New and emerging drinking water contaminants continue to be a hot-button issue for the water treatment industry. With much of the focus in the last year on Per- and Polyfluoroalkyl substances (PFAS), many may be wondering what the next major contaminant will be to come down the pipeline.
But before we jump into the developing field of emerging contaminants and other notable drinking water pollutants like PFAS, Chromium-6, and microplastics, let’s discuss the regulatory process. The way the U.S. Environmental Protection Agency (EPA) and policymakers across the county encourage scientific research, regulate and restrict drinking water contaminants emphasizes the importance of point-of-use (POU) and point-of-entry (POE) technologies in supporting health and safety.
Regulatory Determinations for Drinking Water
By using a science-based approach to regulate drinking water, the EPA has subsequently encouraged public and private sector understanding of health-based contaminants. Through the investment into research for testing and treatment capacity-building requirements necessary to understand these emerging contaminants.
The Safe Drinking Water Act (SDWA) has allowed the EPA to protect the health and safety of the nation’s public drinking water supply since 1974. When analyzing risks, the EPA must abide by a multi-step framework for developing new regulations over a five-year cycle and revising existing regulations. And these regulatory determinations by the EPA aren’t always considered an absolute decision to regulate; this process involves a comprehensive review of toxicological and occurrence data, the overall impact on human health, and weighing the feasibility of treatment or mitigation.
The Contaminant Candidate List (CCL) is the first stop in the EPA’s assessment of contaminants that present a risk to drinking water sources. The EPA recently finalized the next iteration of this list, the CCL 5, which includes 66 different chemicals and three chemical groups PFAS, cyanotoxins and disinfection byproducts (DBPs), and 12 microbes. However, when minimal data is available from the CCL, the EPA often requires a handful of these substances to be monitored by water systems through the Unregulated Contaminant Monitoring Rule (UCMR). These two steps help guide researching, testing and monitoring, all of which are vital in understanding the impacts of emerging contaminants and methods to treat them through POU and POE technologies.
The final stage of regulating drinking water is often dependent on a variety of factors. The EPA evaluates the trade-offs associated with human health impacts, occurrence and frequency data, and the feasibility of treatment options. These factors influence the policy mechanism the EPA uses. For example, health advisories, Maximum Contaminant Level Goals (MCLGs), and guidance are all tools that are non-enforceable. However, the EPA can also issue National Primary Drinking Water Regulations, such as a Maximum Contaminant Level (MCL) and or an Action Level (AL) are legally enforceable by the agency. All these actions by the EPA are open for public comment and this engagement with stakeholders allows for the dissemination of information to guide science-based policy related to drinking water.
Emerging Contaminants & Treatment
This multi-step approach to research, regulate and restrict emerging contaminants have influenced testing procedures across the United States, presenting opportunities to identify and understand emerging drinking water contaminants. As mentioned, some examples of emerging contaminants include PFAS, Chromium-6, and microplastics. Many of these compounds are found in pharmaceuticals and personal care products and are used in industrial processes and agriculture. Additionally, the review of new scientific findings for emerging contaminants and the regulatory process associated with drinking water here in the United States exhibits the influence of policy on the water treatment industry.
Chromium-6
For instance, chromium is a naturally occurring element that can be found in various forms, such as chromium-3 (trivalent chromium) and chromium-6 (hexavalent chromium). Chromium-3 is an essential nutrient and is not considered harmful to human health, while chromium-6 is a toxic form of the element that can cause cancer. Understanding the health implications between these two substances is driving the EPA to review the Agency’s total Chromium MCL of 100 parts per billion (ppb). The EPA Science Advisory Board (SAB) is examining the IRIS Toxicological Review of Hexavalent Chromium to provide scientific support and develop a rationale for a national standard for this contaminant in drinking water. However, a lack of federal standards for specifically chromium-6 in drinking water has not stopped some states, such as California, from setting their own limits. In March 2022, California proposed an MCL of 10 ppb for chromium-6, a value that is 10 times below the EPA MCL for total chromium.
The process that is currently underway for chromium-6 is very similar to the approach the EPA has used to research, regulate and restrict PFAS. But in areas where there is minimal understanding from both a scientific perspective and hard data (i.e., occurrence and frequency data), science policy and the EPA’s regulatory process will continue to drive the investment into research and the capacity building necessary to test and treat emerging contaminants.
Microplastics
Microplastics is an evolving field, and with no federal regulations, states have begun exploring potentially harmful contaminants. In California, a law passed in 2018 (and codified in Health and Safety Code § 116376) will require testing for microplastics in public water systems starting in the Fall of 2023. Some studies have found microplastics in tap water, bottled water, and even in some treated drinking water. The effects of consuming microplastics in drinking water are not well understood, but research is ongoing to determine any potential risks to human health.
Treatment
When it comes to mitigating new and emerging drinking water contaminants, POU and POE technologies can be vital in providing a final barrier. For chromium-6 and some PFAS, granular activated carbon (GAC) and reverse osmosis (RO) water treatment systems can be effective at removing them from drinking water. Ion exchange can also be used for removing chromium-6 but it is less common.
The important item to note is that third-party certification to voluntary consensus-based standards developed by the National Sanitation Foundation (NSF) and the American National Standards Institute (ANSI) can help ensure drinking water treatment systems are effective at removing these contaminants. Currently, NSF/ANSI 58 for RO systems and NSF/ANSI 53 for GAC are common standards used to mitigate the presence of these contaminants. POU and POE devices can also be certified for the claim of removing microplastics under NSF/ANSI 401, but the test protocol is NSF/ANSI 42 for particulate class I reduction. Visit the Water Quality Association website for more information on certified products.
Science-based policy has influenced innovation in the drinking water treatment industry through the regulatory process and will continue to drive investment into research, testing, and treatment. These policies exhibit the importance of POU, POE, and other final barrier technologies that will evolve and guide policymakers’ ability to regulate new and emerging contaminants.
