In a tragic end to a story that began last summer, an internationally known research chemist at Dartmouth College in Hanover, New Hampshire, Karen Wetterhahn, 48, died 7 June of poisoning from a few drops of a potent neurotoxin she spilled on her lab glove 10 months ago.
Wetterhahn studied the effects of heavy metals on living organisms. The accident occurred when she was attempting to measure the nuclear magnetic resonance spectrum of dimethyl mercury, which is used as a reference material for other toxic compounds. "She was taking what any of us would have considered prudent and reasonable precautions," says John Winn, head of the Dartmouth chemistry department. She used a hood to protect her from fumes and was wearing a face shield and latex gloves when she spilled the dimethyl mercury, a colorless, highly volatile organic compound 3.2 times as dense as water on her glove. It apparently was absorbed almost immediately.
Wetterhahn reportedly did not regard the incident as serious at the time. But last January she began experiencing difficulty with balance, speech, vision, and hearing. She was hospitalized, and on 28 January was diagnosed with mercury poisoning--with blood levels 80 times the threshold level for toxicity.
Three weeks later she went into a coma. "I don't think any of us recognized" the mercury would turn out to be so penetrating, says Winn--or that it would be so "compatible" with latex. Subsequent tests showed that the mercury "penetrates disposable latex gloves in 15 seconds or less," Winn and two colleagues reported in a letter in the 11 May Chemical & Engineering News. They recommend that with highly toxic chemicals, two pairs of gloves--one of them laminated, the other heavy-duty--be worn.
Chemist Tom Clarkson of the University of Rochester in New York, where Wetterhahn's blood sample was analyzed, says methyl mercury used to be a popular crop fumigant. Its main use currently is to calibrate other compounds. Now, says Winn, "We're trying to urge the chemical community to establish a safer substitute for use as a standard."