Contaminants of emerging concern (CECs) is a term used by water quality professionals to describe pollutants that have been detected in environmental monitoring samples, that may cause ecological or human health impacts, and typically are not regulated under current environmental laws. Sources of these pollutants include agriculture, urban runoff and ordinary household products (such as soaps and disinfectants) and pharmaceuticals that are disposed to sewage treatment plants and subsequently discharged to surface waters. Examples of emerging contaminants are 1,4-Dioxane, food additives, pharmaceuticals, and natural & synthetic hormones. CECs have the ability to enter the water cycle after being discharged as waste through the process of runoff making its way into rivers, directly through effluent discharge, or by the process of seepage and infiltration into the water table, eventually entering the public water supply system. Emerging contaminants are known to cause endocrine disrupting activity and other toxic mechanisms, some are recognized as known carcinogens by the United States Environmental Protection Agency (EPA). General problem For a compound to be recognized as an emerging contaminant it has to meet at least two requirements: Adverse human health effects have been associated with a compound. There is an established relationship between the positive and negative effect(s) of the compound. Emerging contaminants are those which have not previously been detected through water quality analysis, or have been found in small concentrations with uncertainty as to their effects. The risk they pose to human or environmental health is not fully understood. Contaminant classes Contaminants of emerging concern (CECs) can be broadly classed into several categories of chemicals such as pharmaceuticals and personal care products, cyanotoxins, nanoparticles, and flame retardants, among others. However, these classifications are constantly changing as new contaminants (or effects) are discovered and emerging contaminants from past years become less of a priority. These contaminants can generally be categorized as truly "new" contaminants that have only recently been discovered and researched, contaminants that were known about but their environmental effects were not fully understood, or "old" contaminants that have new information arising regarding their risks. Pharmaceuticals Pharmaceuticals are gaining more attention as CECs because of their continual introduction into the environment and their general lack of regulation. These compounds are often present at low concentrations in water bodies and little is currently known about their environmental and health effects from chronic exposure; pharmaceuticals are only now becoming a focus in toxicology due to improved