Forever chemicals and diabetes

What are forever chemicals?

PFAS (which stands for per- and polyfluoroalkyl substances) are called “forever chemicals” because these man-made substances persist in the environment. Produced worldwide since the 1940s, PFAS have water-repellent and grease-repellent properties and are widely used in thousands of products, such as nonstick cookware, food packaging, water- and stain-resistant clothing and carpets, dental floss, sunscreen, cosmetics, and firefighting foams and protective gear (1). Their chemical structure (strong carbon-fluorine bonds) makes it difficult for them to break down naturally, so they persist in the environment for decades to centuries. Over the years, they have accumulated in water, soil, air, and wildlife all over the world.

PFAS are detected in nearly half of U.S. tap water, in both municipal and private well water systems (2). Fish, seafood, and animal-derived foods such as eggs, dairy, and meat contain the highest levels of PFAS (3). The reasons for this include the phenomenon of biomagnification as PFAS travels up the food chain, polluted water, contaminated feed, and the fact that PFAS preferentially bind to proteins in the blood, liver, and other protein-rich tissues in animals. Plant-based foods generally have lower PFAS levels, because while plants can absorb PFAS from contaminated soil and irrigation water, their uptake is usually lower.

The Stockholm Convention on Persistent Organic Pollutants is a global treaty that aims to restrict and eliminate the use of these and other harmful chemicals that persist in the environment. Even though legacy “forever chemicals,” such as PFOA and PFOS, have been phased out of production since the early 2000s, they have not been completely eliminated and remain widely detected in the environment because of their persistence. What’s more, the emerging shorter PFAS (“short-chain” PFAS) that are designed to replace the legacy chemicals are now also widely detected in the environment and in human blood and urine samples in the U.S. (4) and globally (5), with the added problem that they are less well studied for their potential health harms and are unregulated.  

Harmful health effects of PFAS include reduced infant and fetal growth, high cholesterol levels, thyroid disease and dysfunction, immune dysfunction, liver dysfunction, ulcerative colitis, pregnancy-induced hypertension, and cancer (especially kidney, breast, and testicular), among others (1, 6, 7).

A good integrative medicine and functional medicine approach to health and disease prevention includes a mindful assessment of the potential exposures to environmental toxicants such as PFAS. Let’s now focus on what research shows for the relationship between PFAS and diabetes.

Research on exposure to forever chemicals and the risk of developing type 2 diabetes

Diabetes affects about 1 in 7 adults worldwide, up from 1 in 14 adults in 1990.

Several research studies have found an association between PFAS exposure and higher blood sugar levels and insulin resistance (8), which are the underlying cause of type 2 diabetes (see previous blog on the root cause of type 2 diabetes). Some studies have found no such association or even association in the opposite direction, but many of these studies were looking at lower PFAS blood levels and healthier populations (8).

Many studies have been done as well to investigate the association between PFAS and the development of type 2 diabetes (rather than just higher blood sugar levels and insulin resistance). Several studies have shown an association between PFAS exposure and a higher risk of type 2 diabetes (8).

For example, in a research study that followed initially non-diabetic individuals for 15 years, each doubling of the blood level of a PFAS measured at the beginning of the study was associated with a 14% higher risk of developing new-onset diabetes (9). Quite notably, such an increased risk was not seen in the group of study participants who were randomly assigned to an intensive lifestyle intervention that included diet and exercise. In other words, these results suggest that even though higher levels of PFAS in a person can increase their risk of developing diabetes, dietary and lifestyle changes could essentially erase the higher risk posed by their higher PFAS levels. This speaks to the power of lifestyle interventions in the prevention of diabetes.

(We already discussed in a previous blog that lifestyle intervention is more effective than metformin, a commonly prescribed diabetes medication, in preventing the new onset of type 2 diabetes, as demonstrated in a clinical trial published in the New England Journal of Medicine [10]).

It should be noted that some studies showed no such relationship between PFAS and diabetes, or a relationship in the opposite direction. However, in earlier studies on PFAS and diabetes, researchers typically examined individual PFAS separately, but in the real world, PFAS occur in mixtures in the environment. PFAS mixtures can produce effects that are greater than the sum of the individual PFAS effects and could have the potential for unexpected toxicity (8, 11). So, studies looking at realistic environmental PFAS mixtures, rather than single PFAS, can help us to better understand the real-world impact of these forever chemicals on the risk of developing type 2 diabetes (8). In a more recent study published in 2025, researchers investigated the relationship between a PFAS mixture (derived from statistical modeling) and type 2 diabetes (12). They found that higher exposure to the PFAS mixture was associated with higher odds of developing new-onset type 2 diabetes later on. When the study participants’ PFAS mixture levels were ranked from lowest to highest and divided into three groups (lowest, middle, highest), those in the middle group had a 31%-higher odds of developing type 2 diabetes compared with the lowest group, while those in the highest group had a 62%-higher odds of developing the disease compared with the lowest group.

There has been a rapid rise in the prevalence of type 2 diabetes in recent decades. Changes in the gene pool in the population can affect the prevalence of a disease in the population, but because gene pool changes take much longer and cannot account for the rapid rise in the prevalence of type 2 diabetes, discussions by experts have also focused on the role of environmental changes in the diabetes epidemic (13). Lifestyle changes, of course, play a role as well in the development of type 2 diabetes. More research into the relationship between exposure to PFAS (as well as other environmental toxicants) and diabetes is needed to better understand how environmental chemicals affect the risk of type 2 diabetes and the progression of this disease.

How can exposure to forever chemicals be reduced?

As pointed out by a report on PFAS by the National Academies of Sciences, Engineering, and Medicine (NASEM), it is possible to achieve changes in PFAS exposure at the population level when there are industry-wide changes in PFAS production. The report cited the example that PFAS concentrations in the U.S. decreased over time after the 3M company’s voluntary phase-out of certain PFAS (1), and the committee indicated, “Therefore, there is evidence that removing these chemicals from products on a large scale can result in lower levels in a population.”

The laws and regulations regarding PFAS in the U.S. are evolving constantly and vary widely at the state levels. Some states have been faster to respond. In 2018, New Jersey became the first state to set an enforceable low limit of PFAS in drinking water, for PFOA and PFOS. Several states, including New Jersey, have passed laws banning all PFAS in food packaging, taking effect in 2023-2024 (14).

Beyond the regulatory context, what can we do, at the individual level, for ourselves and our families, to reduce our exposure to forever chemicals?

For most people who do not have occupational exposures to PFAS, ingestion is the most well-studied route of exposure, which occurs when we drink contaminated water, eat contaminated seafood, or consume other contaminated foods (1). Reducing exposure from these sources is the most important step at the individual level.

Because contaminated drinking water is a significant source of PFAS exposure for most people, filtering water is an effective step in eliminating a significant portion of PFAS exposure, if water testing shows detectable levels of PFAS, but the type of filtration system matters. According to the NASEM report, which looked at prior research on various types and methods of water filtration (reverse osmosis, granulated activated carbon, single-stage, dual-stage), reverse osmosis and dual-stage filters were found to consistently remove most measured PFAS at an average of 90% or greater efficiency (1). Reverse osmosis systems have the most consistent and comprehensive PFAS removal across all chain lengths (in other words, both the legacy long-chain PFAS and the “emerging” short-chain PFAS designed to replace legacy PFAS) (15). Activated carbon filters vary in their effectiveness depending on the filter model and may have difficulty removing short-chain PFAS (16). There is also concern that when activated carbon systems are not properly maintained, they may even raise PFAS levels in purified water by releasing PFAS back into the water. In short, reverse osmosis systems are more effective than activated carbon filters in removing PFAS from drinking water.

Diet is another major source of PFAS exposure. Fish and seafood are associated with the highest level of exposure. In a study that examined global data, PFAS exposure from fish and seafood in several instances exceeded local safety thresholds (3). In general, foods of animal origin are the main dietary sources of PFAS exposure (3). Plant-based foods generally contain lower PFAS levels compared with animal-derived foods.

Other ways to reduce PFAS exposure, as recommended by an article in the New England Journal of Medicine, are to avoid packaged and highly processed foods, such as fast food, and to replace nonstick cookware with cookware made from nontoxic materials, such as stainless steel and ceramic (6).

PFAS can be found in cosmetics and personal care products. However, current research on skin absorption of PFAS is limited, so more data are needed to better understand how the use of PFAS-containing products may affect PFAS blood levels and health. A 2024 study found that forty PFAS ingredients were reported in cosmetics and personal care products sold in the U.S. (17). The personal care products in this study included hair care products, facial cleansers, lotions and moisturizers, shaving creams and gels, sun care products, and body washes. The most common PFAS ingredient reported was polytetrafluoroethylene (PTFE), present in almost all product subcategories in the study (17). Another study tested thirty-eight cosmetics and personal care products in Canada and detected PFAS in nearly all of them (99.7%) (18). One controlled human volunteer study showed that after applying PFAS-containing sunscreen to one 66-year-old male volunteer’s whole body, the volunteer’s blood levels of PFAS increased over days, reaching a peak after twenty-two days (19).

Research shows that PFAS can contribute to premature skin aging (20). Studies on

PFAS exposure through cosmetics are currently very rare (21). At this time, avoiding PFAS in cosmetics and skin care products is challenging. For those who are concerned about PFAS exposure through the skin, the following chemical names in the ingredient list indicate the presence of PFAS: polytetrafluoroethylene (PTFE), perfluorodecalin, and polyfluoroalkyl phosphate esters (PAPs), among others.

When it comes to products such as clothing, furnishings, and bedding, product labels rarely list chemical additives, including PFAS. In one study, of all the products tested, researchers found that PFAS was only detected in products advertised as water- and/or stain-resistant, though some water- and/or stain-resistant products had no detectable levels of the 16 PFAS tested in the study (22). Interestingly, “green” labels on these products did not seem to matter; PFAS was found as often in “green” products as non-“green” products. These data suggest that products without a water- and/or stain-resistant label are much more likely to have no PFAS.

At the industry level, there are potential alternatives to using PFAS in the manufacture of consumer products. One study identified 530 PFAS-free alternatives and concluded that potentially suitable alternatives are available for 40 applications (23).

What is the exposome and why is it important?

Forever chemicals and other environmental toxicants are part of the exposome, which is the totality of environmental exposures that contribute to health and disease. As a complement to the Human Genome Project, the Human Exposome Project is a global initiative to map and understand how environmental exposures shape human health. Researchers are hopeful that in the future, this research could transform the way clinicians practice.

An expert in the field said it well: “Environmental risk is real, it is complex, but most importantly, it’s modifiable. As clinicians, this is what we do. We try to change the environment of our patients—from dietary recommendations to lifestyle guidance to social health and even the medications we prescribe,” said Sinan Guloksuz, MD, PhD, an assistant professor at Yale University School of Medicine and an associate professor of psychiatry at Maastricht University in the Netherlands (24).

Such an ambitious and coordinated global endeavor as the Human Exposome Project affirms the visionary role of integrative medicine and functional medicine in shaping the future of medicine. The considerations of the exposome and the combined influences of a person’s environmental exposures have always been a fundamental part of the principles and practice of integrative medicine and functional medicine. As we look forward to such global advances in the study of the exposome, let’s apply what we already know to help ourselves heal now.

References

1. National Academies of Sciences, Engineering, and Medicine. Guidance on PFAS exposure, testing, and clinical follow‑up. Washington, DC: The National Academies Press; 2022.

2. Smalling KL, Romanok KM, Bradley PM, Morriss MC, Gray JL, Kanagy LK, et al. Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: Comparison of underserved private-well and public-supply exposures and associated health implications. Environ Int. 2023;178:108033.

3. Souza MCO, Domingo JL. Levels of per- and polyfluoroalkyl substances (PFAS) in foodstuffs: a review of dietary exposure, health risks, and regulatory challenges. Food Res Int. 2025;221(Pt 3):117494.

4. Zheng G, Eick SM, Salamova A. Elevated Levels of Ultrashort- and Short-Chain Perfluoroalkyl Acids in US Homes and People. Environ Sci Technol. 2023;57(42):15782-93.

5. Zhi Y, Lu X, Munoz G, Yeung LWY, De Silva AO, Hao S, et al. Environmental Occurrence and Biotic Concentrations of Ultrashort-Chain Perfluoroalkyl Acids: Overlooked Global Organofluorine Contaminants. Environ Sci Technol. 2024;58(49):21393-410.

6. Woodruff TJ. Health Effects of Fossil Fuel-Derived Endocrine Disruptors. N Engl J Med. 2024;390(10):922-33.

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8. Roth K, Petriello MC. Exposure to per- and polyfluoroalkyl substances (PFAS) and type 2 diabetes risk. Front Endocrinol (Lausanne). 2022;13:965384.

9. Cardenas A, Hivert MF, Gold DR, Hauser R, Kleinman KP, Lin PD, et al. Associations of Perfluoroalkyl and Polyfluoroalkyl Substances With Incident Diabetes and Microvascular Disease. Diabetes Care. 2019;42(9):1824-32.

10. Knowler WC, Barrett-Connor E, Fowler SE, Hamman RF, Lachin JM, Walker EA, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393-403.

11. Mahoney H, da Silva F, Brinkmann M, Giesy JP. Mixtures of legacy and replacement perfluorosulphonic acids (PFSAs) demonstrate ratio-, concentration- and endpoint-dependent synergistic interactions in vitro. Chemosphere. 2024;361:142446.

12. Midya V, Yao M, Colicino E, Barupal D, Lin X, Gennings C, et al. Exposure to per- and poly-fluoroalkyl substances in association to later occurrence of type 2 diabetes and metabolic pathway dysregulation in a multiethnic US population. EBioMedicine. 2025;118:105838.

13. Kahn SE, Cooper ME, Del Prato S. Pathophysiology and treatment of type 2 diabetes: perspectives on the past, present, and future. Lancet. 2014;383(9922):1068-83.

14. O'Sullivan Bakshi S, Dakin Z, Monaghan M, van Gerwen M. Per- and polyfluoroalkyl substances (PFAS) in the United States: Current knowledge and regulatory context. Sci Total Environ. 2025;1003:180711.

15. MacKeown H, Magi E, Di Carro M, Benedetti B. Removal of perfluoroalkyl and polyfluoroalkyl substances from tap water by means of point-of-use treatment: A review. Sci Total Environ. 2024;954:176764.

16. Iwabuchi K, Sato I. Effectiveness of household water purifiers in removing perfluoroalkyl substances from drinking water. Environ Sci Pollut Res Int. 2021;28(9):11665-71.

17. Balan SA, Bruton TA, Harris K, Hayes L, Leonetti CP, Mathrani VC, et al. The Total Mass of Per- and Polyfluoroalkyl Substances (PFASs) in California Cosmetics. Environ Sci Technol. 2024;58(27):12101-12.

18. Harris KJ, Munoz G, Woo V, Sauve S, Rand AA. Targeted and Suspect Screening of Per- and Polyfluoroalkyl Substances in Cosmetics and Personal Care Products. Environ Sci Technol. 2022;56(20):14594-604.

19. Abraham K, Monien BH. Transdermal absorption of (13)C(4)-perfluorooctanoic acid ((13)C(4)-PFOA) from a sunscreen in a male volunteer - What could be the contribution of cosmetics to the internal exposure of perfluoroalkyl substances (PFAS)? Environ Int. 2022;169:107549.

20. Mousavi SE, Delgado-Saborit JM, Godderis L. Exposure to per- and polyfluoroalkyl substances and premature skin aging. J Hazard Mater. 2021;405:124256.

21. Celine C, Catherine B, Romane C, Laurence C. Per- and polyfluoroalkyls used as cosmetic ingredients - Qualitative study of 765 cosmetic products. Food Chem Toxicol. 2024;187:114625.

22. Rodgers KM, Swartz CH, Occhialini J, Bassignani P, McCurdy M, Schaider LA. How Well Do Product Labels Indicate the Presence of PFAS in Consumer Items Used by Children and Adolescents? Environ Sci Technol. 2022;56(10):6294-304.

23. Figuiere R, Miaz LT, Savvidou E, Cousins IT. An Overview of Potential Alternatives for the Multiple Uses of Per- and Polyfluoroalkyl Substances. Environ Sci Technol. 2025;59(4):2031-42.

24. Anderer S. Beyond Genes: Human Exposome Project to Tackle External Drivers of Disease. JAMA. 2025;334(1):7-8.