Losing world-class chemist Karen Wetterhahn
to mercury poisoning redrew the boundaries of safety and risk.
DARTMOUTH ALUMNI MAGAZINE - APRIL 1998
The mercury compound Karen Wetterhahn needed looked like
a small vial of water. A mere drop or two proved lethal.
"Sometimes it’s hard to predict the long-term
consequences of doing something. You don’t always have the knowledge you need.
You have to make your best judgment."
—Karen Wetterhahn, 1995
After years of adeptly handling the known risks
of heavy metals, Karen Wetterhan chanced upon the unknown.
Gilbert Fox; all other photos by Joe
- The Wednesday in August that stole
- Karen Wetterhahn’s life seemed to be just another day in the
lab. The chemist needed to transfer a small amount of a chemical
from one container to another. As she always did when working in her
lab, Wetterhahn donned her protective lab coat, goggles, and
disposable latex gloves. Because the chemical she would be working
with that day was dimethylmercury, a highly toxic and volatile
liquid compound, the transfer would be done in a chemical fume hood.
The ventilated hood would place a glass barrier between her and the
mercury and create a convection current to draw vapors away from the
air she would breathe.
Wetterhahn prudently asked her colleague David Lemal to help her
with one part of the procedure—opening the sealed glass vial. Lemal
chilled the vial in ice water to lower the vapor pressure of its
contents. He scored around the top of the ampule with a file, cleanly
snapped the top off, and left the lab. Using a syringe-like pipette,
Wetterhahn drew a small amount of the dimethylmercury out of the vial,
deposited it into a pencil-thin glass sample tube, then pipetted the
rest into a small screw-top storage vial. In the process a drop or two
of the liquid dripped from the pipette onto her left glove. She sealed
and labeled the sample tube and storage vial—dimethylmercury 8/14/96
KEW—peeled off her gloves, left them in the fume hood, then
thoroughly washed her hands. All standard procedures.
Karen Wetterhahn went home to her husband and two children. She
should have gone straight to the hospital. For the dimethylmercury
that had landed on her glove had penetrated the latex and then her
skin and was already beginning a slow, unseen journey into her blood
and into her brain.
But how could she have known this? There were no visible holes in
her glove. The dimethylmercury, clear like water but three times as
dense, hadn’t burned or otherwise announced itself as it seeped into
her skin. Even the wetness of the drop or two would have been
indistinguishable from the clamminess that builds up inside rubber
gloves. There was no reason for Karen Wetterhahn to think that she had
been exposed to dimethylmercury.
Five months later the deliberate, focused, and precise scientist
found herself stumbling into walls and slurring her speech. The woman
who was never sick suddenly was asking her husband to pick her up from
work because she didn’t feel well enough to drive home. She finally
heeded a friend’s admonition to see a doctor. She was admitted to
the hospital at the Dartmouth-Hitchcock Medical Center. When
neurologist Richard Nordgren told her that her symptoms—nausea,
weight loss, loss of balance, and trouble with speech—could be
caused by exposure to mercury, Wetterhahn mentioned the small spill of
dimethylmercury that had happened back in August. Samples of
Wetterhahn’s blood and urine were rushed to a lab for testing. By
the time preliminary reports confirmed the possibility of mercury
toxicity, she was having trouble with her hearing and eyesight. When
more lab results confirmed the diagnosis—severe mercury toxicity—DHMC
clinical pharmacologist David Nierenberg treated her with chelation
therapy. Each day she ingested a medication that would act like a
magnet, attracting the mercury and binding it into a substance her
body could excrete.
As soon as the diagnosis was clear Wetterhahn’s laboratory was
closed. Nierenberg tested Wetterhahn’s family and laboratory
colleagues for mercury. All members of the chemistry department were
given the opportunity to be tested. Wetterhahn asked John Winn,
chairman of the chemistry department, to make sure that the people who
had helped her with the dimethylmercury work were checked. Everyone
who worked with her or had done any recent work with mercury compounds
had the tests done. Everyone tested normal. The College’s Office of
Environmental Health and Safety arranged for a certified industrial
hygiene firm to test the air and surfaces in Wetterhahn’s lab,
office, car, and home. Everything she might have touched was tested,
even doorknobs, light switches, and telephones. The only place mercury
was found was the canister that contained the vial of dimethylmercury
Wetterhahn had used. She was keeping it, in the safety of the chemical
fume hood, until the results of her experiments were accepted for
publication. She was holding onto it in case she needed to repeat or
replicate any part of the experiments. "Why don’t you get rid
of it," Wetterhahn now told Winn. She didn’t want anyone else
to face what she was facing.
The mercury in Wetterhahn’s body was attacking her nervous system
at an alarming rate. Her field of vision kept shrinking. Her hearing
was shutting down. She had to struggle to speak, but she urged Winn
and Nierenberg to do all they could to alert the scientific community
to the dangers of dimethylmercury.
On February 6, barely three weeks from the moment she noticed
anything was wrong, Karen Wetterhahn slipped into a coma.
"Karen had no idea she was in peril,"
says chemistry department chairman John Winn. "None of the chemists
here would have felt in peril."
The three weeks were long enough for the scientists to
understand that their colleague was not coming back. "When we heard
the diagnosis there was almost a sense of relief that we knew what it
was," David Lemal says. "Then we realized the horror of the
irreversibility of the damage." Worse still, they knew that
Wetterhahn knew. "It was obvious that the chelation therapy
wasn’t working. She was a very good metal toxicologist. She knew what
the mercury was doing to her," says Kent Sugden, a post-doctoral
fellow in her research group on chromium. "When she went into a
coma many of us saw it as merciful."
Disposable latex gloves gave Wetterhahn needed
dexterity. No one knew that dimethylmercury soaks through them.
While Wetterhahn lay suspended in the immutable final symptom of
mercury poisoning, her colleagues replayed the steps that had brought
her to this most unforeseen of fates. They tried to make sense of the
facts. They tried to understand how she could have done everything right
but the outcome could have gone so horribly wrong. They kept bumping up
against the limits of what anyone knew about dimethylmercury. The more
they probed the more they realized that when it comes to dimethylmercury,
the line between safety and risk had to be redrawn.
At the beginning nothing made sense. The accident seemed so
improbable as to be impossible. "We’re having professional
shock," Winn said shortly after the diagnosis. "She was doing
routine manipulations." His colleague Russell Hughes was equally
mystified. "She was a careful experimentalist operating in new labs
in a state-of-the-art facility," he says. She had not done anything
unusual or foolish. She had taken the standard precautions: protective
clothing and goggles, working in a chemical fume hood. She had worn
rubber gloves, as standardly recommended. She had chosen the
close-fitting disposable latex kind, like surgeons wear, so she would
have maximum dexterity. "She had no idea she was in peril,"
says Winn. "None of the chemists here would have felt in
What no one knew at the time was that latex gloves are no match for
Chemists routinely consult material safety data sheets compiled by chemical
manufacturer and suppliers for information about protections against specific
chemicals. Three material safety data sheets (MSDS) were available for
dimethylmercury. Alfa Aesar, the chemical supplier from whom Wetterhahn bought
the dimethylmercury, recommended "rubber gloves." Organometallics, the
company that manufactured the dimethylmercury, recommended gloves made of the
synthetic rubber neoprene. Sigma Aldrich, the chemical supplier that produced
the third MSDS, recommended wearing "chemically impervious gloves."
However, "there is no such thing," says the College’s health and
safety director, Michael Blayney. "No glove is completely
impermeable." The rates of permeability vary according to the glove type
and the chemical involved. Despite the recommendations on the material safety
data sheets, Blayney says, no one had actually tested any kind of protective
gloves to see how they stood up to dimethylmercury.
Wetterhahn directed John Winn to warn scientists
about the extreme dangers of dimethylmercury.
After Wetterhahn’s diagnosis, Blayney and Winn initiated such
testing. They approached the National Institute for Occupational Safety
and Health to find out where dimethylmercury permeability testing could
be done, then sent the seven types of disposable gloves found in
Wetterhahn’s lab to Intertek Testing Services for analysis. The
results were shocking. Dimethylmercury raced through latex gloves in 15
seconds or less, possibly even instantaneously. The other types of
disposable gloves from the lab failed as quickly. Only a specialized
multi-layer plastic laminate glove fared well, providing more than four
hours of protection.
Blayney, Winn, and Nierenberg rushed to warn other scientists. In the
May 12 , 1997, edition of the American Chemical Society’s weekly
magazine, Chemical and Engineering News, they published an account of
Wetterhahn’s accident and the results of the glove tests. They
included the first empirically based recommendation for protection when
handling dimethylmercury: "Rubber gloves" were not enough.
Instead, "a highly resistant laminate glove (SilverShield or 4H)
should be worn under a pair of long-cuffed, unsupported neoprene,
nitrile, or similar heavy-duty gloves." Soon sites across the World
Wide Web were repeating the warning.
But back on that day in August Wetterhahn had no idea that she was
Until the accident no one realized that merely a drop or two of
dimethylmercury could prove fatal. "I looked at the amount of
dimethylmercury left in the vial after the transfer and I assumed there
was no way she could have gotten enough of it on her," group member
Sugden recalls. "I thought the poisoning was from her previous work
with mercury salts."
All mercury is toxic, but each form is toxic in its own way.
"You can hold the silvery liquid mercury from a thermometer in your
hand and nothing would happen," says John Winn. "The danger of
liquid mercury is in its vapor." That’s why the mercury from a
broken thermometer should be sponged up, sealed inside a plastic bag,
and taken to a hazardous waste facility rather than vacuumed—vacuuming
disperses the vapors. Other forms of mercury used in industry—for
dyes, in various electronic devices like switches—readily contaminate
waste sites or waterways they enter. The mercury accumulates in fish and
can cause mercury poisoning in anyone who consumes them.
Wetterhahn’s accident showed that dimethylmercury was far more
toxic than anyone thought. "We’re all exposed to mercury just by
being alive," Winn says. "A usual mercury concentration would
be ten micrograms per liter of blood or less. If the level rises to 50
micrograms per liter you’ve hit the toxic threshold, the beginning of
toxicity. You would begin chelation therapy. A concentration of 200
micrograms per liter is toxic, but not necessarily lethal. Karen had
4,000 micrograms per liter. That’s 80 times the toxic threshold."
Merely absorbing a drop or two placed her in the lethal range.
"Everyone knew dimethylmercury was bad," says Sugden.
"No one knew it was this bad."
"On a scale of one to ten, dimethylmercury was a 15," says
chemistry professor Dean Wilcox. "Before Karen’s accident we
thought it was a ten. Now we know it is off the scale."
Scientists have been willing to work around dimethylmercury’s
dangers because the compound happens to be invaluable in various areas
of research, including experiments into how toxic metals damage living
cells. Building on the idea that structure is related to function,
researchers reason that if they want to know how a toxin interferes with
the normal functioning of a cell, they need to know two things: the
structure of the normal cell and the structure of the cell after a toxin
binds to it. By pinpointing which part of the cell structure binds the
toxin, they hope to learn how the toxin changes the cell
functioning—and how that process might be turned off.
If you’ve ever had an MRI, a magnetic resonance image, to get a
three-dimensional fix on a tumor or other medical problem, you are
already acquainted with the kind of spectroscopic technology researchers
like Wetterhahn use to learn about the components of cells. Two nuclear
magnetic resonance spectrometers, research cousins to the MRI, reside in
a first-floor lab at the College’s Burke Laboratory. Like MRIs, these
NMR spectrometers use magnetic fields to detect differences in the
molecular materials they scan. MRIs process the data into recognizable
photographic images of the body. NMR spectrometers are a bit more
cryptic, providing data that can be used to infer rather than photograph
molecular structures. But then, they are measuring differences at the
atomic rather than human level.
"The sample sits in a large magnet," explains chemistry
professor John Bushweller, who regularly uses NMR spectroscopy in his
research on how damage to proteins causes cancer. "You shine radio
frequencies onto the sample to excite the molecules and see how
different atoms react. The signal peaks at certain frequencies,
indicating particular atoms. It’s a bit like finding out the FM
frequency of the molecule."
The frequencies are like signatures when viewed individually. When
compared with the pattern of a standard, however, each signal represents
a shift that has structural significance. The standard is like sea
level, explains Winn, and each shift indicates a different altitude. The
standards are not just an interpretive device, however. NMR
spectrometers must actually be calibrated to the standard each time a
new element is scanned. "You put the standard sample in and set
‘sea level’ to its spike," Winn explains. There is a different
NMR standard for each element. The NMR standard for mercury compounds is
Environmental Health and Safety’s Michael
Blayney calls for chemical safety advice to be based on empirical
Dimethylmercury couldn’t be that toxic, chemists
insisted. There would have been more cases.
"Dimethylmercury happens to have all the characteristics that
make it a great standard," Kent Sugden says. "It is a liquid,
so it can be used in pure form. There are no shifts in the calibration
signal due to problems associated with solutions, such as changes in the
concentration or pH. The line is consistent every time. This is by
definition what a standard should be."
"Dimethylmercury is a wonderful little compound, if not for its
toxicity," says Winn.
For years dimethylmercury’s value appeared to outweigh its dangers.
"Dimethylmercury didn’t seem to have a history associated with
it," says Russell Hughes, who has used the compound as a reagent.
"People have been dealing with it for more than a hundred
years." The only two previous recorded accidents with
dimethylmercury had happened under very different circumstances from
Wetterhahn’s tiny spill. In 1865 the two English chemists who first
synthesized the compound ended up dying from unprotected exposure to the
fumes. ("You can generate something that’s very toxic without
knowing that it is," Sugden explains.) In the early 1970s a Czech
chemist died while synthesizing a large amount of dimethylmercury. But
the hundred or so labs worldwide that use dimethylmercury have done so
without incident. "Many chemists outside Dartmouth have said to me,
‘I had no idea dimethylmercury was that toxic. It can’t be. Surely
there would have been more cases,’" says Hughes. The general
consensus seemed to be that the compound required care but was
manageable. "Dimethylmercury is a commercial product," notes
Karen Wetterhahn had only recently become interested in
mercury. While on sabbatical she began a collaboration with MIT graduate
student Jonathan Wilker and her own former doctoral advisor Stephen
Lippard. They were using NMR to study the active sites of proteins—the
part of a protein where, as John Bushweller describes it, "the
chemistry goes on." When the sabbatical was over Wetterhahn
continued the research at Dartmouth. She and Wilker were planning to run
their experiments on the NMR spectrometers in Burke Laboratory. The
first step was to prepare a standard. Wetterhahn wanted to have it ready
by the time Wilker came up from Cambridge. Kent Sugden offered to help.
But neither Sugden nor Wetterhahn was eager to work with
dimethylmercury. They discussed the toxicity warnings on the material
safety data sheets: dimethylmercury produced toxic fumes, it was readily
absorbable through the skin, and even small doses could be lethal.
"We agreed it wasn’t a good thing to use," Sugden says. They
opted for a safer, alternative standard—a solution made of mercury
chloride salts. Like all forms of mercury, mercury chloride is toxic.
But it is less volatile than dimethylmercury and doesn’t absorb so
readily through skin. Avoiding mercury chloride’s main danger is
relatively easy. "Don’t eat it," Sugden says. Getting the
mercury chloride standard to match dimethylmercury’s accuracy would be
tricky, however, since solutions necessarily involve extra factors—the
pH of the solution, the amount of mercury chloride. But Wetterhahn and
Sugden chose safety over risk.
They ran the mercury chloride NMR, found the peak, and calibrated the
NMR spectrometer to the standard. They tested the first sample, a
protein with mercury bound to it, then various other mercury compounds.
The results troubled Wetterhahn. "She mentioned to me that the
measurements weren’t what she thought they would be," Sugden
recalls. There were two possible explanations. Either the mercury had
not bound to the protein in quite the way Wetterhahn thought it would,
or the mercury chloride standard was inaccurate. Wetterhahn’s next
step, says Sugden, was to check the standard. "She decided to use
The dimethylmercury arrived in a cardboard box packed with
vermiculite. Inside an airtight metal canister also filled with
vermiculite was a bubble-wrapped bag. Inside of that was the sealed
glass vial. Sugden placed the entire package in a fume hood. The
material safety data sheets stuck in his mind. Dimethylmercury’s low
lethal-dose levels made him nervous. He bowed out. "Karen
wouldn’t make you do anything you’re uncomfortable with," he
Wetterhahn continued. She made time on August 14 to transfer the
dimethylmercury to the NMR tube. She never mentioned to her colleagues
that she had spilled a minuscule amount. Over the next few days she and
Wilker ran the dimethylmercury standard and tested their research
The dimethylmercury standard assured Wetterhahn of reliable results.
It also revealed that the alternative standard had been accurate.
"This is the irony," says Sugden. "The mercury chloride
turned out to be dead on—or close enough that it didn’t matter. But
we didn’t know that until she ran the real standard."
Post-accident tests showed that pairing
SilverShield and neoprene gloves is the only guard against
Karen Wetterhahn seemed born to be a scientist. The daughter of
a chemist, she gravitated early to math and science, earned degrees in
chemistry and math at St. Lawrence University, and completed her
doctorate in inorganic chemistry and physical biochemistry at Columbia
University in 1975. The following year she became the first woman
professor in Dartmouth’s chemistry department. Her innovative ideas in
the new field of chromium carcinogenesis quickly established her as a
key player both at Dartmouth and beyond. "Only ten to 20 people
internationally would have her chromium credentials," John
Bushweller says. According to Sugden, "Karen was one of the
best—if not the best—in metal toxicology. She was the best in
"Karen established one of the major paradigms in chromium
toxicology," explains Brooke Martin, a doctoral student who moved
from Australia to study with her. Wetterhahn established that the
process by which chromium damages DNA—possibly inducing cancer—has
two stages rather than one: entry into the cell and reduction inside the
cell. Cells readily take up chromium in its "+6" oxidation
state. Once the chromium gets into the cell, the cell reduces the metal
to lower—and toxic—oxidation states. Wetterhahn’s work suggested
that DNA damage occurs during this reduction of chromium in the cell.
"She was one of the first people to appreciate the importance of
the oxidation state in the metabolism and toxicity of chromium,"
Martin says. "Her early role is somewhat analogous to that of
Watson and Crick in their ‘discovery’ of DNA’s double helix
structure. All the work was already there to see but no one had really
put it all together in a way that seemed to fit. The simplicity and
utility of some models makes them an enduring reference point for
further research." Wetterhahn’s ideas became known as the
Wetterhahn seemed delighted that the model identified the science
rather than the scientist. "Karen didn’t push herself
forward," Martin says. "She took it as a compliment when a
later generation of her model was taken directly from one of her papers
and used as the illustration on a book cover without acknowledgment or
copyright considerations. She brought it in to show us all as soon as
she got it. Most people would have been affronted, but Karen was
laughing. She thought it was very funny."
By all accounts, Wetterhahn always focused on furthering science
rather than her ego. In a field where egos loom notoriously large, that
in itself was remarkable, say her colleagues. Even more remarkable was
what her lack of ego allowed her to accomplish. She used herself as a
catalyst to bring researchers together. She built collaborations the
same way she built research models—by assembling pieces of the same
puzzle. "Karen’s real gift was being open to a lot of different
ways of looking at the same problem. She was able to use all resources
available to her," says Martin.
Wetterhahn’s chromium group grew to 15 researchers ranging, as
group member Sugden puts it, "from the very biological to the very
chemical." Wetterhahn instituted weekly meetings so members of the
group could report on their projects. "She was trying to train us
to present our work," Martin says. "She would critique the
presentation. But toward the end we’d talk about the science—the
ideas and the experiments. Karen would correlate the different findings.
‘This is so neat!’ she would say. Then she would tell us how that
finding fit in with someone else’s work."
NMR spectroscopy measures compounds against a
standard. For mercury compounds the standard is dimethylmercury.
Chemists and biochemists routinely face hazards.
The work means making peace with risk.
Wetterhahn used her talent for mentorship and her sheer enthusiasm
for science to address a growing problem in the sciences in the late
1980s. Between 1984 and 1989 at least 60 percent of the women who entered Dartmouth intending to
major in science dropped out of the field. The attrition rate for men
during this period was 44 percent. A 1991 National Research Council
conference on how to retain women in science and engineering recommended
providing early hands-on research experiences; faculty, student, and
professional mentors; and financial aid packages that enable students to
spend time on lab work. Latching onto these ideas, Wetterhahn joined
with then-assistant dean of engineering Carol Muller ’77 to establish
Dartmouth’s Women in Science Project (WISP). "She wanted to
captivate students at their highest level of interest—during their
first year—and get them into labs," recounts Mary Pavone,
WISP’s current director. "Some faculty were skeptical that
first-year students could be involved in any significant way in research
projects. Karen built her coalition on her own terms, starting with the
people who knew and respected her. She was willing to believe it was
worth the time, that working with first-year students at the height of
their enthusiasm was an investment in the future." Wetterhahn’s
determination paid off. WISP caught on. Since 1991 more than 175 faculty
and researchers have participated as sponsors for 514 interns. The
number of women majoring in science has risen from 13 to 25 percent of
each class, and WISP has become a national model.
Wetterhahn was tapped to become associate dean for the
sciences and later acting dean of the faculty. Once again she built
collaborations, this time reorganizing the life sciences to stress
interdisciplinary connections rather than traditional boundaries. She
fostered links between biology, chemistry, environmental studies,
engineering, and the medical school. "The life sciences are
interdisciplinary," Wetterhahn insisted. Once again she led by
example. "She played the key role in bringing structural
biology—which utilizes the power of chemistry to understand
biologically important molecules—to Dartmouth," John Bushweller
says. And she spearheaded a new major in biophysical chemistry.
"She was the cornerstone of the biophysical chemistry
curriculum," chemistry professor Jane Lipson says.
Wetterhahn’s biggest collaborative coup came in 1995, when she
secured a $7 million grant from the National Institute of Environmental
Health Sciences’ Superfund research and education program to study how
heavy metal contaminants harm human health. The grant funded five
related studies spanning toxicology, biochemistry, epidemiology, and the
biology of lake ecosystems. The funding was the largest in Dartmouth
history. In a world in which scientists tend to be judged by the size of
their grants, project director Wetterhahn characteristically focused on
the collaborations the money made possible rather than any glory the
grant implied. "We have a lot of expertise here at Dartmouth in
toxic metals. I got people together," is how she put it at the
time. Calling the grant "a microcosm of the life-science
issue," Wetterhahn said, "I like it as a model for how we can
bring together people from different departments and schools. It’s
intellectually coherent, but faculty and students from different areas
are coming together. So many of the large complex problems we face must
be solved by the interdisciplinary approach." She herself was
willing to become as interdisciplinary as necessary. "If I have to
learn biophysical kinetics, whatever I need to understand the problem,
I’ll do it," she said.
Meanwhile Wetterhahn took on the position of acting dean of the
faculty. There was talk that she might become dean. Her presence was
growing beyond campus as well. "The Superfund grant had launched
Karen into a new realm," explains Brooke Martin.
Dimethylmercury changed everything.
When planning labwork for students lab
coordinator Sally Hair tries to anticipate all things that can go
A stroll through Burke Laboratory or the research buildings of
Dartmouth Medical School is all it takes to see the hazards chemists and
biochemists routinely face. Door after door bears signs cautioning that
poisons, carcinogens, radioactive substances, and other dangers reside
inside. Working in such an environment means making peace with risk.
"The only way to cope with worries is the law of
probability," says Jane Lipson. "If events are very low
probability, you can put them out of your mind." But Wetterhahn’s
accident showed the shortcomings of that strategy. "What happened
to Karen was unbelievably low probability," Lipson says. "She
wasn’t stupid and she wasn’t negligent. Most things in life are a
lot more forgiving. This was so phenomenally unforgiving."
"You tend to get complacent about the hazards you work with on a
daily basis," admits Kent Sugden. "An accident drives home
that on a daily basis you have to be aware and take optimum
"The accident was a wake-up call," says Ed Dudek, one of
the post-doctoral fellows in Wetterhahn’s chromium group.
"We’re now extremely aware of everything we’re doing. Everyone
examined his own way of doing the work."
Chemistry has actually never been safer. "The risk of doing
chemistry is less than the risk of driving a car on the highway,"
says Russell Hughes. But safety has traveled a long road. "In the
early days of chemistry people had no idea of the consequences. They
used to describe the odor and taste of compounds," says David Lemal.
Like other senior members of the chemistry department, Lemal has seen
safety consciousness change radically during his career. "When I
was in grad school, we thought benzene smelled nice. We never wore
gloves," Lemal says. Dean Wilcox says that as recently as the
1970s, when he and Karen Wetterhahn were trained, "people were more
cavalier about safety. There was a kind of macho attitude toward lab
work. Safety wasn’t so much an issue."
Over the last decade, OSHA, the federal Occupational Safety and
Health Administration, has made laboratory safety very much an issue.
OSHA required labs to develop chemical hygiene plans, safety instruction
manuals and sessions, and place safety monitors in labs. It has fined
companies and institutions for safety violations. But scientists—from
OSHA and from labs worldwide—are still writing the safety book.
"There is no general body of knowledge about what scientists are
taught about safety," says Dartmouth’s Michael Blayney, who has
been upgrading safety campus-wide since arriving in 1995 from the
National Institutes of Health. Yet even as greater knowledge reduces
risk, safety literally remains in the hands of each researcher.
"The ultimate locus of control is the individual. The ultimate
responsibility for safety comes down to the individual," says
Even the main source of chemical information—material safety data
sheets—has flaws. As Wetterhahn tragically discovered, sometimes data
sheets reflect the limits, rather than the extent, of knowledge. Many
contain inaccuracies or deficiencies, says Blayney, author of a recent
assessment of data sheets. There is a problem with balance as well.
"The MSDS are all starting to sound scary," Dean Wilcox says.
"Even sodium chloride—table salt—sounds dire. True hazards like
dimethylmercury should jump off the page and shout for attention."
The lack of balance is prompting a potentially dangerous backlash in
which scientists downplay warnings—or discount them altogether.
"The material safety data sheets sound hyperbolic. If you took
everything literally you’d be frozen. You wouldn’t get anything
done," says Jane Lipson. "You have to find the balance between
being confident and wary—without crippling yourself."
Scientists do not always find the same point of balance. People have
their own levels of comfort. "If you’re terrified of a substance,
you’re going to make mistakes," says John Bushweller. Although he
routinely works with oncoproteins, the substances that cause cells to
carcinogenically divide, he draws the line at working with the heavy
metals that were Karen Wetterhahn’s focus. "To work with heavy
metals, you have to be careful all the time," he says. "I
don’t think I have the discipline to be safe all the time."
Russell Hughes says he has refused to work with some highly toxic and
highly volatile chemicals. Jane Lipson knows where she draws the line:
"I would never work with dimethylmercury or let anyone work with
Kent Sugden and fellow researchers are
forwarding the chromium work Wetterhahn started.
Wherever they draw the line, chemists rely on prudent lab practice.
"If we have a choice, we try to work with things that are safer.
Sometimes we have to use the more dangerous. We take precautions but
still do it," says David Lemal. Precautions, however, involve
interpretation. Dean Wilcox suggests that Wetterhahn’s busy schedule
may have influenced her approach to the dimethylmercury transfers.
"She handled it in the most efficient way, but not the safest," he says. He suggests that a special piece of
equipment called a vacuum line might have reduced the risk
involved—although he acknowledges that it would not have reduced the
risk of exposure inherent in merely opening the sealed vial, a risk
Wetterhahn thought she had covered by wearing latex gloves. According to
John Winn, specialized equipment tends to be tied to the frequency of a
procedure. "If you are using a toxic substance a lot, you build a
container to do it in," he explains. "If you don’t use it
everyday, you do it with prudent practice, not specialized
"If there’s no uncertainty in what you’re
doing," says Jane Lipson, "you’re not doing research."
But given the scope of chemistry, neither equipment nor prudent
practice provides a complete guarantee. "When you use a thousand
different chemicals in a year, you’re never going to have complete
protection," says Kent Sugden. "You would never do any science
if you spend all your time working out what your protective gear should
"In research you’re always making new compounds," says
Lemal. "You have to assume that new things are dangerous. Treat
everything as if it is dangerous. Don’t breathe it, don’t get it on
you. Nearly all the time that works."
"Once in a while," says Michael Blayney, "you get to
the trembling edge of science and something bad happens."
Risk can never be completely eliminated, either from research
or the chemistry classroom. As Lipson puts it, "If you have no
uncertainty in what you’re doing you’re not doing research." In
chemistry classrooms the goal is to reduce risk to the level that
students can handle. "If students follow the precautions they’ll
be fine," Lipson says. Before they start lab work students are
required to read and sign safety information in their lab manuals.
Safety information is also included in each week’s lab lectures. Sally
Hair, senior lecturer and coordinator for the general and organic
instructional laboratories, puts students through a safety scavenger
hunt to make them aware of where equipment is located. The foundation of
all chemistry laboratories, however, is a well-thought-out plan for what
students can do safely. "I have to put myself in the student
position and try to figure out everything that can go wrong," Hair
says. "Anything that’s of pedagogical value has to also be OK in
terms of safety. I try to avoid things that are really dangerous or
toxic. And I emphasize safety." Students learn the basic rules: no
eating in the lab; don’t store food or drink in the lab refrigerator;
do not eat ice from the lab ice machines; always wear eye-safety
goggles; if gloves get holes, take them off right away; do not wear
sandals; clothing must cover the knees; wash hands before leaving the
lab. According to Hair, a handful of accidents—cuts from broken glass
or minor burns from acids or hot plates—happen most terms. Visits to
general chemistry labs and organic labs revealed that students appeared
relaxed but intent on what they were doing. Only one sign—gloves—
indicated that Wetterhahn’s accident was on anyone’s mind.
"Most students wear gloves most of the time now, even when they
don’t need to," reports Hair. "We’re spending a lot on
gloves. We’re going through hundreds of pairs per week."
In the months since the accident Wetterhahn’s
colleagues, like her husband Leon Webb, 15-year-old son Leon Jr., and
13-year-old daughter Charlotte, have faced both emptiness and regret. Kent
Sugden, who backed away from using dimethylmercury, talks of survivor guilt.
"Perhaps if I’d done it in the beginning this wouldn’t have happened. I
might have been able to get away with it," he says, even while
acknowledging, " that’s what it would have been—getting away with
"I wish I had given my standard talk on permeation," says
Blayney, even though he knows that dimethylmercury would not have
entered the discussion.
"I wish she had talked to me," says John Bushweller.
"I would have shown her a computational trick used by the
biological NMR community to calculate the chemical shifts pretty
closely." This, even though he knows that "pretty
closely" might not have been close enough for Wetterhahn.
"I wish she had told us what she was planning to do," says
Ed Dudek. "We might have tried to talk her out of it. Or if we had
known she was doing the work we might have asked how it went. She might
have said, ‘I had a little spill.’ We would have said, ‘You should
talk to someone.’"
Michael Blayney keeps Karen Wetterhahn’s photo
on his desk to remind him that she was a person, not a statistic.
Karen Wetterhahn died June 8, 1997. At her funeral people spoke of
irony, of how the dangers of heavy metals first claimed her interest and
then claimed her life.
Kent Sugden, who continues to work with heavy metals, sees the loss
in a starker light. "There’s no irony in it," he says.
"Only lion tamers get eaten by lions. It’s the people who work
with toxins who get exposed."
Karen Endicott is senior editor of this magazine.
DARTMOUTH ALUMNI MAGAZINE - APRIL 1998