Karen Wetterhahn bigraphy, stories - American chemist

Karen Wetterhahn : biography

October 16, 1948 - June 8, 1997

Karen Wetterhahn (October 16, 1948 – June 8, 1997) was a professor of chemistry at Dartmouth College, New Hampshire, who specialized in toxic metal exposure. She made national headlines when mercury poisoning claimed her life at the age of 48 due to accidental exposure to the organic mercury compound dimethylmercury (Hg(CH3)2). Protective gloves in use at the time of the incident provided insufficient protection, and exposure to only a few drops of the chemical proved to be fatal after less than a year.


Wetterhahn, a specialist in toxic metals, was accidentally poisoned in her lab by a few drops of the toxic, colorless compound, which penetrated her protective glove. On August 14, 1996, Wetterhahn was studying the way mercury ions interact with DNA repair proteins, and was using dimethylmercury as a standard reference material for 199Hg NMR measurements. Dimethylmercury is a synthetic compound used almost exclusively as a reference standard in a particular type of specialized chemical analysis. Wetterhahn was investigating the toxic properties of another highly toxic heavy metal, cadmium, and was using dimethylmercury as a point of reference.

The accidental spill occurred on August 14, 1996, but symptoms of her mercury poisoning were not detected until six months later, by which time the poisoning was irreversible. Wetterhahn suddenly became very ill in January 1997 and was hospitalized; she then went into a coma which lasted until June, at which point she was taken off life support and died.

Wetterhahn recalled that she had spilled several drops of dimethylmercury from the tip of the pipette onto her latex gloved hand. The exposure was later confirmed by hair testing, which showed a dramatic jump in mercury 17 days after exposure followed by a gradual decline. Tests later showed that dimethylmercury can rapidly permeate different kinds of latex gloves and enter the skin within about 15 seconds.

Five months after the exposure, it became evident that some initial serious neurological symptoms such as loss of balance and slurred speech were the result of a very serious debilitating mercury intoxication.Newman, Cathy National Geographic May 2005 She was admitted to the hospital, where it was discovered that the single exposure to dimethylmercury had raised her blood mercury level to 4,000 micrograms per liter, or 80 times the toxic threshold. Her urinary mercury content had risen to 234 µg per liter; its normal range is from 1 to 5 and the toxic level is > 50 μg/L.

Despite aggressive chelation therapy, her condition rapidly deteriorated; three weeks after the first symptoms appeared, Wetterhahn fell into a coma. One of her former students described it as not being "... the kind of coma I'd expected... She was thrashing about. Her husband saw tears rolling down her face. I asked if she was in pain. The doctors said it didn't appear that her brain could even register pain." Wetterhahn died a few months later, less than a year after her initial exposure.

There had been previous documented cases of death due to dimethylmercury poisoning. In 1865, two English laboratory assistants died several weeks after helping to synthesize dimethylmercury for the first time. In 1972, a 28-year-old chemist in Czechoslovakia had suffered the same symptoms as Wetterhahn after synthesizing 6 kg of the compound.


Karen Wetterhahn's death shocked not only the entire chemistry department at Dartmouth, but also regulatory agencies, as the accidental exposure occurred despite her having taken all required measures known at that time. These included the use of latex gloves, a fume hood, and adherence to standard safety procedures. After Wetterhahn's mercury poisoning was discovered, her colleagues tested various safety gloves against dimethylmercury and found that the small, apolar molecule diffuses through most of them in seconds, much more quickly than expected. As a result, it is now recommended to wear highly resistant, flexible, plastic-laminate gloves when handling dimethylmercury and other similarly dangerous substances. For increased protection, such thin gloves can be worn under long-cuffed, heavy-duty outer gloves made of, for example, neoprene.

At the time, dimethylmercury was the common calibration standard for 199Hg NMR spectroscopy because it has certain advantages over the alternatives that exist.]] As a consequence of Wetterhahn's accident, recommendations], February 15, 1991] and MSDS sheets[https://fscimage.fishersci.com/msds/99021.htm Material Safety Data Sheet: Dimethylmercury] have been revised, and the use of dimethylmercury has been highly discouraged.

Dartmouth College has since established an award in Wetterhahn's name to encourage other women to pursue careers in science. Whenever possible, preference in granting the award is given to a woman. The National Institute of Environmental Health Sciences also maintains an annual award, for a graduate student or post-doctoral researcher, in honor of Karen Wetterhahn.]]

Wetterhahn helped establish Dartmouth College’s Women in Science Project (WISP), which helped to raise the share of women science majors from 13 to 25 percent at Dartmouth College and has become a national model.

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