Contaminants of Emerging Concern, With an Emphasis on Nanomaterials and Pharmaceuticals

Contaminants of emerging concern (CECs) include a diversity of compounds, categorized as “emerging” because they are currently not monitored or regulated. However, these chemicals have the potential to accumulate in the environment and may cause adverse effects to humans or wildlife. Despite their emerging status, we can apply basic toxicological principles to understand their fate, transport, and bioavailability, and new approaches (i.e., adverse outcome pathways) to understand their environmental impacts. This chapter focuses on nanomaterials and pharmaceuticals as case studies to illustrate the challenges associated with CECs. Nanomaterials may have complex macromolecular structures and often display increased reactivity compared with their bulk counterparts. Pharmaceuticals are potent by design and often cause adverse effects to aquatic life at very low concentrations. We propose that by understanding the reasons why some chemicals are CECs, green chemists can play an important role by designing less toxic chemicals with limited persistence and thus reduce the number of CECs in the environment.