Reply for comment on "Transport and competitive interfacial adsorption of PFOA and PFOS in unsaturated porous media: Experiments and modeling'', published by GARZA-RUBALCAVA et al. [Water Research 268 (2025) 122728].

Chen and Li (2025) recently published a comment on Garza-Rubalcava et al. (2025) in which they claim that the predictions of chromatographic peaking described in that paper were due to an 'incorrect loop' in the MATLAB code accompanying the original manuscript. Here, we demonstrate that (1) the predicted chromatographic peaking of perfluorooctanoic acid (PFOA) observed in the experiments is the result of competitive adsorption at the air-water interface as captured by the model governing equations, and that (2) our simulator does not have an incorrect loop and can reliably predict the chromatographic peaking behavior observed in unsaturated column studies.

Molecular profiling of neuronal extracellular vesicles reveals brain tissue specific signals.

Extracellular vesicles (EVs) released by neurons (nEVs) provide an opportunity to measure biomarkers from the brain circulating in the periphery. No study yet has directly compared molecular cargo in brain tissue to nEVs found in circulation in humans. In 5 matched sets of brain tissue, serum, total EVs, and nEVs, obtained from the Bartoli Brain Tumor Laboratory at Columbia University, we compared the levels microRNAs and environmental chemicals because microRNAs are one of the most studied nEV cargoes and offer great potential as biomarkers and environmental chemical load in nEVs is understudied and could reveal chemical burden in the brain.

Incineration of Perfluorooctanoic Acid Leads to Regeneration of Smaller Perfluorocarboxylic Acids.

Perfluorooctanoic acid (PFOA) and other per and polyfluorinated alkyl substances (PFAS) are emerging environmental contaminants of concern. Incineration is a common method of PFAS destruction and disposal, but due to the strength and stability of C-F chemical bonds, the process is poorly understood. In the present work, we demonstrate that destruction of PFOA in a pilot-scale incinerator leads to a mixture of smaller perfluorocarboxylic acids (PFCAs).

Smoldering Treatment of PFAS: Investigation of Mass Balance and Volumetric Scale Up for Field Implementation.

The chemical properties of perfluoroalkyl and polyfluoroalkyl substances (PFAS) pose a significant remediation challenge. This study investigated smoldering combustion to destroy PFAS while scaling up from the lab to field implementation. The first phase consisted of bench-scale tests using a model soil system.

Gestational and Lactational Exposure to Perfluorohexanoic Acid Affects Behavior in Adult Male Mice: A Preliminary Study.

Legacy per- and polyfluoroalkyl substances (PFAS) have been associated with increased risk for male-biased neurobehavioral disorders. Industries have effectively replaced them with next-generation PFAS, including perfluorohexanoic acid (PFHxA). Zebrafish studies indicate developmental effects of PFHxA exposure on activity levels; however, the developmental neurotoxicology (DNT) of PFHxA has not been characterized in mammals.

Sorption-desorption processes contributing to natural attenuation of trichloroethene in porous media.

Monitored natural attenuation (MNA), which relies on natural processes to reduce contaminant concentrations over time, is widely used to manage dilute chlorinated solvent groundwater plumes. In heterogeneous aquifers, the accumulation and subsequent release of chlorinated solvents can strongly influence the long-term effectiveness of MNA. This research investigated rate-limited sorption-desorption processes influencing trichloroethene (TCE) release from lower-permeability media.

Remediation of groundwater contaminated with perfluoroalkyl acids and chlorinated ethenes using a microbial reductive dechlorination and sorptive material treatment train.

Groundwater contaminated by mixtures of perfluoroalkyl acids (PFAAs) and chlorinated ethenes (CEs) pose a significant remediation challenge due to the distinct characteristics of these two contaminant types. In situ adsorption barriers have been demonstrated as a promising remediation strategy for PFAA-contaminated groundwater plumes. However, most previous studies were carried out with only a single PFAA, and our understanding of the retention of comingled contaminant plumes, including multiple PFAAs and CEs in such barriers, remains limited.

Computational Investigation of the Reaction Mechanism for the Thermal Treatment of Hexafluoropropylene Oxide Dimer Acid (GenX).

Hexafluoropropylene oxide dimer acid (HFPO-DA, CFOCF(CF)C(O)OH), more commonly referred to as GenX, belongs to a category of environmental contaminants known as poly- and perfluoroalkyl substances. A detailed chemical kinetic mechanism was developed for the thermal destruction of GenX. The rate constants for the majority of the elementary reactions were computed using microcanonical rate theory and the master equation.

Sorption-desorption processes contributing to the natural attenuation of cis-1,2-dichloroethene in porous media.

Monitored natural attenuation (MNA) is widely used to manage groundwater plumes with persistent chlorinated solvents exceeding regulatory standards. In heterogeneous aquifers, accumulation and release of these contaminants can impact MNA's effectiveness. Research often focuses on tetrachloroethene (PCE) and trichloroethene (TCE), but incomplete reductive dichlorination can lead to cis-1,2-dichloroethene (DCE) accumulation.

Evaluation of co-foaming agents for enhanced removal of per-and polyfluoroalkyl substances (PFAS) by foam fractionation.

Foam fractionation has emerged as a leading method to remove per- and polyfluoroalkyl substances (PFAS) from impacted aqueous matrices due to the low cost and rapid PFAS removal. Although foam fractionation has been shown to efficiently remove long-chain PFAS, cationic co-foaming agents are often necessary to improve the removal of short-chain PFAS. However, many of the best performing co-surfactants used for short-chain PFAS removal, such as cetyltrimethylammonium bromide (CTAB), are of concern due to their potential toxicity and low biodegradability.

Prenatal PFAS exposures and cardiometabolic health in middle childhood in the MIREC cohort.

Studies on prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and cardiometabolic health in childhood have produced inconsistent results. In this study, we evaluated associations between prenatal PFAS exposures, individually and as a mixture, and cardiometabolic outcomes including insulin resistance, beta cell function, blood lipids, blood pressure and central adiposity during middle childhood (7-9 years of age) in a Canadian maternal-child cohort (n = 281). We also explored effect measure modification based on child sex and physical activity.

Modulation of blood-tumor barrier transcriptional programs improves intratumoral drug delivery and potentiates chemotherapy in GBM.

Efficient drug delivery to glioblastoma (GBM) is a major obstacle as the blood-brain barrier (BBB) and the blood-tumor barrier (BTB) prevent passage of the majority of chemotherapies into the brain. Here, we identified a transcriptional 12-gene signature associated with the BTB in GBM. We identified CDH5 as a core molecule in this set and confirmed its expression in GBM vasculature using transcriptomics and immunostaining of patient specimens.

Molecular profiling of neuronal extracellular vesicles reveals brain tissue specific signals.

Extracellular vesicles (EVs) released by neurons (nEVs) provide an opportunity to measure biomarkers from the brain circulating in the periphery. No study yet has directly compared molecular cargo in brain tissue to nEVs found in circulation in humans. We compared the levels microRNAs and environmental chemicals because microRNAs are one of the most studied nEV cargoes and offer great potential as biomarkers and environmental chemical load in nEVs is understudied and could reveal levels of chemicals in the brain.

Global metabolomic alterations associated with endocrine-disrupting chemicals among pregnant individuals and newborns.

Background: Gestational exposure to non-persistent endocrine-disrupting chemicals (EDCs) may be associated with adverse pregnancy outcomes. While many EDCs affect the endocrine system, their effects on endocrine-related metabolic pathways remain unclear. This study aims to explore the global metabolome changes associated with EDC biomarkers at delivery.

Covalently Cross-Linked Polyelectrolyte Complex Nanoparticles with Enhanced Stability against Dissociation at High Ionic Strength.

Polyelectrolyte complex nanoparticles (PECNPs) often fully dissociate into individual polycations (PC) and polyanions (PA) at high salinities. Herein, we introduce a novel type of colloidally stable PECNP in which the PC is cross-linked, in this case branched polyethylenimine (PEI) to limit this dissociation, even in solutions up to 5.2 M NaCl or 5.

Fate and Transformation of 15 Classes of Per- and Polyfluoroalkyl Substances in Aqueous Film-Forming Foam (AFFF)-Amended Soil Microcosms.

The environmental fate of per- and polyfluoroalkyl substances (PFAS) in aqueous film-forming foams (AFFFs), especially those synthesized by electrochemical fluorination (ECF) processes, remains largely unknown. This study evaluated the transformation of AFFF-derived ECF-based precursors in aerobic soil microcosms amended with a historically used AFFF formulation (3M Light Water). Fifteen classes of PFAS, including AFFF components and transformation products, were identified or tentatively identified by suspect screening/nontargeted analysis (SSA/NTA) throughout a 308-day incubation.

Transport and competitive interfacial adsorption of PFOA and PFOS in unsaturated porous media: Experiments and modeling.

Among emerging contaminants, per- and polyfluoroalkyl substances (PFAS) have captured public attention based upon their environmental ubiquity and potential risks to human health. Due to their typical surface release conditions and amphiphilic properties, PFAS tend to sorb to soil and accumulate at the air-water interface within the vadose zone. These processes can result in substantial plume attenuation.

Adsorption of per- and polyfluoroalkyl substances on biochar derived from municipal sewage sludge.

Granular activated carbon (GAC) and ion exchange resin (IXR) are widely used as adsorbents to remove PFAS from drinking water sources and effluent waste streams. However, the high cost associated with GAC and IXR generation has motivated the development of less expensive adsorbents for treatment of PFAS-impacted water. Thus, the objective of this research was to create an economically viable and sustainable PFAS adsorbent from sewage sludge.

Modulation of blood-tumor barrier transcriptional programs improves intra-tumoral drug delivery and potentiates chemotherapy in GBM.

Glioblastoma (GBM) is the most common malignant primary brain tumor. GBM has an extremely poor prognosis and new treatments are badly needed. Efficient drug delivery to GBM is a major obstacle as the blood-brain barrier (BBB) prevents passage of the majority of cancer drugs into the brain.

A randomized controlled trial of a housing intervention to reduce endocrine disrupting chemical exposures in children.

Few studies have considered household interventions for reducing endocrine disrupting chemical (EDC) exposures. We conducted a secondary analysis of a randomized controlled trial, originally designed to reduce lead exposure, to evaluate if the intervention lowered EDC exposures in young children. Study participants were children from the Cincinnati, Ohio area (n = 250, HOME Study).

High-Resolution Mass Spectrometry for Human Exposomics: Expanding Chemical Space Coverage.

In the modern "omics" era, measurement of the human exposome is a critical missing link between genetic drivers and disease outcomes. High-resolution mass spectrometry (HRMS), routinely used in proteomics and metabolomics, has emerged as a leading technology to broadly profile chemical exposure agents and related biomolecules for accurate mass measurement, high sensitivity, rapid data acquisition, and increased resolution of chemical space. Non-targeted approaches are increasingly accessible, supporting a shift from conventional hypothesis-driven, quantitation-centric targeted analyses toward data-driven, hypothesis-generating chemical exposome-wide profiling.

Repurposing Waste Chemicals for Sustainable and Durable Molecular Data Storage.

Molecular data storage offers the intriguing possibility of higher theoretical density and longer lifetimes than today's electronic memory devices. Some demonstrations have used deoxyribonucleic acid (DNA), but bottlenecks in nucleic acid synthesis continue to make DNA data storage orders of magnitude more expensive than electronic storage media. Additionally, despite its potential for long-term storage, DNA faces durability challenges from environmental degradation.

Using Network Analysis and Predictive Functional Analysis to Explore the Fluorotelomer Biotransformation Potential of Soil Microbial Communities.

Microbial transformation of per- and polyfluoroalkyl substances (PFAS), including fluorotelomer-derived PFAS, by native microbial communities in the environment has been widely documented. However, few studies have identified the key microorganisms and their roles during the PFAS biotransformation processes. This study was undertaken to gain more insight into the structure and function of soil microbial communities that are relevant to PFAS biotransformation.