Emerging Contaminants

MassDEP works with stakeholders on addressing emerging contaminants, on proactive state initiatives aimed at identifying new potential public health and environmental problems, and on processes for deciding if / how MassDEP should address them. 

In 2006, Massachusetts became the first state in the nation to promulgate drinking water and waste site cleanup standards for perchlorate, a contaminant that was previously unregulated by any state or the federal government. MassDEP engaged stakeholders in this groundbreaking effort to gather and exchange information on perchlorate sources, occurrence, health risks, analytical monitoring methods and treatment techniques. Based on this information, MassDEP established a drinking water standard of two (2) parts per billion (ppb) for this emerging contaminant in 2006. The following year, MassDEP continued to consult with stakeholders about addressing other emerging contaminants, which led to the establishment of an Emerging Contaminant Workgroup. These proactive state initiatives are aimed at identifying new potential public health and environmental problems, and providing a process for deciding if and how MassDEP can or should address them. 

Table of Contents


MassDEP considers 1,4-dioxane an emerging contaminant because it is toxic, widely used so that pathways for human exposure exist, and health protection standards are needed. 1,4-dioxane is a synthetic chemical with many uses as a solvent. It is used as a stabilizer for chlorinated solvents used in degreasing operations and is present in many products (e.g., paint, varnish remover, antifreeze, airplane deicing solutions and an impurity in many personal care products, etc). Based on toxicity studies, EPA has categorized 1,4-dioxane as likely to be carcinogenic to humans. It is also to undergo Tier 1 screening as an endocrine disruptor under the EPA Endocrine Disruptor Screening Program. In addition, growing evidence exists that 1,4-dioxane may be more prevalent in groundwater throughout the United States than previously realized, potentially due to releases from hazardous waste sites and landfills. Enhanced monitoring efforts for 1,4-dioxane are underway. For example, the EPA has listed 1,4-dioxane under the Unregulated Contaminant Monitoring Rule 3 (UCMR3) in order to collect information on the frequency and levels of 1,4-dioxane in public drinking water supplies across the United States, including those in Massachusetts. Based on these findings and other determinants, EPA will determine if a national drinking water standard, or Maximum Contaminant Level (MCL), for 1,4-dioxane should be set to protect public health.

MassDEP Workplan:  

  • MassDEP recently set groundwater and soil cleanup standards for 1,4-dioxane in its hazardous waste site cleanup program (M.G.L. Chapter 21E). These were promulgated in April 2014. See: 310 CMR 40.0000 - Massachusetts Contingency Plan (MCP).
  • The agency will include 1,4-dioxane in upcoming revisions to its Laboratory Certification regulations.
  • MassDEP also has updated its drinking water guideline for 1,4-dioxane. See: Current Regulatory Limit: 1,4-Dioxane
  • The agency will obtain data about the presence of 1,4-dioxane in Massachusetts public water supplies due to EPA’s Unregulated Contaminant Monitoring Rule 3 (UCMR3) for nationwide testing of public drinking water supplies (2013 to 2015). MassDEP will respond to any cases in which standards and guidelines for 1,4-dioxane are exceeded.

Additional Resources

Cyanobacteria (Blue Green Algae)

Also newly identified as an emerging contaminant in July 2013, these bacteria produce toxins which accumulate in water, and in high concentrations can even kill animals and people.

Cyanobacteria are microscopic bacteria that live in all types of waterbodies. A large growth of these bacteria results in algal blooms. These blooms can pollute the water and may even be toxic to animals and people.

Cyanobacterial Harmful Algal Blooms (CyanoHABs) & Water


Nanoparticles are an ongoing emerging contaminant issue for several reasons.  Nanotechnology is a rapidly evolving technology where a wide variety of engineered nanoparticles, which lack health and safety information, are being introduced into a wide array of products or uses which have the potential to lead to human exposures.

Nano refers to a billionth and nanoparticles are generally in the range of a billionth of a meter, or 1 to 100 nanometers. To put this in perspective, the average human hair is about 25,000 nanometers wide and the head of a pin is 20 million nanometers wide. Nanoparticles come in many forms and due to their small size and large surface area, they hold special and unique properties. Nanotechnology is the science of manipulating tiny particles in the nanometer range.  

Nanotechnology is an ‘enabling’ technology, where nanoparticles are engineered to perform specific functions. Nanotechnology has been applied in the fields of energy, medicine, environment, electronics, consumer products, transportation and agriculture. The emergence of nanotechnology has been compared with the industrial revolution and is likely to have a significant impact on almost all areas of society as it may replace much of our manufacturing base with new processes and products.

Nanotechnology holds great promise for the future and can provide many benefits to society. In 2007, MassDEP determined that nanoparticles met its definition of an emerging contaminant. The agency’s initial step was to establish a Massachusetts Interagency Nanotechnology Committee with a key effort being to promote the safe development of nanotechnology in Massachusetts.

Additional Resources


Perchlorate is considered an ongoing emerging contaminant because toxicity information is being updated and re-evaluated; more information has been developed on sources and pathways of human exposure, and the U.S. Environmental Protection Agency (EPA) is working to set standards for perchlorate in drinking water under the Safe Drinking Water Act.

In 2007, Massachusetts was the first state in the country to set drinking water and hazardous waste site cleanup standards for perchlorate. Perchlorate is used in rocket fuel, munitions, fireworks, flares, some blasting agents and can be a contaminant in certain drinking water disinfection products. It is an endocrine disrupter and affects thyroid hormone levels responsible for normal growth and development. In 2011, EPA announced plans for setting an Maximum Contaminant Level (MCL) for perchlorate, reversing a 2009 decision not to regulate perchlorate in drinking water. Since MassDEP set its standards, new information has emerged on perchlorate’s toxicity, sources of exposure and body burdens in the U.S. population. EPA has also developed updated methodologies for assessing the toxicity of chemicals and for deriving toxicity values used to set health protection standards.

MassDEP Workplan:

It is important for MassDEP to review and evaluate EPA’s work, and to comment on proposed federal rulemaking. Specifically, the agency will:

  • Review and comment on EPA’s proposed Maximum Contaminant Level Goal (MCLG, a health-based level) when it is published in the Federal Register.
  • Also review and comment on EPA’s proposed MCL (a level that considers health risk, cost and feasibility).
  • Consider adopting EPA’s MCL for Massachusetts or maintaining its current state MCL, which is allowed if it is more protective than the EPA standard. Any modifications to the existing Massachusetts perchlorate toxicity value and standards will require consultation with the MassDEP Bureau of Waste Site Cleanup.

Additional Resources

Per- and Polyfluoroalkyl Substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) are a family of chemicals used since the 1950s to manufacture stain-resistant, water-resistant, and non-stick consumer and industrial products.  Certain types of firefighting foam - historically used by the U.S. military, local fire departments, and airports to fight oil and gasoline fires - may also contain PFAS.

Many PFAS compounds do not breakdown in the environment. They are also water soluble and, depending on the dose, may cause a range of adverse health effects. Several of the PFAS known to be most problematic have been phased-out of use in the US and Europe. However, because they do not breakdown readily, past uses and releases of even the phased-out PFAS have contaminated groundwater and drinking water in some areas across the US and in MA.  

The extent of PFAS contamination and their potential health risks is an area of rapidly-evolving science, and a growing issue of concern to MA and many other states. Additional information on PFAS and efforts by MA, Federal agencies, and other states to address these emerging contaminants can be found under Additional Resources below:

Additional Resources

Pharmaceuticals, Personal Care Products & Endocrine Blocking Compounds

Although cosmetics and drugs have been used and prescribed for centuries, advances in scientific detection have only recently raised concerns about the presence of these chemicals in the environment.

Find a kiosk or one-day event near you to dispose of prescription drugs that are expired or no longer needed: Safely Dispose of Prescription Drugs

Polybrominated Diphenyl Ethers (PBDEs)

MassDEP considers polybrominated diphenyl ethers (PBDEs) as ongoing emerging contaminants due to new scientific information indicating that exposures to them are widespread, no standards for PBDEs have been set, and human health effects information is evolving.

PBDEs are a class of halogenated flame retardants that are commonly used in a wide array of consumer goods. Examples include furniture foam padding, wire insulation, rugs, draperies, upholstery and plastic cabinets for personal computers, televisions, and small appliances. Because PBDEs do not bind chemically to polymers in textiles or plastics, they can leach out and be washed down sink and shower drains or become part of household or office dust, where they can be present in high concentrations. Also, PBDEs can be introduced into water and air during manufacture or disposal of household appliances. They are bioaccumulative (build up in the environment over time) and lipophilic (stored in fat). In animal studies, these chemicals have shown some effects on the thyroid and liver, as well as on brain development. More research is needed to assess the human health effects of exposure to PBDEs.

MassDEP Workplan:

  • Follow the U.S. Environmental Protection Agency (EPA) Action Plan.
  • Determine any potential future actions by MassDEP.


Additional Resources

RDX or Royal Demolition Explosive (Cyclotrimethylenetrinitramine)

This nitroamine compound was widely used by the military during World War II. MassDEP has established cleanup standards in 310 CMR 40.0000: The Massachusetts Contingency Plan (MCP).

Tetrachloroethylene (PCE)

For many years, MassDEP has derived and updated cancer risk values for PCE due to the absence of formal toxicological guidance from the U.S. Environmental Protection Agency (EPA). What has currently made PCE an emerging contaminant is EPA’s recent cancer risk assessment for PCE which differs to greatly from MassDEP’s interpretation of the literature.

Tetrachloroethylene is a synthetic chemical that is widely used for dry cleaning of fabrics and for metal-degreasing operations. It is also used as a starting material for making other chemicals and is used in some consumer products. Another name for tetrachloroethylene is perchloroethylene (PCE or PERC).

In February 2012, EPA published its first cancer toxicity values (or unit risk ) for tetrachloroethylene (PCE) on the Integrated Risk Information System (IRIS). Using well established methods, EPA calculated two values based on cancers observed in animals treated with PCE under controlled experimental conditions. One value was based on liver tumors and the second on a type of leukemia. The liver tumor-based value results in a human cancer risk value that is about 33 times lower (less risky) than the leukemia-based value. EPA selected to adopt the cancer toxicity value based on liver tumors. While the majority of the National Research Council (NRC) recommended use of the liver tumor data, council members did not reach a full consensus on this matter.  

MassDEP considers PCE an emerging contaminant due to the new cancer risk information and a lack of consensus about which tumor type should be used to protect public health. It is also a common contaminant at hazardous waste sites found in groundwater and indoor air of buildings via vapor intrusion. In addition, the new EPA value is much less stringent (less protective) than the current MassDEP value. As a result, MassDEP conducted an in-depth assessment on this issue.

MassDEP Workplan:

  • Update the MassDEP Cancer Risk Value for deriving health based standards. Take into account the EPA 2012 new toxicity values published in the Integrated Risk Information System (IRIS). MassDEP will initially propose toxicity values and cleanup standards which will be published for review and comments. Submitted comments will be considered as part of MassDEP’s work to promulgate cleanup standards for groundwater and soil.  
  • Update existing tetrachloroethylene standards based on the outcome of this work. These include waste site cleanup standards and Allowable Ambient Air Limits.   


Additional Resources

Trichloroethylene (TCE)

MassDEP considers TCE as an emerging contaminant due to evolving scientific information indicating that exposure to TCE may result in fetal heart defects (U.S. Environmental Protection Agency (EPA), 2011). In addition, TCE is a common contaminant at hazardous waste sites where people may be exposed to TCE in indoor air as a result of groundwater/vapor intrusion into residences and workplaces.

TCE is a synthetic, volatile organic chemical. It is used mainly as a solvent to remove grease from metal parts, but it is also an ingredient in adhesives, paint removers, varnishes, typewriter correction fluids, and spot removers. It is also used in the manufacture of other chemicals. TCE can be found in consumer products such as metal degreasing solvents for use on cars, bikes, or as an ingredient in hobbyist products. TCE is mainly emitted into the ambient air from metal degreasing operations. Wastewater from metal finishing, paint and ink formulation, electrical/electronic components, and rubber processing industries also may contain trichloroethylene.  Due to widespread use of TCE and its volatility, TCE has been detected in air, water and is a common environmental contaminant at hazardous waste sites.'

Due to emerging information on TCE and developmental effects, MassDEP is incorporating this new information into guidance for public health protection. The new EPA toxicity criterion or oral Reference Dose, is partially based on the developmental toxicity resulting from short term exposures. Most reference doses are based on chronic or long-term exposures. EPA Headquarters has not issued guidance on how to apply this reference dose to response to environmental contamination situations such as TCE in indoor air at hazardous waste sites. As a result, MassDEP has worked to provide TCE guidance for the protection of the developing fetus.   

MassDEP Workplan:

  • Review the scientific literature on TCE and developmental effects and consider the weight of the evidence and dose response relationships for use in risk assessment.
  • Prepare guidance levels for protecting public health from TCE exposures at hazardous waste sites, taking into account the EPA 2011 Reference Dose and Reference Concentrations.
  • Review and compare anticipated guidance from EPA with MassDEP’s and make modifications as determined necessary.
  • Prepare guidance for water suppliers on the new information on TCE risks.

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