Engineered Nanomaterials as Emerging Contaminants in Water - Nanotechnologies for Water Environment Applications - page 559

16.2 What Are Emerging Contaminants?

Emerging contaminants in water can be defined as newly occurring materials of
concern, or materials which have been present for some time but not yet detected or
viewed as problematic. Recent history suggests that pollutants go through various stages
of concern over time (Figure 16.1). For example, pesticide use in the 1960's gave rise to
concern over their presence in water (Wauchope, 1978; Ritter, 1990). Rachel Carson
and others later began defining potential pesticide-related issues to the public, scientists
and engineering communities (Carson, 1962). Over time these groups formulated
potential solutions ranging from decreasing usage of some pesticides and developing
treatment strategies to minimize human and ecological exposure to pesticides. Passage
of various legislation by the United States Environmental Protection Agency (USEPA)
and other world-wide bodies attempted to balance human and ecological risks and
societal benefits from pesticides against mitigating treatment costs. Today, exposure to
pesticides has been significantly curtailed because of these actions. Pesticides serve as
an example for how pollutants move through various stages of concern over time as the
magnitude of the issue and potential solutions are identified. Pollutants may be
classified as “emerging contaminants” during the early phases of this evolution.

Pesticides Nutrients Trihalomethanes

Cryptosporidium Bromate EDC/PPCPs

Nanomaterials

1960 1970 1980 1990 2000 2010 2020 2030

Figure 16.1 Illustrative trends for various pollutants of concern. As the level of concern
changes the pollutant changes from an emerging contaminant to a well-defined one with
potential solutions identified and regulatory status assessed.