Contaminants of Emerging Concern Resource Page

Below is a list of resources and links, compiled by NEWEA’s CEC Committee, related to emerging and existing contaminants.

Additional scholarly articles are also available on the topics below. To access these additional articles, please fill out this form.

NEWEA has created the PFAS Task Force as a resource for PFAS communication and information sharing. Follow this link to NEWEA’s PFAS resource page.

Contact info

Chair: Amy Hunter

Request for Research/Articles: Camilla Kuo-Dahab

What are Contaminants of Emerging Concern? 

Contaminants of Emerging Concern (CECs) are chemicals that are newly discovered or known chemicals, where evolving information about their potential impacts to human health and/or the environment has prompted further evaluation and investigation. (Water Environment Federation, 2020). Follow this link to WEF’s position statement.

General Resources

Regional Regulatory Updates

Federal agencies and organizations



ITRC (Interstate Technology Regulatory Council)


The NEWEA CEC Committee has hosted seminars and webinars over the years highlighting Contaminants of Emerging Concern. Click the arrows below and follow the links provided to view CEC Conference and Seminar Proceedings in the Document Repository.








Outside New England State Resources

Conference Spotlight

Commonly Identified CECs


Plastic particles smaller than 5 millimeters across. Sources include industrial abrasives, microbeads in personal care products (phased out in the US in 2015), resin pellets spilled into the environment (nurdles), and breakdown of larger plastic debris over time. A majority of the plastic particles found in the environment consists of a few common polymer types: polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polyvinyl chloride, and others. 


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Material less than 100 nanometers and can derive from a variety of products such as carbon (e.g. combustion reactions) or minerals (e.g. silver). They can be naturally occurring or engineered materials to serve functions for pharmaceuticals and healthcare, electronics, personal care products, and textiles.  


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Endocrine Disrupting Compounds (EDCs): 

EDCs are chemicals that can interfere with the hormonal systems of humans and wildlife, causing disruptions in growth, development, reproduction, and immune function. EDCs can be found in various sources, such as pesticides, plastics, industrial chemicals, and pharmaceuticals. Some examples of EDCs include bisphenol A (BPA), phthalates, polychlorinated biphenyls (PCBs), and certain pesticides. The growing concern around EDCs is due to their potential to accumulate in the environment and bioaccumulate in organisms, as well as their capacity to cause harmful effects even at low concentrations.


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Per- and Polyfluoroalkyl Substances (PFAS/GenX Chemicals): 

Per- and Polyfluoroalkyl Substances (PFAS) are class of synthetic compounds (numbering in the thousands) that are based on carbon ‘backbones’ of various length that are bonded to fluorine ions; perfluoroalkyl compounds’ carbon chains are fully populated by fluorine ions. These carbon-fluorine bonds are very strong, making many PFA substances resistant to degradation and therefore persistent when released to the environment.  Being known for their hydrophobic and lipophobic properties as well as effectiveness in fire suppression, these chemicals have found widespread use for things such as food packaging, stain and water resistant fabric, makeup, and fire fighting foam.  Because persistence and toxicity are related to the carbon chain length, significant research is needed to more fully understand the health and environmental risks associated with this class of compounds.  Research on two of the more widely used long-chain chemicals, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), has demonstrated a correlation with PFAS concentration and kidney and testicular cancers, thyroid disease, pregnancy-induced hypertension/pre-eclampsia, low birth weight, high cholesterol, liver disease, and reduction in vaccine efficacy.

GenX refers to a group of PFAS that are used as replacements for older PFAS compounds, such as PFOA and PFOS. GenX chemicals are used in various industrial processes and consumer products, such as non-stick coatings, stain-resistant fabrics, and firefighting foams. Like other PFAS, GenX chemicals are persistent in the environment, can accumulate in living organisms, and have been associated with potential adverse health effects in humans, such as liver damage, immune system dysfunction, and developmental issues. Research is ongoing to better understand the environmental fate and potential risks of GenX chemicals.


Other Researchers:

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1,4 dioxane: 

1,4-dioxane is a synthetic industrial chemical used primarily as a solvent and stabilizer in the manufacture of other chemicals, such as in the production of polyethylene terephthalate (PET) plastic and some detergents. It is also a byproduct of certain processes, such as the ethoxylation of surfactants. 1,4-dioxane is considered a contaminant of emerging concern because it is highly persistent in the environment, can migrate through soil and groundwater, and has been classified as a probable human carcinogen by the U.S. Environmental Protection Agency (EPA).


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Pharmaceuticals & Personal Care Products (PPCPs):

A diverse group of chemicals including, but not limited to, prescription and over-the-counter human drugs, veterinary drugs, diagnostic agents, nutritional supplements, and other consumer products such as fragrances, cosmetics, insect repellants, sun-screens, and detergents. PPCPs can be introduced into the environment through several different modes. Products, like sunscreen, can rinse off directly into water bodies during swimming activities. PPCPs can enter wastewater through rinsing, consumption and excretion, as well as direct disposal. Wastewater is either disposed of through septic system that discharge to groundwater, or water resource recovery facilities (WRRFs) that discharge to surface water bodies. Septic systems and WRRFs were not designed to fully treat the compounds present in PPCPs. These compounds can be toxic to aquatic life and/or bioaccumulate in the food chain, similar to mercury.


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Bisphenol A (BPA): 

Bisphenol A (BPA) is an industrial chemical that has been widely used since the 1960s in the production of polycarbonate plastics and epoxy resins. Polycarbonate plastics are used in a variety of consumer goods, such as water bottles, food containers, and sports equipment, due to their durability, impact resistance, and transparency. Epoxy resins containing BPA are used as protective coatings and linings for food and beverage cans, as well as in various industrial applications like adhesives and paints.

BPA is a concern because it can leach from plastic products and food can linings into food and beverages, leading to potential human exposure. BPA is classified as an endocrine-disrupting compound (EDC) because it can interfere with the normal functioning of hormones in the body, particularly estrogen. Exposure to BPA has been associated with various adverse health effects, including reproductive and developmental issues, neurobehavioral problems, and an increased risk of certain cancers.

Due to the growing concerns about the potential health effects of BPA exposure, regulatory agencies in various countries have implemented restrictions or bans on the use of BPA in certain products, particularly those intended for infants and young children. This has also led to the development of BPA-free alternatives for polycarbonate plastics and epoxy resins.

Additionally, research is ongoing to better understand the potential health risks associated with BPA exposure, as well as to develop methods for detecting and removing BPA from the environment and contaminated products.


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Disinfection Byproducts (DBPs):  

Disinfection by products(DBPs) are unintentionally formed in the water distribution system when disinfectants like chlorine or chloramine react with natural organic matter.Chronic exposure of DBPs at elevated levels could have carcinogenic effects. DBPs could be carbonaceous or nitrogenous in nature. The nitrogenous DBPs are more cytotoxic and genotoxic than their carbonaceous counterparts. Trihalomethanes (THMs) and Haloacetic acids(HAAs) are the most common classes of DBPs.The different routes of exposure of DBPs include ingestion, dermal contact during swimming or showering.


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N-nitrosamine (NDMA): 

N-nitrosamines are a group of organic compounds that can form from the reaction of nitrogen-containing compounds with nitrosating agents. N-nitrosodimethylamine (NDMA) is a specific type of N-nitrosamine that has gained attention as an emerging contaminant due to its potential to cause adverse health effects and its presence in the environment.

NDMA is classified as a probable human carcinogen by the U.S. Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC). It has been associated with an increased risk of developing cancer, particularly in the liver and gastrointestinal tract. NDMA can be found in various sources, including industrial processes, food, tobacco smoke, and certain consumer products.

NDMA can also form as a byproduct during water disinfection processes, such as chlorination and ozonation, when disinfectants react with nitrogen-containing organic compounds, like those found in pharmaceuticals, personal care products, and natural organic matter. As a result, NDMA can be detected in drinking water, wastewater, and surface water.

The presence of NDMA and other N-nitrosamines in water supplies has raised concerns about the potential risks to human health, leading to efforts to better understand their sources, occurrence, and fate in the environment. Additionally, research is being conducted to develop effective methods for their removal from water, including techniques like adsorption, advanced oxidation processes, and biological treatment. Regulatory agencies are also working on establishing guidelines and limits for NDMA and other N-nitrosamines in drinking water to protect public health.


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Neonicotinoids are a class of synthetic insecticides that are chemically similar to nicotine. They are widely used in agriculture and horticulture to protect crops from pests, such as aphids, whiteflies, and beetles. Neonicotinoids act on the nervous systems of insects by binding to nicotinic acetylcholine receptors, causing paralysis and death.Neonicotinoids have become emerging contaminants due to growing concerns about their potential negative impacts on non-target organisms and the environment. Some of the concerns associated with neonicotinoids include:

  • Effects on pollinators: Neonicotinoids have been implicated in the decline of bee populations, as they can have sublethal effects on bees, impairing their foraging, navigation, and reproduction abilities. This has led to restrictions and bans on the use of certain neonicotinoids in some countries.
  • Aquatic toxicity: Neonicotinoids are highly water-soluble, which means they can leach into groundwater and surface waters, potentially affecting aquatic organisms. Studies have shown that neonicotinoids can have adverse effects on various aquatic species, including insects, crustaceans, and fish, at environmentally relevant concentrations.
  • Persistence in the environment: Some neonicotinoids can persist in soil and water for extended periods, increasing the potential for long-term exposure and accumulation in the environment.
  • Development of resistance: Pests may develop resistance to neonicotinoids, reducing the effectiveness of these insecticides and leading to the need for alternative pest management strategies.


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Cyanotoxins are toxic compounds produced by cyanobacteria, also known as blue-green algae. They can be found in surface waters, such as lakes and reservoirs, particularly under conditions that promote algal blooms, like warm temperatures and high nutrient levels. Some common types of cyanotoxins include microcystins, cylindrospermopsin, and anatoxin-a. Exposure to cyanotoxins can cause various health effects in humans and animals, ranging from skin irritation and gastrointestinal symptoms to liver damage and neurotoxicity. As an emerging contaminant, there is growing concern about the presence of cyanotoxins in drinking water sources, recreational waters, and aquatic ecosystems.


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Triclosan is an antimicrobial agent that has been widely used in personal care products, such as hand soaps, toothpaste, and deodorants, as well as in various consumer goods like cutting boards and textiles. Triclosan has been identified as an emerging contaminant due to its potential to cause ecological and human health impacts. It can persist in the environment, bioaccumulate in organisms, and has been associated with endocrine-disrupting effects. Additionally, there are concerns that the widespread use of triclosan may contribute to antibiotic resistance.


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Antibiotic resistance:

Antibiotic resistance refers to the ability of bacteria to develop resistance to antibiotics, which are drugs used to treat bacterial infections. The emergence of antibiotic-resistant bacteria is a growing public health concern and has been linked to the overuse and misuse of antibiotics in human medicine and agriculture. Antibiotic-resistant bacteria can enter the environment through wastewater, animal waste, and runoff from agricultural fields, potentially spreading resistance genes to other bacteria and posing risks to human and animal health. Efforts to address antibiotic resistance include promoting the responsible use of antibiotics, developing new treatments, and implementing strategies to prevent the spread of resistant bacteria in the environment.


Management Options for Reducing the Release of Antibiotics and Antibiotic Resistance Genes to the Environment | Environmental Health Perspectives | Vol. 121, No. 8 (

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Drinking water is treated with a final disinfection step that typically entails adding chlorine-based compounds.  Trace organic and naturally occurring substances like humic acids that remain after prior treatment can slowly react with the added disinfectant within the distribution system as well as sun-warmed water towers to yield “disinfection by products” such as trihalogenated methanes (THMs). THMs are acknowledged to be carcinogenic.  Bromides naturally present in the source water or introduced from natural gas extraction waste streams can also participate in the chemistry thereby increasing the range of compounds formed.  THM concentrations are regularly measured throughout a distribution system and a system is in violation when a regulatory standard is exceeded thereby triggering more extensive monitoring and the development of a remediation plan.  The EPA-set maximum contaminant level for THMs is 80 parts per billion, a standard also used in some Canadian provinces such as Quebec.


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