Karen E. Wetterhahn, Ph.D., (October 16th, 1948 -
June
8th, 1997) was a research professor of chemistry at Dartmouth
College
and world-renowned expert in the field of metal toxicology. Wetterhahn
was born
in Plattsburgh, New York, and received bachelor's
degrees in
chemistry and mathematics from St. Lawrence University in 1970. In
1975, she
received her doctorate in inorganic chemistry and physical
biochemistry from Columbia University. A year later, she became the
first female professor of chemistry at Dartmouth University.
Wetterhahn served as dean of graduate studies in 1990, taking on the
role of
associate dean of the faculty for the sciences from 1990 to 1994, and
serving
as acting dean of the faculty of arts and sciences in 1995.
On August 14th, 1996, Wetterhahn was working with dimethylmercury, a
substance known even then for its potent toxicity. As was the standard lab
safety protocol, Wetterhahn wore latex gloves, goggles, and a protective lab
coat; as a further precaution, her work with the exposed dimethylmercury was
carried out inside a chemical fume hood, to reduce the danger of the chemical's
vapors. Using a pipette, Wetterhahn extracted the dimethylmercury from its
ampule, placing some inside a sample tube and the rest in a storage vial. In
the process, a drop or two of the dimethylmercury dripped from the pipette,
landing on Wetterhahn's latex glove. Despite this, there were no visible
indications that the chemical had breached the glove's material. After
finishing her work, Wetterhahn peeled off her gloves, washed her hands
thoroughly, and went home.
Five months after the incident, Karen Wetterhahn began to experience
an
unusual dizziness and a slurring of her speech. Following the advice
of a
friend, Wetterhahn admitted herself to the Dartmouth-Hitchcock Medical
Center; a neurologist
confirmed that her symptoms suggested a case of mercury poisoning.
After
further blood and urine analysis, the diagnosis was confirmed to be
"Severe
Mercury Toxicity". Wetterhahn's vision and hearing were both beginning
to
degenerate at the time she began chelation therapy. On February 6th,
1997, Wetterhahn fell into a coma. She died on June 8th, 1997.
In the wake of Wetterhahn's poisoning, it became clear to her Dartmouth colleagues that
the scientific community's understanding of dimethylmercury and the true scope
of its toxicity were grossly inadequate. After all, the materials safety data sheet,
provided by the supplier from whom Wetterhahn had purchased the
dimethylmercury, specifically recommended rubber gloves as suitable protection. Alarmingly, they found that
there had been no permeability testing to validate this recommendation in the
first place. At the behest of John Winn, chairman of the Dartmouth
chemistry department, and Michael Blayney, Dartmouth College's
health and safety director, a half-dozen or so different gloves from
Wetterhahn's lab were sent to be tested. The results indicated that dimethylmercury took less than fifteen seconds to
permeate latex gloves; the other gloves tested were, likewise, determined to be
useless as a means of protection. Only a multi-layered
laminate glove proved effective, withstanding dimethylmercury for up to four
hours. The story of Wetterhahn's accident, the glove permeability data, and
the safety recommendations derived from it were published in the May 12th, 1997
edition of Chemical and Engineering News.
Of course, the erroneous recommendation was really,
itself, the symptom of a more fundamental misunderstanding within the
scientific
community, regarding dimethylmercury's potential toxicity. The
disparity, explained Winn, can be plainly seen between typical mercury
poisoning (in which
50 micrograms of mercury per liter of blood constitutes the
toxic threshold) and an analysis of Wetterhahn's blood, which was found
to contain 4,000 micrograms per
liter—in other words, 80 times the toxic threshold, produced from only a
drop
or two of the substance. And yet, despite its overwhelming toxicity,
dimethylmercury had only been involved in two fatal accidents prior to
Wetterhahn's. The first incident, in 1865, resulted in the deaths of the
two
English chemists responsible for synthesizing the compound; both died
from exposure to the chemical’s fumes. The second accident occurred in
1970, leading to the death of a Czech scientist. This discrepancy
between the
compound’s lethality and its history led, at first, to an air of
incredulity amongst the scientific community in the aftermath of
Wetterhahn's accident; with dimethylmercury's widespread use throughout
the last one-hundred years, it seemed highly unusual that more people
hadn't fallen
victim to it's toxicity.
At the time, dimethylmercury was still widely used by scientists,
particularly in experiments examining the effects of mercury on
living cells. To analyze these effects, scientists observe the
bonded changes within the cell's
structure through the use of an NMR (nuclear magnetic
resonance) spectrometer, which returns a pattern of
frequencies
representing the molecule's form. However, a change in the cell's
structure is only noticeable when
compared to the frequencies of a standard, which is, furthermore,
necessary to
calibrate the machine before testing. Dimethylmercury, despite its
toxicity, is an ideal standard for mercury testing, and it was for this
reason that Karen
Wetterhahn, on the day of the accident, had been preparing a sample of
dimethylmercury. In a last, bitter irony, Wetterhahn had previously
used mercury
chloride salts as the standard for her work with the NMR spectrometer,
but opted to use the
dangerous, but more accurate dimethylmercury only after expressing
dissatisfaction with the mercury chloride results. After completing the
experiments a second time with the dimethylmercury standard, however,
Wetterhahn was surprised to find that the results only confirmed the
accuracy of her initial tests.
Yet, inspite of the tragic circumstances of her death, it's Karen
Wetterhahn's life and work which continues to exert a lasting influence
on both Dartmouth and the scientific community. Within her field,
Wetterhahn was primarily known for her work in chromium
carcinogenesis, of which she was one of the world's leading
authorities. Among her
contributions, she introduced the concept known as the uptake-reduction
model,
to explain the process by which chromium damages DNA. And, at the time
of her death, she had authored over 85 research papers. In
1991, Wetterhahn established the Women in Science Project alongside
Carol
Miller, assistant dean of engineering, to address the disproportionate
amount
of female students dropping out of science related fields. As a result,
the
percentage of female science majors has doubled in size. She further
served as an officer for the
Women in Cancer Research Society, as well as a past officer in the
American
Association for Cancer Research. As to her character, much has been
said about
her personal enthusiasm, her good-natured approach to collaboration, and
her
passion for science. John Winn, in remembering his colleague, remarked
that
"I always heard her laughing – I never heard her yelling. For the most
part, I’ll remember her
giggle"(8).
Karen Wetterhahn is survived by her husband Leon Webb, and her two children
Leon Jr. and Charlotte.
In memory of Karen Wetterhahn, Dartmouth has established a
graduate fellowship in chemistry and an annual faculty achievement
award in her
honour. Furthermore, both a library reading room and the annual
undergraduate
science symposium have been dedicated and named in her memory. Perhaps
even
more subtly, her influence can be felt within the many chemistry
classrooms of Dartmouth, a fact acknowledged by chemistry lab
coordinator Sally Hair: "Most
students wear gloves most of the time now, even when they don’t need to.
We’re
spending a lot on gloves. We’re going through hundreds of pairs per
week"(2).
Sources
- "The Trembling Edge of Science" by Karen Endicott
- Women
in Medicine: An Encyclopedia by Laura Lynn Windsor (2002)
- "Handling dimethylmercury" by Michael B. Blayney, John S. Winn & David W. Nierenberg, Chemical & Engineering News (May 12th, 1997)
- "Colleagues
Vow to Learn From Chemist's Death" by Carey Goldberg, the New York Times
(October 3rd, 1997)
- "Dartmouth Researcher Dies from Mercury Poisoining" Associated Press (June 11th, 1997)
- "A Tribute to Karen Wetterhahn" Dartmouth
- "In Memoriam
Karen E. Wetterhahn, Ph.D. 1948−1997" American Chemical Society
(September 15th, 1997)
- "Remembering
Karen Wetterhahn" by Laura Sternick, Dartmouth (May 16th,
2008)