Analysis of Emerging Contaminants in Drinking Water – A Review

Analytical laboratories can now identify and quantify an impressive number of pollutants at very low concentrations in drinking water. Many of these chemicals are currently not analyzed routinely and, as such, are deemed ‘emerging chemicals of concern.’ The biological actions of these substances, alone or in combination with classical pollutants, can include effects such as endocrine disruption and neurotoxicity. Studies conducted by the Centers for Disease Control and Prevention as part of the National Health and Nutrition Examination Survey have shown that Americans are exposed to a large variety of chemicals, as shown through the analysis of whole blood, serum, and urine. The main source of these chemicals is not water, but rather food, house dust, cosmetics, personal care products, and air. However, not all of the drinking water is treated, and many chemicals are found at nanogram per liter levels. Urgent measures are needed to protect human health from contaminated drinking water supplies, which may be another avenue of exposure to unwanted chemicals. These measures include, but are not limited to, quantitative risk assessment, toxicological studies of xenobiotic mixtures including chronic effects, and the development of strategies to protect water resources. Furthermore, technological advances in water treatment and reliable water production will be a requirement to safeguard our water supply. In order to achieve these objectives, it is needed to understand what the emerging chemicals of concern are, as well as what analytical methods are required and what the cost implications are. Examples of chemicals of concern include pharmaceuticals, personal care products, alkylphenols and ethoxylates, perchlorate, nitrosamines, halogenated parabens, benzotriazoles, benzothiazoles, triclosan, perfluorinated compounds, flame retardants, steroids, geosmin, methylisoborneal, polar pesticides, and disinfection by-products. There are enormous numbers of analytical methods employed to analyze for emerging contaminants. The amount of time, resources, and expense required to analyze for all emerging contaminants in drinking water would be staggering. Even if this task was undertaken, it would be difficult to interpret the data, that is, clearly define chemicals that pose a risk to the population. A much more prudent approach is to apply the use of integrative sampling coupled with relevant short-term bioassays. An example is the yeast estrogen assay (or similar bioassay). The ability to separate complex mixtures is well developed. By applying short-term bioassays to isolate responsive elements, analytical efforts could be focused on identifying those elements. Clearly, multiresidue methods need to be applied in order to identify and quantify responsive elements. From this information, a toxicity balance can be determined, which would be useful to develop water treatment priorities. This chapter summarizes the current state of knowledge of emerging chemicals.