Assessing Contaminants of Emerging Concern in the Great Lakes Ecosystem: A Decade of Method Development and Practical Application.

This article focuses on a decade-long, multiagency effort under the U.S. Great Lakes Restoration Initiative (GLRI) to assess the occurrence, ecological risks, and biological effects of contaminants of emerging concern (CECs) in the North American Great Lakes. Employing advanced chemical detection, new approach methodologies (NAMs), and integrated biological assessments across over 700 sites in approximately 200 tributaries, the project combined targeted and nontargeted analyses with laboratory and field studies on multiple aquatic species to prioritize contaminants and evaluate their impacts on ecosystem health. Key outcomes include development of improved sampling and modeling techniques, identification of priority chemicals (such as polycyclic aromatic hydrocarbons), and insights into the complex interactions of chemical mixtures affecting aquatic organisms. The work highlights ongoing challenges in ecological risk assessment of CECs and recommends further refinement of methods, expanded use of eco-focused NAMs, and consideration of combined stressors to support effective management and protection of Great Lakes ecosystems.