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Decoding the metabolic blockade effect: PFAS inhibition of organic anion transporters impairs VOC clearance and amplifies neurocognitive decline
Summary
Using a double machine learning framework on NHANES data, this study found that long-chain PFAS (particularly PFNA) competitively block renal excretion of VOC metabolites by binding organic anion transporter OAT1 with higher affinity than the metabolites themselves, amplifying neurocognitive decline by up to 1.5-fold. These findings establish a mechanistic synergy between two widespread environmental contaminants, directly relevant to microplastic research as PFAS are commonly found adsorbed onto microplastic particles, raising concern about combined toxicity.
Abstract The co-occurrence of per- and polyfluoroalkyl substances (PFAS) and volatile organic compounds (VOCs) in industrial environments poses complex toxicological risks that standard additive models fail to capture. This study elucidates a novel “metabolic blockade” mechanism wherein PFAS competitively inhibits the renal excretion of VOC metabolites, thereby amplifying neurotoxic burdens. Utilizing a Double Machine Learning (DML) framework on data from National Health and Nutrition Examination Survey (2005–2020), we analyzed a final intersectional cohort of 1,975 participants. We identified a robust inhibition of VOC metabolite clearance by serum PFAS. Specifically, PFNA significantly suppressed the excretion of the benzene metabolite URXPMA (Causal β TMLE = −0.219, p < 0.001), with efficacy dependent on perfluorinated chain length. Molecular docking simulations revealed the biophysical basis of this antagonism: long-chain PFNA exhibited superior binding affinity to the Organic Anion Transporter 1 (OAT1) (Δ G = −6.333 kcal/mol) compared to native VOC metabolites (Δ G = −4.957 kcal/mol), confirming high-affinity competitive inhibition at the renal interface. In a neurocognitive sub-cohort (N = 1,200), this interference translated into functional synergism; high-PFNA exposure magnified VOC-associated cognitive impairment by 1.5-fold and significantly exacerbated the negative association between VOC burden and processing speed ( β int = −0.263, p = 0.004). These findings define PFAS as a “metabolic amplifier” of co-contaminant toxicity, necessitating a paradigm shift toward mixture-based hazardous material regulations that account for transporter-level interactions.