Well, *that's* an interesting letter

Tucked in the letters to the editor in C&EN, an unusual comment about the death by exposure to dimethylmercury of Dartmouth chemistry professor Karen Wetterhahn: 

I read the article on Karen Wetterhahn with a profound sense of loss and sorrow that has not fully abated after 25 years. I was one of Karen’s graduate students, and I have come to recognize that she trained her other students and me very well.

I’d like to share an anecdote about Karen’s teaching style. Karen cultivated an air of omniscience, which certainly drove her students to prepare well for discussions with her about their research. One of her favorite questions was, “Don’t you know?,” implying that the student had not done their homework. Karen had wide-ranging knowledge, but she also had human limitations. Once, I called Karen’s bluff and confessed that I didn’t know the answer to a question, so I asked her what the answer was. We both chuckled when she admitted that she didn’t know either. Nevertheless, all her students learned the importance of asking insightful questions.

This brings me to a deeply troubling point raised in the article. I don’t agree with the conclusion about how Karen was poisoned. Karen taught me that if you disagree, you better have data on your side, so here goes. The New England Journal of Medicine article estimated that Karen likely absorbed about 1,344 mg of mercury, meaning she likely absorbed 0.44 mL of dimethylmercury. To do so meant she had to have been splashed with more than that—probably closer to 1 mL since some of the compound would be lost to evaporation or remain in the glove. This is a lot more than a drop or two.

When I was in Karen’s lab, I did some experiments using coaxial nuclear magnetic resonance tubes, which allowed a small volume of an external standard between the tubes. I don’t know what Karen was using for an NMR tube, but in currently available technology, where the reference goes into the center of a larger sample tube, typical volumes for the inner reference standard for a 5 mm tube are 60 µL, while the outer sample volume is 10×. If Karen was using less than 0.1 mL of dimethylmercury, how could she have absorbed 10× what she was transferring? (Her lab notebooks might provide insight.) My supposition is that either she was splashed with more dimethylmercury than what was released from the pipette through her glove, or there was another method of ingestion, conceivably involving the deliberate actions of another individual.

Samuel Brauer

Shelton, Connecticut

Editor’s note: An investigation into Karen Wetterhahn’s death concluded, “The rapid, monophasic, first-order increase in the mercury content of hair is consistent with either one or several episodes of exposure to dimethylmercury beginning on or about August 14, 1996, and is consistent with the evidence (reports from coworkers and information from labeled vials and laboratory notebooks) that a single accidental exposure to dimethylmercury occurred on August 14. . . . Our patient’s accidental exposure may have resulted from both transdermal absorption of the liquid (given the lack of protection provided by disposable latex gloves) and inhalation of vapors (even though the work was conducted under a fume hood)” (N. Engl. J. Med. 1998, DOI: 10.1056/NEJM199806043382305). Wetterhahn did not record in her lab notebook the quantities she used or planned to use, according to John Winn, a Dartmouth professor emeritus of chemistry, who was chair of the department when Wetterhahn died.

I'm not an analytical chemist, so I can't pretend to have an educated opinion about who is right or who is wrong, but it seems that there are more possible explanations other than deliberate poisoning...

(Read all the letters for lots of articles about dimethylmercury in the good old days...)