Compounds of Emerging Concern

CECs: What Are They & Should I Be Worried?

Compounds of emerging concern — or CECs — have gained notoriety in recent years. CECs include pharmaceuticals, personal care products, endocrine disrupters, and antibiotic resistance genes that can turn up in water supplies. They are unregulated by federal and state water quality agencies because they occur at extremely low concentrations — nanograms per liter. In fact, laboratory equipment could not detect these compounds until about 2002. Improvements in analytical technology now allow labs to detect compounds below the concentrations that are known to impact public health. 

More specifically, CECs are synthetic chemicals that are presently unregulated but for which there is scientific concern that they may be hazardous to the health of people, other species, or the environment. They are not presently regulated because there is insufficient testing or knowledge to set science-based safe limits or there has been a decision not to regulate. They include selected pharmaceuticals, personal care products, herbicides, pesticides, industrial cleaning agents, and fire retardants. When found in public water supplies, they often occur in extremely low concentrations - nanograms per liter, or, parts per trillion (ppt). Despite low concentrations, some of these chemicals are known or suspected to pose risks to human health and aquatic organisms.

The City of Flagstaff “recycles” over 700 million gallons of water each year, a process that entails treating wastewater from our homes and businesses to meet state and federal water quality standards. This treated water — also known as reclaimed water, recycled water, or effluent — is delivered via a separate distribution system. Reclaimed water is used by communities around the world for irrigation, and the City has used this proactive water conservation strategy since 1965, at the “Bill Johnston Golf Properties” (now Continental Country Club). 

Tackling a Tough Issue: Flagstaff’s CEC Advisory Panel (2013-2018)

Recognizing the importance of this issue, Kevin Burke, Flagstaff’s previous City Manager, organized an advisory panel of 12 local, state, and nationally recognized researchers, scientists, and industry professionals to help understand what CECs mean to Flagstaff. The Advisory Panel first met in January 2013 to identify steps to better understand the effects, if any, of CECs in our raw, treated, and reclaimed water. Discussions initially focused on “human health impacts” rather than animal, aquatic, or environmental impacts.

Results of Interim Report 

The Panel issued an Interim Report in July 2013, which contained numerous findings, recommendations, and priorities on CECs in drinking water and reclaimed water - including a finding that CECs pose no risk to either drinking or reclaimed supplies in Flagstaff. A few of these findings and recommendations are summarized below.

Drinking Water

The EPA, based on analyses and the advice of national scientific panels, has developed a list of currently unregulated CECs that may warrant further consideration for regulation in drinking water. This “Contaminant Candidate List #3” (CCL3) focuses on human health impacts and does not yet include antibiotic resistance genes or microbes. The Advisory Panel recommended that the City consider evaluating which contaminants on the list are used or prescribed within the Flagstaff community as background information in preparation for potential future regulation. You can also see "Reclaimed Water: Is It Safe?" for more information

Reclaimed Water

The Advisory Panel found that there are currently no data to suggest that the continued use of reclaimed water provides an undue risk to human health; however, it recommended that the City monitor for four chemicals on the CCL3 list. A subgroup was tasked with outlining a cutting-edge epidemiological and microbial study and searching for funding with partners or agencies; such a study would provide a better understanding of what it means if we detect antibiotic resistance genes or bacteria in Flagstaff’s reclaimed water. The Advisory Panel suggested a parallel study to compare the effects of various water treatment technologies on the removal of CECs, specifically antibiotic-resistant genes in reclaimed water.

CEC Panel Findings

The Advisory Panel met again in July 2016, building upon earlier studies. The final report was published in January 2018, with a determination that Flagstaff's water system currently meets all U.S.EPA and state regulatory requirements.  

View the final report here:
January 2018 Final Report Update (PDF)



The Water Research Foundation (WRF) has published several informational pieces on CECs including fact sheets on pharmaceuticals and personal care products in water supplies by Dr. Shane Snyder, a member of our Advisory Panel. 

For more information, contact Erin Young, R.G., Water Resources Manager at 213-2405 or email Erin Young.