Abstract Chemical safety evaluations are shifting to incorporate alternative methods (e.g., in vitro and in silico approaches) to meet demand for rapid, efficient chemical hazard assessments for human health and ecological impacts. Historically, toxicity results from in vitro exposures were not candidates for inclusion in the U.S. EPA’s ECOTOXicology Knowledgebase (ECOTOX). ECOTOX is the world’s largest compilation of curated ecotoxicity data for aquatic and terrestrial organisms, providing support for ecological chemical assessments through identification and curation of toxicity results. Presented here is ECOTOX’s recent expansion to incorporate in vitro studies of chemical ecotoxicity using well-established ECOTOX systematic literature review procedures. Since 2017, in vitro ecotoxicity data from over 575 publications were added to the public website (www.epa.gov/ecotox), with cell, tissue, and/or enzyme exposures from 310 species, including fish, amphibians, reptiles, birds, mammals, plants, algae, and invertebrates. Here we summarize in vitro ecotoxicological data available, identify where in vitro data are currently lacking for research and risk assessment, and demonstrate application of ECOTOX in vitro data in adverse outcome pathway development. This in vitro expansion continues and will evolve to support study quality evaluations and validation of new approach methodologies, necessary components for strengthening evidence certainty and furthering application of alternative approaches in regulatory frameworks.
Abstract Inland shipping is a critical source of volatile organic compounds (VOCs), but emission inventories rely on spatially averaged load factors that fail to capture localized transient events. We addressed this gap through an 800-km high-frequency mobile measurement campaign along the Yangtze River. The observations revealed a striking spatial anomaly: the most intense pollution hotspots (>50 ppbV) were spatially decoupled from the high-traffic Wuhan megacity, clustering instead within the remote, sinuous Jingjiang channel. Chemical forensics explicitly ruled out topographical trapping. Unlike steady cruising plumes, these hotspots exhibited exceptionally high toluene-to-benzene ratios (∼13.0) and enriched unburned fuel tracers. High-frequency GPS tracking confirmed that this distinct fingerprint is driven by a 4.2-fold increase in vessel speed fluctuation variance, proving that hydrodynamic resistance in tortuous channels compels vessels into inefficient transient combustion regimes. We conclude that navigational complexity acts as an invisible stressor creating localized pollution risks evaded by regional traffic-based models.
Abstract Field observations at geological CO2 storage sites, including the Otway International Test Centre (OITC), report rapid plume migration, potentially driven by highly channelized flow pathways caused by small-scale heterogeneities. However, how small-scale heterogeneities govern upscaled flow behavior, particularly the role of fluid connectivity, remains unclear due to imaging resolution limitations. To address this, we combined steady-state core-flooding experiments with micro-CT imaging (10 μm resolution) to directly visualize CO2 distribution for a heterogeneous core from OITC. Strong flow channelization was observed, leading to low core-average CO2 saturations. CO2 connectivity increased at the expense of brine connectivity over a narrow saturation interval, leading to steep brine relative permeability curves. A simple reservoir model was used to demonstrate that our derived relative permeability functions produce faster lateral CO2 plume migration and improved pore-space utilization. This work provides a foundation for improving relative permeability parametrization in reservoir simulations, aiding safe and efficient CO2 storage design.
