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Updated: Jun. 22, 2016

Human Health and Toxicology

 

Limited information is available on the long-term health effects of sulfolane. In 2009, when sulfolane was first discovered in drinking water wells, DEC asked the Department of Health and Social Services (DHSS) as well as the Agency for Toxics Substances and Disease Registry (ATSDR) for assistance in establishing a safe drinking water level. As a result, both agencies conducted health consultations:

 

 

Until a cleanup level is set, Flint Hills is obligated to continue to provide alternative drinking water to impacted residents. The company currently provides alternative drinking water to an estimated 1,500 people affected by the sulfolane plume.

 

 

Summary of health recommendations From DHSS


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.

These summarized recommendations appear on p. 2 in the Sulfolane Update newsletter of June 2014 (pdf file). Other related documents are available below.

 

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National Toxicology Program


 

 

The National Toxicology Program Initiates Long-Term Toxicity Studies

The NTP has embarked on toxicology studies for sulfolane that will 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. The Division is convinced that the right approach in these circumstances is to allow the NTP studies to proceed to conclusion before deciding on a final cleanup level. (See Fact sheet on the NTP studies, June 2015.)

 

In 2011 the State of Alaska recommended the nomination of sulfolane into the National Toxicology Program. The NTP is a federal interagency effort of the National Institutes of Health, the Center for Disease Control and Prevention, and the Food and Drug Administration, to safeguard public health by conducting cutting-edge toxicity research on chemicals.

 

In early 2012, sulfolane was officially accepted into the program. After a preliminary study was nearly completed, the NTP informed DEC in December 2014 that studies to evaluate the long-term health effects of exposure to sulfolane would begin shortly. The long-term (2-year) study was initiated in May 2015.

 

The status of the NTP studies, as of June 2016:

1. 28-Day Toxicity Study – Nearing Completion

Mice, rats and guinea pigs were given a range of doses of sulfolane. A number of toxicity endpoints were assessed including the amount of sulfolane in the animals. Histology of multiple tissues and immunology were also evaluated. Goals of this study were to

1) determine if any of the animal species studied is more sensitive to sulfolane toxicity than the other species, and

2) identify appropriate dosing levels for longer duration studies.

2. ADME Study – Ongoing

Studies measure the absorption, distribution, metabolism, and excretion (ADME) of a chemical in male and female mice and rats. ADME studies help understand how a chemical moves around within the body including whether there are any differences between sexes or rodent species.

3. Subchronic Toxicity Study – Data Evaluation Currently Underway, Began Spring 2015

Mice and rats from the 2-year study were assessed after 3 months of exposure. The study looks at effects on a number of toxicity endpoints including markers of development in the rats. In a separate study, the immune system of rats and mice exposed to sulfolane for 3 months will be evaluated.

4. Two-year, Chronic Toxicity Study – Currently Underway, Began Spring 2015

Rats and mice will be given sulfolane in their drinking water for 2 years, consistent with how people would most likely come in contact with sulfolane. The purpose of this study is to determine the effects of long-term exposure to sulfolane including any potential carcinogenic effects. The NTP will do a limited assessment of pregnancy outcomes in rats.

Useful links:

 


For contact information, please click here.

 

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Human Health and Toxicology:  Project Documents and Reports

Description
Posted
Download

Fact Sheet: The National Toxicology Program's Research on Sulfolane, June 2015
Alaska Department of Environmental Conservation

The NTP has embarked on toxicology studies for sulfolane that will address questions regarding long-term exposure to the solvent, as well as other research gaps.

6/9/15
pdf104K

Report of the Expert Peer Review of Sulfolane Reference Doses for the Alaska Department of Environmental Conservation, December 2014

TERA (Toxicology Excellence for Risk Assessment)
Report on an independent, expert peer review of the available reference doses (RfDs) for sulfolane. The peer review meeting was held September 16 and 17, 2014 in Fairbanks, Alaska. 

 

See TERA's website on the Independent Expert Peer Review of Sulfolane Reference Doses for ADEC.

12/22/14
Vol. 1pdf 522K,
Vol. 2-Appendicespdf 5MB,
Vol. 3- Documentation & Comments)pdf15MB

Report: Garden Soil Sampling, March 2014,
ERM

Results of soil samples from lawns and flower gardens in the North Pole area watered with sulfolane-laden water. No sulfolane was detected, indicating that the use of sulfolane-contaminated water at these locations did not leave residual sulfolane in the soil.

6/5/14

Report, Tables onlypdf378K

 

Report with all Attachments pdf4MB

Fact Sheet: Sulfolane Groundwater Contamination in North Pole: Health Recommendations and Next Steps, June 2013 (Contact info updated December 2014)

Alaska Department of Health and Social Services, Division of Public Health, Section of Epidemiology, Environmental Public Health Program.

7/8/13
242K
EPA Provisional Peer-Reviewed Toxicity Values for Sulfolane (CASRN 126-33-0), Jan. 30, 2012.
U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Superfund Health Risk Technical Support Center.
11/27/12
pdf icon 637K
DHSS Health Consultation - Sulfolane Plume in Groundwater: Evaluation of Community Concerns about Sulfolane in Private Water Wells, Jan. 19, 2012
Alaska Department of Health and Social Services, Division of Public Health, Section of Epidemiology, Environmental Public Health Program.
1/19/12
pdf icon 792K

National Toxicology Program Board of Scientific Counselors, Summary Minutes, December 15, 2011, National Institute of Environmental Health Sciences, Research Triangle Park, NC

 

Minutes from the review of the concept, at the meeting of the NTP's Board of Scientific Counselors - see page 8.

6/22/16
pdf icon 218K

Presentation on sulfolane at the NTP Board of Scientific Counselors Meeting, Dec. 15, 2011, by Chad Blystone, Ph.D., D.A.B.T. National Institute of Environmental Health Sciences

6/22/16
pdf icon 532K
ATSDR Health Consultation on Sulfolane, May 2, 2011
Agency for Toxic Substances and Disease Registry, Emergency Response Team.
5/2/11
pdf icon 402K
Final Results of the North Pole Garden Sampling Project, Jan. 18, 2011 (contact info updated 1/8/2014)
Alaska Department of Health and Social Services, Division of Public Health, Section of Epidemiology.
1/18/11
pdf 69K
Results of the North Pole Garden Sampling Project: Testing of Early Harvest Plants for Sulfolane, Aug. 16, 2010
Alaska Department of Health and Social Services, Division of Public Health, Section of Epidemiology.
8/16/10
pdf icon41K
Community Health Concerns about Sulfolane, April 22, 2010
Alaska Department of Health and Social Services, Division of Public Health, Section of Epidemiology.
4/22/10
pdf icon152K
ATSDR Health Consultation on Sulfolane, Feb. 3, 2010
Agency for Toxic Substances and Disease Registry, Emergency Response Team.
2/8/10
pdf icon772K
Companion Guide to ATSDR's Health Consultation on Sulfolane, Feb. 9, 2010
Alaska Department of Health and Social Services, Division of Public Health, Section of Epidemiology.
2/9/10
pdf icon51K
Sulfolane Health Fact Sheet, Jan. 12, 2010
Alaska Department of Health and Social Services, Division of Public Health, Section of Epidemiology.
1/12/10
pdf icon17K
Reference Materials
Particle Size Distribution and Inhalation Dose of Shower Water Under Selected Operating Conditions, April 2007
Inhalation Toxicology, April 2007, volume 19(4), pages 333-342. Yue Zhou, Janet M. Benson, Clinton Irvin, Hammad Irshad and Yung-Sung Cheng, Lovelace Respiratory Research Institute, Albuquerque, New Mexico. (The author manuscript is through the National Institutes of Health Public Access system. The NIH is part of the U.S. Department of Health and Human Services.)
4/13/12
pdf icon1.4MB
Acute Toxicity and Skin Irritant Properties of Sulfolane, 1966 British Journal of Industrial Medicine, 1966, volume 23, pages 302-304. (The British Journal of Industrial Medicine is now published as Occupational & Environmental Medicine.) V.K.H. Brown, L.W. Ferrigan and D.E. Stevenson, from Shell Research Ltd., Tunstall Laboratory, Sittingbourne, Kent, England; received for publication on April 13, 1966.
4/10/12
pdf icon422K
Studies on Toxicokinetics of 3H-Sulfolane in Rat after Oral Administration, 1988
Journal of West China University Medical Society, 1988, volume 19, pages 61-64. Zhu Zhenhua, Gao Ning, Guo Jitong, Sun Mianling, Wu Desheng and Yang Zaichang, of the Department of Environmental Hygiene, West China University Medical school. Also, Li Zhimin and Lei Youdao of the Laboratory of Isotopes, Institute of Atomic Energy, Chinese Academy of Sciences.
2010
pdf icon22K

 

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