This chapter comprehensively analyzes contaminants of emerging concern (CECs), highlighting their relevance to public health and environmental quality. These contaminants, including pharmaceuticals, personal care products, nanomaterials, and microplastics, present chemical complexity that demands detailed ecotoxicological assessments to understand and mitigate their adverse effects. Studies show how contaminants, such as antidepressants and silver nanoparticles, affect aquatic organisms and their trophic interactions, underscoring the need for science-based policies. The chapter emphasizes the importance of adaptive regulations and international collaboration to address the rapid introduction of new contaminants into the market. Antibiotic-induced bacterial resistance in the environment and endocrine disruptors’ impacts are risks that require practical regulatory actions. Public awareness through educational campaigns is vital to promote responsible behaviors and inform about the risks of CECs. Technological innovation is highlighted as crucial for waste remediation, with examples of bioremediation and advanced oxidation processes efficiently degrading persistent contaminants. Promoting sustainability involves replacing toxic substances with safer alternatives and creating circular production systems that minimize waste and maximize recycling. Finally, the chapter discusses the need for an interdisciplinary approach to tackle the challenges of CEC ecotoxicology, promoting the integration of knowledge from various scientific fields. Only through coordinated and continuous efforts will it be possible to protect the health of ecosystems and human communities, ensuring a safer and more sustainable future for future generations.