Key Finding: U.S. researchers detected a broad range of contaminants of emerging concern (CECs)—including pharmaceuticals, personal care products, and endocrine-disrupting compounds—in both source and treated drinking waters nationwide. While concentrations were generally low, their widespread presence underscores the critical importance of advanced water purification technologies such as reverse osmosis and activated carbon filtration.

Glassmeyer, S.T., et al., Science of The Total Environment, 581-582:909-922, March 2017

When chemical or microbial contaminants are assessed for potential effect or possible regulation in ambient and drinking waters, a critical first step is determining if the contaminants occur and if they are at concentrations that may cause human or ecological health concerns. To this end, source and treated drinking water samples from 29 drinking water treatment plants (DWTPs) were analyzed as part of a two-phase study to determine whether chemical and microbial constituents, many of which are considered contaminants of emerging concern, were detectable in the waters. Of the 84 chemicals monitored in the 9 Phase I DWTPs, 27 were detected at least once in the source water, and 21 were detected at least once in treated drinking water. In Phase II, which was a broader and more comprehensive assessment, 247 chemical and microbial analytes were measured in 25 DWTPs, with 148 detected at least once in the source water, and 121 detected at least once in the treated drinking water. The frequency of detection was often related to the analyte’s contaminant class, as pharmaceuticals and anthropogenic waste indicators tended to be infrequently detected and more easily removed during treatment, while per and polyfluoroalkyl substances and inorganic constituents were both more frequently detected and, overall, more resistant to treatment. The data collected as part of this project will be used to help inform evaluation of unregulated contaminants in surface water, groundwater, and drinking water.

Source: Water Feed

Understanding Contaminants of Emerging Concern in U.S. Drinking Water

Contaminants of emerging concern (CECs) represent a diverse category of chemical substances not traditionally monitored in environmental assessments but recognized as potential risks to human health and aquatic ecosystems. This landmark nationwide reconnaissance study sampled source waters and finished drinking waters from utilities across the United States, detecting hundreds of organic compounds including prescription and over-the-counter pharmaceuticals, hormones, flame retardants, pesticide metabolites, and industrial chemicals.

The study found that conventional drinking water treatment processes—coagulation, sedimentation, and chlorination—achieved only partial removal of many CECs. Compounds such as carbamazepine (an anticonvulsant), sulfamethoxazole (an antibiotic), and various estrogenic hormones were detected in treated finished water at low but measurable concentrations. This raises important questions about cumulative exposure and long-term effects, particularly for sensitive populations including infants, pregnant women, and immunocompromised individuals.

From a water treatment perspective, the findings reinforce the superiority of membrane-based technologies. Nanofiltration (NF) and reverse osmosis (RO) systems demonstrate rejection rates exceeding 95% for most CECs due to their ability to physically exclude molecules larger than 0.0001 microns. Advanced oxidation processes (AOPs), including UV/hydrogen peroxide and ozone/biological activated carbon (O3/BAC), also show strong efficacy against recalcitrant pharmaceuticals and endocrine disruptors.

Water utilities and industrial operators evaluating CEC risk should consider a multi-barrier treatment approach. Combining granular activated carbon (GAC) adsorption upstream with a high-rejection RO membrane provides a robust defense against the full spectrum of emerging contaminants identified in this study. Regular monitoring using liquid chromatography-tandem mass spectrometry (LC-MS/MS) allows operators to track CEC removal efficiency and adapt treatment protocols as new compounds are identified by regulatory agencies.