"What we find in the environment often depends on what we look for and how hard we look."
This statement, which had appeared on the USGS (US Geological Survey) website, most accurately describes the concept of emerging contaminants. Also known as contaminants of emerging concern (CECs), the use of the CEC abbreviation is becoming more prevalent in the associated literature and environmental news coverage. The USGS statement addresses the two major associated environmental monitoring concerns. The first is that the list of routinely monitored environmental contaminants is far shorter than the list of potential contaminants that could be released into the environment. The second, is that often, environmental monitoring is not conducted at the degree of sensitivity that is required in order to register contaminants, if detected.
The United States Environmental Protection Agency (EPA) enacted the Unregulated Contaminant Monitoring Rule (UCMR) as part of the Safe Drinking Water Act (SDWA) amendments in 1996. The UCMR serves as an overall drinking water monitoring program that catalogs the occurrence and concentration of selected CECs in the nation's drinking water supply and provides valuable information about the frequency of these impurities. The UCMR was designed to collect data for contaminants that are suspected in drinking water and do not have health-based standards set under the SDWA or are otherwise not regulated. Monitoring for up to 30 different contaminants on a five-year cycle, the UCMR also focuses on tracking large public water supplies, but it also monitors a representative number of smaller public water systems as well. The EPA has a formal review process in place to review and evaluate potential UCMR monitoring candidates and prioritizes its work based on current research on occurrence and health effect risk factors, among other rationale. Four rounds of UCMR monitoring have been conducted, with a fifth being planned. Perchlorate, 1,4-dioxane and PFAS compounds are some of the most well known emerging contaminants that have been included in UCMR monitoring rounds.
The reason emerging contaminants are spiking a heightened level of awareness and concern among environmental professionals, is that there is limited information available about the risks to human health and the environment associated with the release of these toxins. Formal studies into the potential human health effects due to exposure to a specific chemical are sparse. Emerging contaminants are increasingly being detected at low levels in surface water, and there is concern that these compounds may have an impact on aquatic life. Many emerging contaminants can potentially act as endocrine disruptors, which are compounds that can alter the normal functions of hormones resulting in a variety of health effects. These compounds may also demonstrate low acute toxicity but cause significant reproductive effects at very low levels of exposure.
Much more needs to be learned as to the fate and transport characteristics of emerging contaminate compounds in the environment, as well as the most beneficial remediation technologies that can be employed for treatment and site remediation. In addition, from the laboratory perspective, the availability of standardized analytical procedures for many potential emerging contaminants often lags far behind the desire to look for them in air, water, soil, and tissue samples. The current lack of standardized methods for PFAS (per- and polyfluoroalkyl substances) analysis in various environmental media is a case in point and illustrative of the larger emerging contaminants issue.
As mentioned previously in conjunction with the UCMR discussion, perchlorate, 1,4-dioxane and PFAS, are some of the most readily identifiable and most well-known examples of emerging contaminants. Perchlorate was included in the first UCMR monitoring round (UCMR 1) and it is a good example about what is meant as an emerging contaminate. Also included in UCMR 1 was methyl tertiary butyl ether (MTBE), which was used as a gasoline additive and other industrial applications. MTBE was strongly suspected to be well represented when the UCMR1 data was evaluated, but little was known as to the prevalence of perchlorate in water supplies. The overall high frequency of perchlorate detections in UCMR 1 was a surprise.
1,4-Dioxane was included in UCMR 4 and its frequency of detection in the monitored water supplies was also greater than anticipated. Unlike perchlorate, a parameter that was rarely included in past surveys of drinking water and non-potable water alike, 1,4-dioxane had been included on volatile organic compounds (VOC) target compound lists for at least a decade prior to UCMR 4. Anecdotally, there was not a lot of prior 1,4-dioxane analytical data that would have indicated that 1,4-dioxane could be present in water supplies to the extent seen in UCMR 4. The reason for that has to do with the chemical properties of 1,4-dioxane, past analytical methods and more recent toxicological data that indicated 1,4-dioxane could represent more of a risk at lower concentrations, requiring more sensitive analytical procedures. The analytical method used in UCMR 4 for 1,4-dioxane was specific to this compound and it was an ultra- sensitive method that could report low detection limits. The recognition of PFAS as an emerging contaminant is similar to perchlorate’s emergence. This is because PFAS were not routinely analyzed prior to UCMR 4 and their examination required analytical instrumentation not commonly available in environmental laboratories at the time.
Alpha Analytical has been supporting emerging contaminants monitoring programs for nearly 20 years, beginning with the IC/MS/MS analysis of perchlorate in 2004. We later developed an isotopic dilution procedure for the low-level analysis of 1,4-dioxane and we have gained considerable experience with the LC/MS/MS analysis of PFAS. We currently offer perchlorate analysis by Methods 332 and 6860; 1,4-dioxane analysis by Methods 8260, 522 and 8270 SIM and PFAS analysis by Methods 533, 537.1 and a modified isotopic dilution procedure. For more information on any of these analyses, please click on the above links.
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