Karen Wetterhahn - Accident

Accident

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.

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; 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, at 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 when 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. 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 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." 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 Czech chemist in Czechoslovakia had suffered the same symptoms as Wetterhahn after synthesizing 6 kg of the compound.