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Unregulated Drinking Water Contaminants

Unregulated Drinking Water Contaminants

The U.S. Environmental Protection Agency (EPA) sets standards for drinking water quality under the Safe Drinking Water Act (SDWA). EPA has set maximum contaminant levels and/or treatment technique requirements for more than 90 regulated contaminants. The SDWA also requires EPA to look at other unregulated contaminants that may pose a risk to human health.

Contaminant Candidate List and the Unregulated Contaminant Monitoring Rule

The SDWA includes a process EPA must follow to identify and list unregulated contaminants that may require a national drinking water regulation in the future. EPA must periodically publish this Contaminant Candidate List (CCL) and decide whether to regulate at least five or more contaminants on the list.

Under the 1996 amendments to the SDWA, EPA issued the Unregulated Contaminant Monitoring Rule (UCMR) to collect data for contaminants that do not have health-based standards and are suspected to be present in drinking water. EPA selects contaminants for UCMR largely based on the CCL. These selected contaminants are sampled in all large public water systems and in a representative sample of small public water systems serving up to 10,000 people.

Tracking and surveillance of these unregulated contaminants provides a basis for future regulatory actions to protect the public’s health from potential adverse health outcomes related to exposure to the contaminants.

Per and polyfluoroalkyl substances (PFAS)

In 2012, EPA selected six perfluorinated compounds from EPA’s Contaminant Candidate List 3 for the Third Unregulated Contaminant Monitoring Rule (UCMR3):

  • perfluorooctane sulfonic acid (PFOS)
  • perfluorooctanoic acid (PFOA)
  • perfluorononanoic acid (PFNA)
  • perfluorohexane sulfonic acid (PFHxS)
  • perfluoroheptanoic acid (PFHpA)
  • perfluorobutane sulfonic acid (PFBS)

These compounds are part of a family of chemicals known as Per and polyfluoroalkyl substances (PFAS)

PFAS are chemicals that do not occur naturally in the environment. PFAS have unique physical and chemical properties that allow them to repel oil, grease, and water. They have widespread use in industry and consumer products. PFAS have been used in food packaging materials, nonstick cookware, stain resistant carpet treatments, water resistant clothing, cleaning products, paints, varnishes and sealants, fire-fighting foams, and some cosmetics since the 1950s.

There is evidence that exposure to PFAS chemicals can lead to adverse human health effects. Some, but not all, studies have shown that certain PFAS may:

  • affect growth, learning, and behavior of infants and older children
  • lower a woman’s chance of getting pregnant
  • interfere with the body’s natural hormones
  • increase cholesterol levels
  • affect the immune system
  • increase the risk of cancer

Learn more about PFAS.

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