PFAS

Note: This statement was initially posted on the City of Durham's website on March 14, 2023.

Executive Summary
On March 14, 2023, the U.S. Environmental Protection Agency (EPA) announced new draft drinking water standards for a subset of compounds referred to as PFAS. Until now, there have been no drinking water standards for PFAS. The EPA’s proposed drinking water standard includes the Maximum Contaminant Level (MCL), which is designed to be a “not to exceed” limit for drinking water utilities, such as Durham Water Management. 

EPA is proposing to regulate six specific PFAS: PFOS, PFOA, PFHxS, GenX chemicals (also known as HFPO-DA), PFNA, and PFBS with the following enforceable MCLs: 

• 4 parts per trillion for PFOA
• 4 parts per trillion for PFOS
• Hazard Index for combination of PFHxS, GenX, PFNA, and PFBS compounds

As these are proposed drinking water standards, they are not enforceable standards at this time. The EPA will follow the regulatory development process before the proposed MCLs become the final standards water utilities must meet. Upon completion of this process, the EPA’s final drinking water standards may differ from the proposed drinking water standards. 

Durham Water Management has been proactively testing our source water and drinking water for PFAS compounds since 2018. The proposed MCLs for PFOA and PFOS that were announced today – 4 parts per trillion for PFOA and 4 parts per trillion for PFOS – are both above and below the levels found during a range of tests of Durham Water. Our range of results for PFOA and PFOS has been:

• PFOA is 2.4 - 5.5 parts per trillion for tests conducted between February 2018 and August 2023.
• PFOS is 3.7 - 9.2 parts per trillion for tests conducted between February 2018 and August 2023.

We have not detected GenX or PFNA in our source or drinking water. And while we have detected PFHxS and PFBS in our source and drinking water, Durham Water is below the Hazard Index for these combined compounds.

Durham Water Sampling Data

In the coming months, the City of Durham will be diligently engaged in the finalization of PFAS drinking water regulation and determining the best course of action for our community, including assessment of potential sources, as well as options for mitigation and treatment. Additionally, we will be working to identify sources of funding that can help alleviate the cost-burden on Durham Water customers. Durham Water currently meets all state and federal requirements and has already started working to meet the revised drinking water standards in a cost-effective manner.

EPA anticipates finalizing the rule by the end of 2023. The effective date for the final PFOA and PFOS standards is expected between 2026-2028.

Background
The EPA currently has drinking water regulations for more than 90 contaminants; Durham Water consistently meets these requirements. We also monitor for 60 additional compounds on a regular basis. Read more in our Water Quality Report. Providing a clean and safe drinking water supply, and the regulations that protect it, is based on centuries of scientific research. As our collective understanding of safe drinking water evolves, so does our work and the regulations affecting it. 

PFAS stands for perfluoroalkyl and polyfluoroalkyl substances—a group of thousands of man-made chemical compounds in use since the 1940s to make products resistant to high temperatures, water, and stains. The two specific PFAS contaminants the EPA has proposed national drinking water standards for are:

PFOA—Perfluorooctanoic acid
PFOS—Perfluorooctanesulfonic acid
PFHxS—Perfluorohexanesulfonic Acid
GenX Chemicals—Hexafluoropropylene dimer aced (HFPO-DA)
PFNA—Perfouorononanoic acid
PFBS—Perfluorobutanesulfonic acid 

The compounds are believed to have adverse health effects at very low concentrations over a lifetime of exposure. Because of these properties, PFOA and PFOS were phased out of production by U.S. manufacturers in the mid-2000s. However, PFOA and PFOS can still be imported into the U.S. through consumer goods. They also remain in the environment due to decades of industrial pollution and consumer product use. 

According to EPA’s analysis, only 20% of an individual’s exposure to these compounds comes from drinking water. The remaining 80% of a person’s exposure to PFAS comes from consumer goods such as cookware, cosmetics, food wrappings, stain/water-resistant clothing, and carpet and furniture treatments. You can limit your exposure to PFAS compounds (and reduce their prevalence in the environment) by assessing and reducing your exposure in other aspects of your life. (https://cleanwater.org/10-things-you-can-do-about-toxic-pfas-chemicals)

The proposed MCLs for PFOA and PFOS in drinking water are: 

• 4 parts per trillion for PFOA
• 4 parts per trillion for PFOS
• Hazard Index for combination of PFHxS, GenX, PFNA, and PFBS compounds

A Hazard Index is a tool used to evaluate combined risk from exposure to a mixture of contaminants. It is determined by calculating the ratio of the contaminant level in the water to the health-based water concentration (HBWC) and summing this ratio for these four PFAS: PFHxS, GenX Chemicals, PFNA, and PFBS. We will be working to better understand how the index is calculated and what this means for Durham’s water in the coming weeks. At this time, the levels of these four compounds combined does not exceed the EPA's Hazard Index.

Durham Water Sampling Data

We are not aware of a central source for PFAS compounds in our drinking water. Durham Water Management’s two primary sources of water (Little River Reservoir and Lake Michie) are at the top of their watersheds and receive no direct discharges. Given the prevalence and persistence of PFAS, it is likely there is no central source of PFAS compounds, but rather the levels we have found are coming from the environment at-large. 

Going Forward
In the coming months, the City of Durham will be engaged in the finalization of PFAS drinking water regulation and determining the best course of action for our community, including assessment of potential sources, as well as options for mitigation and treatment. Additionally, we will be working to identify sources of funding that can help alleviate the cost-burden on Durham Water customers. 

It is important to repeat that the proposed PFAS MCLs are not enforceable drinking water standards at this time. If and when the lower limits are finalized, it will require time to determine and fund efforts to meet the revised limits. During this time, residents with high levels of vulnerability may want to assess strategies to reduce their exposure to PFAS compounds. (https://epi.dph.ncdhhs.gov/oee/pfas/PFAS_TestingFiltration.pdf)

The EPA will follow the regulatory development process before the proposed MCLs become the final standards water utilities must meet. Upon completion of this process, the EPA’s final drinking water standards may differ from what has been proposed today. 

The effective date for the final PFOA and PFOS standards is expected between 2026-2028.

Durham Water meets all state and federal regulations for drinking water, and we will continue to monitor and participate in PFAS testing and regulation and will keep the public apprised on this issue. 

If you have any questions or concerns, please contact Joe Lunne at [email protected].