to a prospective birth cohort study (the Sheyang Mini Birth Cohort Study, SMBCS) established to assess over time whether pesticides and environmental pollutants lead to potential adverse physical growth and neurodevelopmental outcomes. 

Among other analyses, researchers looked at umbilical cord serum concentrations of 12 PFAS and urine samples from 10-year-olds. They also measured child weight, height, and other obesity-related indicators, including skinfold thickness (the amount of fat under the skin measured by special calipers) and waist and hip circumferences. Children with a body mass index (BMI) for age and sex were identified as obese, as defined by World Health Organization (WHO) guidelines.

The impact of environmental factors and behaviors such as breastfeeding and physical activities were taken into account, along with the large differences in physical growth between males and females.

The specific biological mechanism behind a potential association between PFAS exposure and obesity is unknown. In this study, Wang’s team underscores previous studies that have suggested changes in certain metabolic pathways (chemical processes that support body function) could play a role, but more research is needed. 

“Further studies on the mixture effects of multiple EEDs [environmental endocrine disruptors] are warranted to confirm these findings and toxicology tests are needed to investigate the underlying mechanisms,” they say.

References:

Wang, Zheng, et al. “Prenatal exposure to per- and polyfluoroalkyl substances and sex-specific associations with offspring adiposity at 10 years of age: Metabolic Perturbation plays a role.” Environment International, vol. 192, Oct. 2024, p. 109037, https://doi.org/10.1016/j.envint.2024.109037.

Extra reading:

Lerner, Sharon. “How 3M Executives Convinced a Scientist the Forever Chemicals She Found in Human Blood Were Safe” — ProPublica co-published with The New Yorker