Deptartment of Environment & Natural Resources
For Immediate Release: Friday, August 2, 2002
For More Information: Tim Tollefsrud, 773-3153

Background on MEK

PIERRE – Recent news stories have reported that CoEv employees in Watertown dumped methyl ethyl ketone (MEK) on or near a concrete pad beside its building.  People have questioned, what is MEK?   

MEK, also known as 2-Butanone, is a clear, colorless, volatile, and highly flammable liquid that has a sharp, sweet odor.  Wastewater containing MEK is listed by federal regulations as a hazardous waste because of MEK’s volatility and flammability.  

MEK is manufactured in large quantities as an ingredient in protective coatings, such as paints and adhesives.   It is also used in the processing of foodstuffs and food ingredients.

Foodstuffs that can contain MEK include cheese, white bread, tomatoes, fish, fruits, vegetables, cooked turkey breast, honey, coffee, milk, carrots, potato chips, yogurt, apple juice, and others.  MEK can also be found in cigarette smoke.  In one study, the mean concentration of MEK found in dried beans, split peas, and lentils was 148,000, 110,000, and 50,000 parts per billion, respectively.  The average daily intake by a United States citizen is about 1.6 milligrams per day.  

MEK does not stay in your body for very long, as it will generally be gone by the next day.  The bulk of MEK absorbed or ingested by humans is transformed into compounds like carbon dioxide and water by the general metabolism process. 

MEK also occurs naturally and has been found in many plants and insects.  Trees such as junipers, cedars, cypress trees, and ferns emit MEK.  It is also emitted into the atmosphere through the exhaust systems of cars.  Monitoring around Los Angeles has found concentrations of MEK as high as 43.5 parts per billion in the air that people breathe.  

Because there is no drinking water standard for MEK, DENR staff asked Robert Benson, Ph.D., toxicologist with the U.S. Environmental Protection Agency, to calculate a risk based advisory level for MEK in drinking water.  Dr. Benson calculated what is called a Lifetime Health Advisory level.  A Lifetime Health Advisory level is the amount of a chemical that people can drink every day of their life, and not have any adverse health effects.  Dr. Benson calculated that a person could drink two liters of water containing up to 4,200 parts per billion of MEK during every day of their life, and not have any adverse health effects.  Dr. Benson also stated the primary health effect that may be caused by drinking water containing MEK above this level would be decreased fetal weight.  

Trace amounts of MEK have been detected widely in drinking water wells all over the country.  The primary source of the trace amounts of MEK in drinking water wells is leaching of MEK from the adhesives used to join the plastic pipes in the well.  

MEK is highly mobile in the natural environment and mixes well with water, but it also evaporates very quickly.  One study on MEK in ground water found that all of the MEK had completely evaporated in 14 days.  According to the federal Agency for Toxic Substance and Disease Registry, once released to the environment, one-half of the MEK will break down when exposed to sunlight in 24 hours or less.  

Inhalation of MEK poses one of the largest risks, but primarily with workers that are exposed to the fumes generated by the solvents in manufacturing.  MEK fumes are irritating to the lungs, skin and eyes.  Because of these irritating properties, the Occupational Safety and Health Administration has set an occupational exposure limit of 200,000 parts per billion in the air to protect workers.  However, you can smell MEK at 5,000 parts per billion, which is well before it reaches toxic levels. 

Many studies have been conducted on various animals to determine the toxicity of MEK.  Effects observed during studies where animals have been exposed to very high levels of MEK include death, irritation of respiratory tissue, eyes and skin, liver congestion, kidney congestion, corneal opacity, narcosis, incoordination, and fetotoxicity.  However, none of these effects have been linked to humans exposed to MEK.

So, what does all this mean?  On July 31, 2000, CoEv’s consultant Earth Tech drilled four soil borings near where the MEK was dumped on the ground and took ground water and soil samples from the borings.  MEK was found in the water in two of the borings at levels of 480,000 parts per billion and 37 parts per billion. MEK was also detected in two soil samples in two of the borings about four feet below ground surface.  The concentrations found in the two soil samples were eight and 24 parts per billion.  Over the next 18 months, DENR instructed CoEv to determine the extent of contamination.  CoEv had its consultant drill 18 more borings to check for soil contamination and install four wells to monitor the ground water.   During these 18 months, all soil and ground water samples collected and tested for MEK were below laboratory detectable levels.  

Based on all the soil and ground water monitoring samples that showed MEK at the site was below laboratory detection levels, DENR closed out the site.  Because of its highly volatile characteristics, DENR believes all the MEK either evaporated or degraded and no MEK is left. 

“While the data collected thus far has shown that MEK has not been found anywhere other than the immediate vicinity of where the dumping occurred, DENR wants to assure residents in the area the water from their private wells is safe to drink,” said DENR Secretary Steve Pirner.  

As one assurance, if anyone has a private well near CoEv they would like sampled for MEK, contact Jay Cofer, with the DENR regional office in Watertown, at (605) 882-5111.  

As a second assurance to local residents, DENR plans to drill monitoring wells south of CoEv on the south side of Highway 212.  The wells will be drilled by the South Dakota Geological Survey on August 6, 2002, starting at 9:30 a.m. as part of a planned event to let South Dakota citizens know about information available on the state’s ground water and on the Geological Survey’s drilling capabilities.

The following sources were used in writing this press release:

Toxicological Profile for 2-Butanone.  U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substance and Disease Registry.  July 1992.

Environmental Health Criteria 143 Methyl Ethyl Ketone.  Published under the joint sponsorship of the United Nations Environment Programme, the International Labour Organisation, and the World Health Organization.  1993.  The document can be found on the Internet at http://www.inchem.org/documents/ehc/ehc/ehc143.htm#SectionNumber:4.1 .  

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