PFAS, or per- and polyfluoroalkyl substances, is a collective term for a huge family of artificial chemicals. PFAS have been used in manufacturing for decades, but their use is increasingly being scrutinized. This is because more and more research studies are linking PFAS with serious health issues in both humans and animals. Moreover, they are known to accumulate in the environment and the body (this is sometimes called bioaccumulation). This has led to them getting the nickname Forever Chemicals. As a result, over the past 20 years there has been a drive by the chemical industry to find alternatives. Here, we look at why PFAS compounds are so widely used and how newer-generation PFAS chemicals are still posing challenges to human and environmental health.
Why are PFAS so widely used?
PFAS compounds have been widely used thanks to their unique properties. These include being resistant to water, grease, stains and heat. Typical domestic applications include nonstick cookware, waterproof clothing, stain resistant furniture, and even cosmetics. In industry, they are widely used for their resistance to other chemicals. This includes coatings on industrial and manufacturing materials, and even laboratory equipment and disposable materials. They are also found in pesticides, as reported in recent research.
PFAS first became popular in the 1950s and 1960s. These decades saw a significant shift in mass production. Plastics and manmade chemicals became the dominant materials in manufacturing. This is also the period when PFAS began to take off. Some of the earliest PFAS compounds were used to create nonstick pans for cooking.
The drive for PFAS replacements
By the 1990s, we had reached Peak PFAS. The compounds were found in almost anything you could imagine. PFAS were used to make shoes, carpets, and vehicle upholstery stain resistant. They were sprayed on clothing to make it water repellant, allowing water to bead and shed off more readily. Fast food packaging was coated with PFAS to make it grease resistant. That’s not to mention the thousands of uses in manufacturing and chemical industries. But already scientists were beginning to raise the alarm about the impacts on health and the environment. As a result, we started to see voluntary moratoriums on the use of specific PFAS compounds. Two compounds in particular gained notoriety: PFOA (Perfluorooctanoic acid) and PFOS (Perfluorooctanesulfonic acid). PFOA and PFOS are characterized by having long carbon chains with many fluorine atoms attached to the carbon atoms. They are often called long-chain PFAS compounds. These long carbon chains are thought in part to cause the persistence and difficulty in breaking down the molecules. So, the chemical industry reacted by phasing out these compounds and trying to find replacements with shorter carbon chains.
Eliminating the risks?
The biggest challenge they faced was to identify compounds that exhibit the same desired characteristics as traditional PFAS but are easier to break down in the human body. As an example, PFOA and PFOS have elimination half lives of 2-5 years. Elimination half life is a measure of how much time it takes for a compound to be removed from the body. If a compound has a half life of 2 years that means after 2 years, half of it is still in the body. And after 4 years a quarter is left. As a rule of thumb, scientists say that it takes five half-lives to effectively eliminate a chemical compound from the body. So, for many PFAS it takes 10-20 years for them to be eliminated.
GenX and other PFAS replacements
In the 2000s, DuPont began to search for a chemical that could directly replace PFOA. This resulted in GenX, the trade name for a chemical based on hexafluoropropylene oxide. Other companies followed suit, all trying to directly replace the so-called “legacy” PFAS compounds. In general, the resulting compounds are all short chain PFAS chemicals. The short-chain PFAS typically have 6 or fewer carbon atoms, whereas long-chain PFAS like PFOA and PFAS have 8.
The argument is that these compounds have the same desired properties as traditional PFAS, but they are broken down faster. As a result, people claim they are safer than the legacy long-chain PFAS chemicals. For instance, GenX (which has 5 carbon atoms) may have a half life of just a few days. So, if you are exposed to GenX it should be eliminated from your body in weeks. The problem is, the compound can still cause significant harm during that time. Moreover, with many toxic substances, the harm is caused by other compounds that are created while your body tries to eliminate the original chemical! All this means that, perhaps unsurprisingly, GenX and other short-chain PFAS chemicals are now also considered unsafe by many scientists.
Conclusions
Chemicals like GenX may have a shorter “half life” in the body, but they aren’t a silver bullet. There is mounting evidence that these compounds also cause health issues for humans and are extremely persistent in the environment. It may be that any compounds delivering the desirable properties of PFAS cause health issues. So, the PFAS problem isn’t going to go away any time soon. Meanwhile, all we can do is to undergo regular testing for PFAS and monitor the levels.
