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PFAS are dangerous! Oh, and the sky is falling! Has the media overreacted to these chemicals? Here’s what you need to know.
PFAS (per- and poly-fluoroalkyl substances) are a group of chemicals often called “forever chemicals” because they stubbornly refuse to break down. They’ve lately garnered a lot of attention from various media outlets because they’re seemingly the cause of just about all society’s problems. Heck, even T Nation sounded an alarm about them.
There’s certainly some evidence to suggest that these chemicals can cause harm at high enough concentrations. But there’s also a great deal of observational data showing correlations with all sorts of endpoints that, rather than showing true evidence of harmful effects, may simply reflect that PFAS levels are a good marker for general health (more on that later).
This is inherently the problem with observational research. First, despite all the recent attention, PFAS aren’t a new group of chemicals (1). They’ve been around since the 1940s, and humans have been exposed to these compounds for about 70 years.
They’re present in various products that most people use in their homes: paper and cardboard packaging, Teflon coating, Scotchgard, cosmetics, and the list goes on. The two most widely known are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).
They’re also commonly used in building materials. Given their widespread use and their persistence in the environment (in the air, dust, water, and soil), they’ll continue to be found in our bodies for a long time to come (1).
However, blood levels of PFOA and PFOS have been greatly declining in the U.S. population since manufacturers have begun phasing them out of products.
While epidemiological studies show an association between these chemicals and cardiovascular disease and all-cause mortality, there are also associations between disease/death and terrible lifestyle choices. That may be confounding the association between PFAS and kicking the bucket.
For example, fast food, pizza, microwave popcorn, ice cream, soda, fried (not omega-3 rich) fish, candy, salad dressing, butter, cheese, and white rice have positive associations with PFAS levels (1-5). However, eating at home shows an inverse association with PFAS levels, while going out for fast food is associated with a higher level (2).
Those eating a diet in omega-3-rich fish, fiber, fruit, and vegetables also show lower PFAS levels (4), while consuming a diet rich in fried fish, low-fiber foods, and high-fat bread/cereal/rice/pasta was associated with higher PFAS plasma concentrations (4).
This begs the question: Are at least some of these proposed adverse effects of PFAS simply confounded by the fact that lifestyle choices known to improve health are associated with lower PFAS exposure, while unhealthy choices are associated with higher PFAS exposure?
It’s not surprising given that PFAS are found in fast food containers and packaging, non-stick paper, pizza boxes, and plastic used for various foods (butter, microwave popcorn, ice cream, candy) (6).
One group of researchers speculated that spending more time indoors could lead to adverse health effects. The adverse effects presumably weren’t due to the lack of any physical activity and being sedentary but due to the exposure to PFAS from the carpet and couch (5).
That seems like a stretch. I can’t help but think we’ve become too accustomed to blaming various chemicals for many of our preventable disease states when diet and physical activity (or lack thereof) are really to blame.
One telling study followed overweight and obese adults assigned to either a placebo group (they received only information on diet and exercise) or an interventional group (they received training in diet, physical activity, and behavior modification with goals of achieving 7% weight loss and maintenance of 150 minutes of weekly physical activity) over 15 years (7).
The results weren’t particularly surprising. Those in the interventional group failed to have any association between PFAS and weight gain. In other words, even with elevated PFAS levels, there was no association with weight gain.
However, those in the placebo group did show an association between PFAS and weight gain. The authors concluded that PFAS might act as obesogens – compounds capable of inducing or increasing the likelihood of getting fat – but changes in diet and exercise can attenuate their effects. I guess that’s one interpretation. Another interpretation, perhaps more plausible, is that obesity, in this case, isn’t chemically induced but is modifiable with diet and exercise.
Exercise and eating fruits and vegetables are powerful modifiers that decrease the risk of all-cause mortality and cardiovascular disease (8-14), yet it seems that PFAS often end up taking the blame. These seemingly myopic researchers aren’t bothering to consider these factors, not to mention the role a sedentary lifestyle and poor diet can play in getting sick and dying.
No, it seems that PFAS may be more of a bystander, guilty through association rather than an actual cause of obesity and various diseases.
While it’s true that most studies evaluating the association between PFAS and various diseases adjust for BMI, physical activity, and diet, this doesn’t rule out residual confounding or unmeasured confounding. We must also consider the reliability of whichever source is being relied upon for these estimates – self-reported data for exercise and diet may be inaccurate. This may bias results and cause inadequate adjustment for confounding (15).
By all means, avoid PFAS-containing items as much as you can. It certainly can’t hurt, but don’t let the constant media attention scare you.
Continue living a healthy lifestyle and maybe consider a top-of-the-line water filtration system, but try not to sweat the rest. Many of the associations between PFAS levels and many diseases probably aren’t due to PFAS itself but confounders, including physical activity and diet.
This makes the presence of high levels of PFAS a good indicator of poor health, but perhaps not the cause of it. Conversely, the lack of high levels might indicate the good health that results from exercise and a good diet that’s coincidentally related to a low intake of PFAS.
Individuals with extreme occupational exposure to PFAS or near sites of known contamination warrant the most concern. But it’s not worth losing sleep over for the rest of us.
Gaines LGT. Historical and current usage of per- and polyfluoroalkyl substances (PFAS): A literature review. Am J Ind Med. 2022 May 25. doi: 10.1002/ajim.23362. Epub ahead of print. PMID: 35614869.
Susmann HP, Schaider LA, Rodgers KM, Rudel RA. Dietary Habits Related to Food Packaging and Population Exposure to PFASs. Environ Health Perspect. 2019 Oct;127(10):107003. doi: 10.1289/EHP4092. Epub 2019 Oct 9. PMID: 31596611; PMCID: PMC6867167.
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