Certain highly pervasive environmental pollutants may have a variety of negative effects on kidney health, according to an analysis of all relevant studies published on this topic to date.
In the Clinical Journal of the American Society of Nephrology analysis, researchers assessed studies on per- and polyfluoroalkyl substances (PFAS), which are a large group of manufactured non-biodegradable compounds used to provide stain and grease repelling properties to consumer products including textiles, papers, and food packaging. PFASs are also used in aqueous fire-fighting foams. Recently, they have been detected on military bases, as well as in public water supplies from industrial contamination and in agricultural and crop products.
Because PFASs have been detected in soil, air, and water from all regions of the world, with bioaccumulation across entire ecological food chains, the compounds are now recognized as globally ubiquitous pollutants.
“The kidneys are very sensitive organs, particularly when it comes to environmental toxins that can get in our bloodstream,” said John Stanifer, MD, a nephrologist and clinical researcher at Duke University. “Because so many people are now exposed to these PFAS chemicals, and to the newer, increasingly produced alternative PFAS agents such as GenX, it is critical to understand if and how these chemicals may be contributing to kidney disease.”
Dr. Stanifer and his colleagues systematically searched PubMed, EMBASE, EBSCO Global Health, World Health Organization Global Index, and Web of Science for studies from 1990 to 2018 on the epidemiology, pharmacokinetics, or toxicity of PFAS exposure and kidney-related health.
In the 74 studies identified (21 epidemiologic, 13 pharmacokinetic, and 40 toxicological studies), there were many adverse outcomes linked to PFAS exposure, including worse kidney function and dysregulated pathways linked to kidney disease. Those dysregulated pathways include oxidative stress pathways, peroxisome proliferators-activated receptor pathways, and NF-E2-related factor pathways.
Toxicology studies showed tubular histological and cellular changes from PFAS exposure, and pharmacokinetic studies demonstrated that the kidneys are the major routes of elimination.
“By searching all the known studies published on the topic, we concluded that there are several potential ways in which these chemicals can cause kidney damage,” said Dr. Stanifer. “Further, we discovered that there have already been multiple reports suggesting that these chemicals are associated with worse kidney outcomes.”
Fan Fan Hou, MD, PhD, a researcher at Southern Medical University, in Guangzhou, China, noted that the findings add to previous studies on PFAS compounds.
“The increase in environmental pollution, a result of accelerated industrialization and urbanization worldwide, has become a global health challenge. Although there is evidence for the association between exposure to PFAS and kidney cancer, the impacts of PFAS exposure on non-cancer kidney outcomes are inconclusive,” said Dr. Hou, who was not involved with this research. “Large prospective cohort studies with accurate exposure measurement and long follow-up period are required to better understand the renal adverse effect of PFAS.”
Disproportionate effect on children, ethnic and racial minorities
Experts also stress that it is concerning that children are exposed to PFAS agents to a greater extent than adults. Life-course studies will be critical to understand the long-term health impact of this exposure.
“The study of the kidney effects of perfluorinated chemicals is especially relevant in pediatrics,” said Howard Trachtman, MD, who is a pediatric nephrologist at NYU Langone Health. “Because of the persistence of these chemicals in the body for extended periods of time and the association between exposure and reduced GFR that we have documented in healthy pediatric participants in NHANES, children and adolescents may be especially vulnerable to the adverse renal consequences of exposure to perfluorinated chemicals over a lifetime.”
Environmental risk factors contribute to the development and perpetuation of health disparities around the world, Dr. Langone and his team noted. Contaminants have been linked to higher burdens of chronic diseases and cancers, maternal and neonatal mortality, and developmental toxicity. Dr. Langone was not involved with the study.
Studies are needed to understand the role that environmental exposure to PFAS chemicals may play in driving kidney disease disparities, Dr. Langone said.
“Chronic kidney disease, which affects more than 30 million people in the United States and more than 500 million people across the world, disproportionately burdens ethnic and racial minorities and people living in poverty; yet exactly what causes these disparities is not fully known,” he said.
