Women in midlife exposed to combinations of perfluoroalkyl and polyfluoroalkyl substances (PFASs), dubbed "forever and everywhere chemicals", are at increased risk of developing diabetes, similar to the magnitude of risk associated with overweight, and even greater than the risk associated with smoking, new research shows.
"This is the first study to examine the joint effect of PFAS on incident diabetes," first author Sung Kyun Park, ScD, MPH, told Medscape Medical News.
"We showed that multiple PFAS as mixtures have larger effects than individual PFAS," said Park, of the Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor.
The results suggest that, "given that 1.5 million Americans are newly diagnosed with diabetes each year in the USA, approximately 370,000 new cases of diabetes annually in the US are attributable to PFAS exposure," Park and authors note in the study, published this week in Diabetologia.
However, Kevin McConway, PhD, emeritus professor of applied statistics, The Open University, UK, told the UK Science Media Centre: "[Some] doubt about cause still remains. Yes, this study does show that PFAS may increase diabetes risk in middle-aged women, but it certainly can't rule out other explanations for its findings."
Is There Any Way to Reduce Exposure?
PFASs, known to be ubiquitous in the environment and also often dubbed "endocrine-disrupting" chemicals, have structures similar to fatty acids. They have been detected in the blood of most people and linked to health concerns including pre-eclampsia, altered levels of liver enzymes, inflammation, and altered lipid and glucose metabolism.
Sources of PFAS exposure can run the gamut from nonstick cookware, food wrappers, and waterproof fabrics to cosmetics and even drinking water.
The authors note a recent Consumer Reports investigation of 118 food packaging products, for instance, which reported finding PFAS chemicals in the packaging of every fast-food chain and retailer examined, including Burger King and McDonald's, and even more health-focused chains such as Trader Joe's.
While efforts to pressure industry to limit PFAS in products are ongoing, Park asserted that "PFAS exposure reduction at the individual-level is very limited, so a more important way is to change policies and to limit PFAS in the air, drinking water, and foods, etc."
"It is impossible to completely avoid exposure to PFAS, but I think it is important to acknowledge such sources and change our mindset," he said.
In terms of clinical practice, the authors add that "it is also important for clinicians to be aware of PFAS as unrecognized risk factors for diabetes and to be prepared to counsel patients in terms of sources of exposure and potential health effects."
Prospective Findings From the SWAN-MPS Study
The findings come from a prospective study of 1237 women, with a median age of 49.4 years, who were diabetes-free upon entering the Study of Women's Health Across the Nation – Multi-Pollutant Study (SWAN-MPS) between 1999 and 2000 and followed until 2017.
Blood samples taken throughout the study were analyzed for serum concentrations of seven PFASs.
Over the study period, there were 102 cases of incident diabetes, representing a rate of 6 cases per 1000 person-years. Type of diabetes was not determined, but given the age of study participants, most were assumed to have type 2 diabetes, Park and colleagues note.
After adjustment for key confounders including race/ethnicity, smoking status, alcohol consumption, total energy intake, physical activity, menopausal status, and body mass index (BMI), those in the highest tertile of exposure to a combination of all seven of the PFASs were significantly more likely to develop diabetes compared with those in the lowest tertile for exposure (hazard ratio [HR], 2.62).
This risk was greater than that seen with individual PFASs (HR, 1.36-1.85), suggesting a potential additive or synergistic effect of multiple PFASs on diabetes risk.
The association between the combined exposure to PFASs among the highest versus lowest tertile was similar to the risk of diabetes developing among those who were overweight (BMI 25 - < 30 kg/m2) versus normal weight (HR, 2.89), and higher than the risk among current versus never smokers (HR, 2.30).
"Our findings suggest that PFAS may be an important risk factor for diabetes that has a substantial public health impact," the authors say.
"Given the widespread exposure to PFAS in the general population, the expected benefit of reducing exposure to these ubiquitous chemicals might be considerable," they emphasize.
The authors have reported no relevant financial relationships.
Diabetologia. Published April 11, 2022. Abstract