Are You Eating PFAS?

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​Pi-I Debby Lin, ScD, MS

Diet is an important modifiable risk factor for obesity. Although it is well-known that excess calories lead to weight gain, diet is beyond just counting calories. In nutrition, diet is the sum of food we consume. What we eat, when we eat, and how we eat all play a role in how our body takes in and uses energy.  

Figure 1: How can human be exposed to PFAS? (pictures reference) 

As food become more processed, we are not just consuming natural ingredients, but also food additives and other chemicals that unintentionally get into food sources. These can be chemicals that naturally occur in the environment or man-made chemicals, which could enter the food chain via contamination of crops, animals, other food source, or migrate from food contact materials during cooking, processing, and packaging. Many of these chemicals could be obesogens or “endocrine disruptors” which may increase fat cells, slow down metabolism, and alter the way the body manages hunger.
 
Our research team has been investigating a class of synthetical chemicals, per- and polyfluoroalkyl substances (PFAS) which has been linked with lower resting metabolic rate.
 
PFASs are prevalently found in the environment and in human blood; they are a group of more than 4000 chemicals with carbon-fluorine bonds that give desirable water-, grease-, and heat-resistant properties for industrial uses. They are used in many food-related products, such as non-stick cookware, food packaging, and food containers due to their water-, grease-, and heat-resistant properties. Testing of food containers and packaging materials found detectable levels of PFAS in molded fiber bowls, microwave popcorn bags, pizza boxes,  dessert and bread wrappers, and burger and sandwich boxes. PFAS can leach from containers into the environment and can also migrate to food upon contact (Figure 1).
 
The U.S. Food and Drug Administration (FDA) had performed PFAS testing in a diverse sample of food typically eaten by Americans as part of FDA’s Total Diet Study (TDS) and results showed 14 out of 91 food samples, collected in areas without known PFAS contamination, had detectable levels of PFAS. FDA’s safety assessment states these products were not likely to be health concerns at the level detected. Other testing of food collected from specific geographic areas with known environmental contaminations did find PFAS level in food that may be a potential health concern. Continuous surveillance of PFAS exposure in food and safety assessment are needed, and it is important to understand how human is exposed to PFAS from food. 

Figure 2. Our study found that diet high in vegetable, fruits and Omega-3 rich fish was associated with having lower blood concentration of PFAS (picture reference) 

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We recently published a paper examining dietary characteristics associated with blood concentrations of 6 PFAS chemicals among prediabetic adults in the US. Our study revealed people who consumed more high-fat and low-fiber bread/cereal/rice/pasta, which included fried rice, baked goods, enchiladas, tacos, nachos, corn bread, crackers, potato chips, corn chips, popcorns, and sweets/dessert had higher blood concentration of some PFAS. Consuming more meat/fish/shellfish (especially fried fish, but not Omega-3 rich fish) was also associated with higher plasma concentration of certain PFAS. We were not surprised by these finding because food groups of animal origin, especially seafood and shellfish, have been identified as the main dietary source of PFAS exposure. FDA’s TDS also found high levels of some PFAS in meat and chocolate cakes. 
 
Contamination of PFAS in ground water is also a major source of PFAS exposure. In our study, we did not have data on water consumption, but we did find people who drank more coffee and tea had higher concentrations of some PFAS, which could come from the water source, coffee beans/tea leaves, contact with container/cups, or from the brewing and preparation process.
 
Interestingly, even though trace level of PFAS had been previously reported in vegetable and fruit samples, the study participants who ate more vegetables did not have higher blood levels of PFAS. Instead, we found that a diet of vegetables, fruits and Omega-3 rich fish was associated with lower plasma concentrations of some PFAS, suggesting a healthier dietary habit might potentially influence absorption and elimination of PFAS. However, our analysis was cross-sectional so we cannot infer a causal relationship.  

From our study, we demonstrated that diet can influence exposure levels to environmental chemicals. When choosing what to eat, it is important to look beyond calories and nutrients. Public source, such as the NOVA food classification which provides information on food ingredients, food processing and food packaging, can be helpful in making us more cognizant about what we are eating!