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Karen Wetterhahn

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Karen Wetterhahn (October 16, 1948 – June 8, 1997) was a well-known 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]). She was the Albert Bradley Third Century Professor in the Sciences at Dartmouth College.

Accident

On August 14th, 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.[1]

Wetterhahn, a specialist in toxic metals, was poisoned in her lab by a few drops of the rare, extremely toxic, colorless compound, which accidentally penetrated her protective glove. 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 merely using dimethylmercury as a point of reference when the surprising poisoning occurred.

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

She recalled that she had spilled several drops of dimethylmercury from the tip of the pipette onto her latex gloved hand. Tests later showed that this can rapidly permeate different kinds of latex gloves and enter the skin within about 15 seconds.[2][1]

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.[3][4][5] 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 1 to 5 and the toxic level is > 50 μg/L.[2]

Despite aggressive chelation therapy, her condition rapidly deteriorated and three weeks after first symptoms appeared she fell into a coma described by one of her former students 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."[5] 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 Czech chemist in Czechoslovakia had suffered the same symptoms as Wetterhahn after synthesizing large amounts of the compound.[2][3]

Legacy

Karen Wetterhahn's death shocked not only the entire chemistry department but even regulatory agencies, as the accidental exposure occurred despite 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 faster than expected. As a result, it is nowadays recommended to wear highly resistant, flexible, plastic-laminate gloves when handling dimethylmercury and other equally dangerous substances. For increased protection, such thin gloves can be worn under long-cuffed, heavy-duty outer gloves made of, for example, neoprene.[2][1]

At the time, dimethylmercury was the common calibration standard for 199Hg NMR spectroscopy because it has certain advantages over the alternatives that exist.[6] As a consequence of Wetterhahn's accident, recommendations[7] and MSD sheets[8] have been revised, the use of dimethylmercury has been highly discouraged, and its sale is now prohibited.

Dartmouth College has since established an award in Wetterhahn's name to encourage other women to pursue careers in science. Whenever possible, preference is given to a woman in granting the award.[9] 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.[10]

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.[3]

References

  1. ^ a b c Simon Cotton: "The Karen Wetterhahn story"
  2. ^ a b c d Nierenberg D. W. et al. "Delayed Cerebellar Disease and Death After Accidental Exposure to Dimethylmercury." The New England Journal of Medicine 1998, 1672–1676.
  3. ^ a b c The Trembling Edge of Science, DARTMOUTH ALUMNI MAGAZINE - APRIL 1998
  4. ^ A Tribute to Karen Wetterhahn
  5. ^ a b Newman, Cathy "Pick Your Poison—12 Toxic Tales National Geographic May 2005
  6. ^ 199Hg NMR Standards OSHA
  7. ^ Hazard Information Bulletin—Dimethylmercury, Occupational Safety and Health Administration, February 15, 1991
  8. ^ Material Safety Data Sheet: Dimethylmercury
  9. ^ [1]
  10. ^ Karen Wetterhahn's Memorial Award, National Institute of Environmental Health Sciences

See also

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