Impact of kidney hyperfiltration on concentrations of selected perfluoroalkyl acids among US adults for various disease groups

A State-of-the-Science Review of Interactions of Per- and Polyfluoroalkyl Substances (PFAS) with Renal Transporters in Health and Disease: Implications for Population Variability in PFAS Toxicokinetics

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment and have been shown to cause various adverse health impacts. In animals, sex- and species-specific differences in PFAS elimination half-lives have been linked to the activity of kidney transporters. However, PFAS molecular interactions with kidney transporters are still not fully understood. Moreover, the impact of kidney disease on PFAS elimination remains unclear.

OBJECTIVES

This state-of-the-science review integrated current knowledge to assess how changes in kidney function and transporter expression from health to disease could affect PFAS toxicokinetics and identified priority research gaps that should be addressed to advance knowledge.

METHODS

We searched for studies that measured PFAS uptake by kidney transporters, quantified transporter-level changes associated with kidney disease status, and developed PFAS pharmacokinetic models. We then used two databases to identify untested kidney transporters that have the potential for PFAS transport based on their endogenous substrates. Finally, we used an existing pharmacokinetic model for perfluorooctanoic acid (PFOA) in male rats to explore the influence of transporter expression levels, glomerular filtration rate (GFR), and serum albumin on serum half-lives.

RESULTS

The literature search identified nine human and eight rat kidney transporters that were previously investigated for their ability to transport PFAS, as well as seven human and three rat transporters that were confirmed to transport specific PFAS. We proposed a candidate list of seven untested kidney transporters with the potential for PFAS transport. Model results indicated PFOA toxicokinetics were more influenced by changes in GFR than in transporter expression.

DISCUSSION

Studies on additional transporters, particularly efflux transporters, and on more PFAS, especially current-use PFAS, are needed to better cover the role of transporters across the PFAS class. Remaining research gaps in transporter expression changes in specific kidney disease states could limit the effectiveness of risk assessment and prevent identification of vulnerable populations. https://doi.org/10.1289/EHP11885.

The Relationship between Typical Environmental Endocrine Disruptors and Kidney Disease

Endocrine disrupting chemicals (EDCs) are exogenous substances that alter the endocrine function of an organism, to result in adverse effects on growth and development, metabolism, and reproductive function. The kidney is one of the most important organs in the urinary system and an accumulation point. Studies have shown that EDCs can cause proteinuria, affect glomeruli and renal tubules, and even lead to diabetes and renal fibrosis in animal and human studies. In this review, we discuss renal accumulation of select EDCs such as dioxins, per- and polyfluoroalkyl substances (PFAS), bisphenol A (BPA), and phthalates, and delineate how exposures to such EDCs cause renal lesions and diseases, including cancer. The regulation of typical EDCs with specific target genes and the activation of related pathways are summarized.

Associations between serum PFOA and PFOS levels and incident chronic kidney disease risk in patients with type 2 diabetes

Chronic kidney disease (CKD) is a common comorbidity among patients with type 2 diabetes. Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) has been linked to poorer kidney function in general population, but the related studies in individuals with diabetes were very limited. We aimed to examine the longitudinal associations of PFOA and PFOS exposure and CKD incidence among diabetes patients. Baseline levels of PFOA and PFOS were measured in serum in 967 diabetes patients from the Dongfeng-Tongji cohort. Multivariable logistic regression models were used to characterize the relationship between serum PFOA and PFOS levels and incident CKD risk (defined as estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m²). During 10-years follow-up, 267 incident CKD cases were identified. Only PFOS level was significantly associated with lower risk of CKD incidence (adjusted OR: 0.67; 95%CI: 0.51, 0.88). Such inverse association was only observed among participants with lower eGFR levels (< 70 mL/min/1.73 m²), although the interaction did not achieve statistical significance. Notably, an inverted U-shaped relationship between eGFR and serum PFOS level (P_{for nonlinearity} < 0.001) was observed based on the 1825 subjects with available data at baseline. PFOS exposure was negatively associated with CKD incidence in patients with diabetes, especially in those with baseline eGFR levels < 70 mL/min/1.73 m². This may be explained by the implication of baseline kidney function on the serum PFAS concentrations which in turn affect the relationship between PFOS exposure and the incident CKD risk among diabetes.