Karen Wetterhahn

Karen Elizabeth Wetterhahn (October 16, 1948 – June 8, 1997) was an American professor of chemistry at Dartmouth College, New Hampshire who specialized in toxic metal exposure. She died of mercury poisoning 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 absorbed through the gloves proved to be fatal after less than a year.

Karen Wetterhahn
Born(1948-10-16)October 16, 1948
Plattsburgh, New York, U.S.
DiedJune 8, 1997(1997-06-08) (aged 48)
Lyme, New Hampshire, U.S.
Known forWork on toxic metal exposure
Dying of toxic metal exposure
Scientific career
FieldsChemistry
InstitutionsDartmouth College
InfluencedChristine Alewine

Career

Wetterhahn was born in Plattsburgh, New York, and had degrees from St. Lawrence University and Columbia University.[1] She joined Dartmouth's faculty in 1976 and published more than 85 research papers.[1] In 1990, 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.[1][2][3]

Accident and death

On August 14, 1996, Wetterhahn, a specialist in toxic metal exposure, was studying the way mercury ions interact with DNA repair proteins, and she was investigating the toxic properties of another highly toxic heavy metal, cadmium. She was using dimethylmercury, at the time the standard internal reference for 199Hg nuclear magnetic resonance (NMR) measurements[4] Her death prompted consideration of using an alternative reference material for mercury NMR spectroscopy experiments.[5][6][7]

Wetterhahn would recall that she had spilled several drops of dimethylmercury from the tip of a pipette onto her latex-gloved hand.[8] Not believing herself in any immediate danger, as she was taking all recommended precautions,[9] she proceeded to clean up the area prior to removing her protective clothing.[8] However, tests later revealed that dimethylmercury can, in fact, rapidly permeate different kinds of latex gloves and enter the skin within about 15 seconds.[4] The exposure was later confirmed by hair testing, which showed a dramatic jump in mercury levels 17 days after the initial accident, peaking at 39 days, followed by a gradual decline.[8]

Approximately three months after the initial accident Wetterhahn began experiencing brief episodes of abdominal discomfort and noted significant weight loss. The more distinctive neurological symptoms of mercury poisoning, including loss of balance and slurred speech, appeared in January 1997, five months after the accident.[8] At this point, tests proved that she had a debilitating mercury intoxication.[2][3][9] Her blood and urinary mercury content were measured at 4,000 µg L−1[4] and 234 µg L−1, respectively – both are well above their respective toxic threshholds of 200 µg L−1 and 50 µg L−1 (blood and urine reference ranges are 1 to 8 µg L−1 and 1 to 5 µg L−1).[8]

Despite aggressive chelation therapy, her condition rapidly deteriorated. Three weeks after the first neurological symptoms appeared, Wetterhahn lapsed into what appeared to be a vegetative state punctuated by periods of extreme agitation.[8] One of her former students said that "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."[9] Wetterhahn was removed from life support and died on June 8, 1997, less than a year after her initial exposure.[8]

The case proved that the standard precautions at the time, all of which Wetterhahn had carefully followed, were inadequate for a "super-toxic" chemical like dimethylmercury.[8] In response, the Occupational Safety and Health Administration recommended that the use of dimethylmercury be avoided unless absolutely necessary and mandating the use of plastic-laminate gloves (SilverShield) when handling this compound.[10]

Legacy

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.[4][8] As a result, it is now recommended to wear plastic laminate gloves when handling dimethylmercury.

At the time, dimethylmercury was the common calibration standard for 199Hg NMR spectroscopy because it has certain advantages over the alternatives that exist.[11] As a consequence of Wetterhahn's accident, safety recommendations have been revised, and the use of dimethylmercury for any purpose has been highly discouraged.[10] Wetterhahn's legacy includes a significant and lasting improvement in laboratory safety.[12]

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.[13] 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.[14]

References
  1. "Karen Wetterhahn; Dartmouth Scientist". Los Angeles Times. June 12, 1997. Archived from the original on July 14, 2014. Retrieved July 11, 2014.
  2. Endicott, Karen (April 1998). "The Trembling Edge of Science" (PDF). Dartmouth Alumni Magazine. Archived from the original (PDF) on 2014-07-15.
  3. "A Tribute to Karen Wetterhahn". Dartmouth College. May 1, 2009. Archived from the original on June 26, 2009.
  4. Cotton, Simon (October 2003). "Dimethylmercury and Mercury Poisoning: The Karen Wetterhahn story". Molecule of the Month. Bristol University School of Chemistry. doi:10.6084/m9.figshare.5245807. Archived from the original on April 17, 2012. Retrieved January 6, 2021.
  5. Zacks, Rebecca (September 1997). "Looking for alternatives". Scientific American. Vol. 277 no. 3. p. 20.
  6. Blayney, Michael B.; Winn, John S.; Nierenberg, David W. (May 12, 1997). "Handling dimethylmercury". Chemical & Engineering News. Vol. 75 no. 19. p. 7. doi:10.1021/cen-v075n019.p007.
  7. Toriba, Taft Y.; Clarkson, Thomas W.; Nierenberg, David W. (June 16, 1997). "More on working with dimethylmercury". Chemical and Engineering News. Vol. 75 no. 24. p. 6. doi:10.1021/cen-v075n024.p006.
  8. Nierenberg, David W.; Nordgren, Richard E.; Chang, Morris B.; Siegler, Richard W.; Blayney, Michael B.; Hochberg, Fred; Toribara, Taft Y.; Cernichiari, Elsa; Clarkson, Thomas (1998). "Delayed Cerebellar Disease and Death after Accidental Exposure to Dimethylmercury". New England Journal of Medicine. 338 (23): 1672–1676. doi:10.1056/NEJM199806043382305. PMID 9614258.
  9. Newman, Cathy (May 2005). "Pick Your Poison—12 Toxic Tales". National Geographic. Archived from the original on 2009-02-18. Retrieved 2009-03-07.
  10. Witt, Steven F. (March 9, 1998). "Dimethylmercury". OSHA Hazard Information Bulletins. Office of Science and Technology Assessment, Occupational Safety and Health Administration. Retrieved January 6, 2021.
  11. O'Halloran, Thomas V.; Singer, Christopher P. (March 10, 1998). "199Hg NMR Standards". Northwestern University. Archived from the original on June 3, 2013.
  12. Cavanaugh, Ray (February 2019). "The dangers of dimethylmercury". Chemistry World. Royal Society of Chemistry. Retrieved January 6, 2021.
  13. "The Karen E. Wetterhahn Graduate Fellowship in Chemistry". Dartmouth College. January 30, 2014. Archived from the original on July 10, 2015. Retrieved July 15, 2014.
  14. "Karen Wetterhahn Memorial Award". National Institute of Environmental Health Sciences. June 27, 2013. Archived from the original on August 14, 2012. Retrieved July 14, 2014.
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