New study links PFAS exposure and body weight regulation

Ryan O’Connell is a High Meadows Fellow

Perfluoroalkyl and polyfluoroalkyl substances (PFAS), sometimes referred to by the broader term “PFCs” (perfluorinated chemicals), are a large class of chemicals used to make products water- or grease-resistant. They can be found in everything from nonstick cookware and clothing to food packaging and adhesives. While PFAS have useful commercial and industrial applications, these chemicals also persist in the environment and in people, and a number of them have been shown to be very toxic.

Perfluorooctanoic acid (PFOA), perhaps the most infamous PFAS, has carcinogenic properties as recognized by authoritative bodies (see: here, here, and here). Other negative health outcomes associated with PFOA and other PFAS include increases in cholesterol, developmental effects in children, reproductive effects, endocrine disruption, and increases in cancer risk.

That is already a long list of serious health concerns. Yet a study published last week in PLOS Medicine suggests that we may need to add another health risk: interference with human weight regulation that may contribute to obesity. The study, a collaboration by researchers at Harvard T.H. Chan School of Public Health, Louisiana State University, and Tulane University, examines the relationship between exposure to certain perfluoroalkyl substances and changes in body weight and resting metabolic rate (RMR)—the amount of energy the body burns when at rest.

The authors of this new study used data from the two-year POUNDS (Preventing Overweight Using Novel Dietary Strategies) Lost trial, a clinical trial in which participants (overweight and obese men and women, ages 30-70) were prescribed controlled diets that restricted their daily caloric intake for weight reduction. The trial showed that weight loss occurred largely in the first 6 months, followed by 18 months of gradual weight regain.

Weight regain did not occur uniformly, however. As part of the study, the levels in participants’ blood of five specific PFAS, including both long- and short-chain perfluoroalkyl substances, were recorded. Researchers observed that the higher the blood levels of these PFAS were, the more weight was gained back after the initial period of weight loss.  Higher blood levels of these PFAS were also correlated with lower RMR values during the weight-regain period.

Taking these two associations together, the researchers propose that certain PFAS may contribute to weight gain by lowering the body’s resting metabolic rate, which decreases its energy burning capacity.

While the authors note that exactly how these PFAS exposures influence metabolic rate is not understood, they are clear about the study’s possible implications: “These findings suggest that environmental chemicals may play a role in the current obesity epidemic.”

The potential significance of this research is apparent when one considers that:

  • Biomonitoring studies routinely show that Americans have PFAS in their bodies.
  • PFAS enter our bodies from the food we eat and the water we drink; a recent Harvard study determined that PFAS levels in public drinking water sources serving six million people in the U.S. exceed federally recommended safety levels.
  • PFAS are known to persist in people and in the environment.

Unfortunately, we know little about the majority of PFAS, especially shorter-chain substances that are increasingly being used to replace the better-studied – and clearly risky – longer-chain substances within this class of chemicals. This puts us in the grim position of not understanding the risks these substances present until after they have been allowed in thousands of consumer products. For example, after approving their uses in food packaging for years, FDA just published a study showing that short-chain PFAS, like their long-chain counterparts, have the potential to biopersist in the body.

The need for more information on the risks and safety of chemicals, and the ability to address concerns when they arise, underscores the importance of having a strong and well-resourced EPA. Yet EPA’s proposed FY19 budget, just released by the Trump Administration, slashes the agency’s overall budget by 23% and its research budget by over 48%.

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