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Human Health and Toxicology - Sulfolane and PFAS

Updated: September 29, 2020

Soil and groundwater on the former refinery property are contaminated with sulfolane, PFAS and petroleum constituents. Sulfolane and PFAS in contaminated groundwater have migrated off the refinery property.

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

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.

Under DEC oversight, in 2009 then-owner of the refinery Flint Hills Resources Alaska (FHRA) began providing affected residents and businesses with alternative drinking water sources. 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. Implementation of the expanded piped water system is expected to be complete by the end of 2020 and will provide permanent protection from contamination in drinking water.

In 2009, when sulfolane was first discovered in drinking water wells, DEC asked the Alaska Department of Health and Social Services (DHSS) 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:

Summary of 2012 SULFOLANE health recommendations From the Alaska department of health and social services

In 2012, DHSS released the following recommendations regarding use of sulfolane-contaminated groundwater. 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.

Residents who have wells with sulfolane detections should continue using an alternative water supply for drinking and for growing edible plants. Edible garden plants can take up sulfolane from water, therefore people can be exposed to sulfolane by consuming produce that has been watered with sulfolane-contaminated water.

Given the concentrations of sulfolane reported to date, residents can still use wells with positive sulfolane detections for most household activities such as bathing, washing clothes and dishes, rinsing foods, and making foods where the water is discarded, such as boiling eggs. Based on currently available information, using well water to shower does not pose a health risk for North Pole residents, although inhaling sulfolane in water droplets during showering needs further evaluation.

Other exposure routes such as breathing vapors or direct skin contact are unlikely to pose a risk because the chemical has low volatility and is not absorbed through the skin.

Residents on the city’s public water system are encouraged to use city water for gardening.

Residents who raise chickens or other animals do not have to worry about sulfolane in their meat or other products (milk, cheese, eggs, etc.) as long as the animals are not drinking water that contains sulfolane.

Contact Information for the Alaska Department of Health and Social Services:

  • DHSS Division of Public Health
  • Sarah Yoder
  • Public Health Specialist
  • 907-269-8054

National Toxicology Program

The National Toxicology Program Initiates Sulfolane Long-Term Toxicity Studies

The National Toxicology Program (NTP). a federal interagency organization, has embarked on toxicology studies for sulfolane that address questions regarding long-term exposure to the solvent, as well as other research gaps. Specifically, the NTP is conducting a two-year study on rats and mice to evaluate 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: 

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