Contaminants of Emerging Concern

‘Contaminants of emerging concern’ are often described as emerging contaminants or emerging pollutants, and some of them are indeed novel substances or materials, such as nanoparticles or new pharmaceuticals. Others though have been with us for decades (or longer) but our understanding of their effects is increasing, especially in combination and at low levels. They are often managed along with heavy metals, where the ill effects have been long understood. They include antiseptics, solvents, pharmaceuticals, pesticides, and personal care products. These chemicals may have substantial effects in trace levels in the aquatic environment; if similar effects become apparent for humans, that has implications for both water and wastewater treatment. A wide subset of law and policy, at international and national levels, is relevant for their management and this chapter provides an overview of some of the relevant regulation, in the context of rapidly developing science.