The U.S. EPA’s Contaminant Candidate List (CCL) serves as a lineup of the dubious chemical and microbial pollutants that likely pose a threat to drinking water, but have not yet been fully vetted by federal regulators.
The latest iteration of this roster, the CCL 4, was released late last year. For drinking water utilities and treatment plants, it can be seen as an indicator of regulations to come and a warning about what contaminants pose health concerns but are, for now, still permitted.
“The Safe Drinking Water Act (SDWA) directs the EPA to consider the health effects and occurrence information for unregulated contaminants as the agency makes decisions to place contaminants on the list,” said an EPA spokesperson. “SDWA further specifies that the agency place those contaminants on the list that present the greatest public health concern related to exposure from drinking water. EPA uses the CCL to identify priority contaminants for regulatory decision-making and information collecting.”
To select the 97 chemical and 12 microbial contaminants that constitute the CCL 4, the EPA started with the contaminants from its previous list that did not receive regulatory determinations. In the spring of 2012, it sought nominations from the public for any necessary additions. It then evaluated the available data for these contaminants in conjunction with any determinations made from previous CCLs and drafted the final CCL 4.
“The EPA uses this list of unregulated contaminants to prioritize research and data collection efforts to help the agency determine whether it should regulate a specific contaminant,” the spokesperson said. “Determining whether to regulate a CCL contaminant is completed in a separate process called ‘Regulatory Determinations’ that is also subject to public comment and review.”
Every five years the EPA must decide whether to regulate at least five contaminants on the CCL. Per the SDWA, it must determine the adverse effects of the contaminant on human health, the frequency and level of contaminant occurrence in public drinking water, and whether regulation of the contaminant is a meaningful opportunity to reduce public health risks.
As the first update to the CCL in five years, the CCL 4 lists several contaminants that have already made headlines and have been under the watch of local regulators, treatment plants, and environmental groups. For instance, 1,4-dioxane is listed, indicating that the EPA is concerned about it but has not yet made any decisions about the need for regulation. This can be frustrating to those who call for swifter action against pollutants that are known to cause health risks and can’t understand how this many concerning elements still await action.
“In general, the public has shown interest in the CCL, especially for contaminants of emerging concern,” the spokesperson said. “Drinking water utility organizations have expressed concern with the number of contaminants on the CCL.”
It will be some time before any of the contaminants listed on the CCL 4 receive regulatory limitations. To give a sense of how long the process takes, keep in mind that the final CCL 3 was released in 2009 and its regulatory determinations were completed in 2016. As an indicator of where things stand with each CCL 4 contaminant, Exhibit 2 of the list’s Federal Register Notice provides a summary of the available data that can be used to evaluate the contaminants.
“This table is presented to provide a sense of which contaminants are likely to have sufficient data for further evaluation under the next regulatory determination and those that have research needs,” said the spokesperson.
Those who are truly concerned about a given contaminant and want to urge the EPA toward action can conduct or advocate for studies that will provide the agency with the data it needs. While the CCL 4 does not impose any limitations on drinking water utilities, it would be in the best interest of safety advocates to at least become familiar with the contaminants it lists.
Image credit: "Bacterium" Christian Lundh © 2005 used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by-nd/2.0/