Human Health and Toxicology - Sulfolane and PFAS

Updated: May 8, 2023

Soil and groundwater on the former refinery property are contaminated with sulfolane, PFAS (per- and polyfluoroalkyl substances) and petroleum constituents. Sulfolane and PFAS in contaminated groundwater have migrated off the refinery property. DEC issued a Contaminated Groundwater Advisory in November 2018 to property owners within the North Pole piped water expansion area, where many private water wells contain sulfolane and/or PFAS. The advisory assists residents in avoiding unintentional contact with, or spreading of, contamination.

DEC's Contaminated Water Groundwater Advisory

Sulfolane is unique to this site; therefore, this page focuses mostly on the human health and toxicology related to sulfolane.

Overview of Sulfolane
National Toxicology Program
Useful Links

Per- and polyfluoroalkyl substances (PFAS) are a large and complex class of human-made compounds that have a wide-range of toxicities. They are found in some firefighting foams and many consumer products. For information on the toxicity of PFAS, see the following:

Overview of Sulfolane

The public in the affected area has been provided access to alternative water solutions and recently has had the opportunity to connect to the North Pole municipal water system.

In response to the sulfolane contamination, the refinery’s then-owner Flint Hills Resources Alaska (FHRA) began providing affected residents and businesses with alternative drinking water solutions in 2009 under DEC oversight. In February 2017, the State of Alaska, FHRA, and the City of North Pole reached a settlement agreement to expand the City’s piped water system to all improved properties located within the sulfolane plume or in its anticipated migration path. By the end of 2020, all eligible property owners were offered connection to the service and able to phase out the use of contaminated groundwater wells. Most property owners were eligible to connect at no cost, depending upon the land’s location and improvement status. DEC considers a public water system to be the best way to provide clean drinking water to those affected by contamination in groundwater, now and into the future, and encourages residents within the city’s municipal water provision area to connect to the system.

More on the Piped Water Expansion.

In 2009, when sulfolane was first discovered in drinking water wells, DEC asked the Alaska Department of Health and Social Services (DHSS - now the "Alaska Department of Health," or "DOH") as well as the Agency for Toxic Substances and Disease Registry (ATSDR) for assistance in establishing a safe drinking water level. As a result, both agencies conducted health consultations, available through the links below:

In 2012, DHSS released recommendations regarding use of sulfolane-contaminated groundwater. The public in the affected area was provided access to alternative water solutions and recently has had the opportunity to connect to the North Pole municipal water system. Now that the city’s water system expansion is complete, DEC advises against using untreated, contaminated well water that may cause the spread of pollution. Bringing impacted well water to the surface may expose people to the chemicals and/or allow the chemicals to spread onto other properties, sloughs, or ponds.

Residents connected to the city’s water system are also encouraged to use city water for gardening and for raising farm animals.

Contact Information for the Alaska Department of Health:

DOH Division of Public Health
Andrew Cyr
Public Health Specialist
907-269-8054

National Toxicology Program

The National Toxicology Program's Sulfolane Long-Term Toxicity Studies

The National Toxicology Program (NTP), a federal interagency organization, is conducting toxicology studies for sulfolane that address questions regarding long-term exposure to the solvent, as well as other research gaps. Specifically, a two-year study on rats and mice is evaluating the effects of long-term exposure to sulfolane in drinking water and the effects on pregnancy, development and the immune system. For more information on the NTP studies on sulfolane and current status, see the following: