Over time, she began to feel very dizzy, lost her balance, was disoriented, and felt faint. She didn’t worry much, and blamed it on work-related fatigue and stress.
Time didn’t improve the situation, on the contrary. The symptoms worsened in frequency and intensity, and mental confusion was added, as well as intense tinnitus that never went away, and her field of vision gradually narrowed until it seemed like she was seeing through a couple of toilet paper tubes. Karen understood that something serious was going on.
The woman’s situation looked a lot like mercury poisoning, a substance she frequently works with, but there was a problem that ruled out this possibility. Karen was known for her methodical approach to adopting all safety measures: gloves, gown, mask, fume hood, etc. She has never had direct contact with mercury, nor has there ever been an accident; the worst thing that has happened, and in any case months before, is the accidental dripping of some drops of mercury on the latex gloves, which she immediately removed, and then, out of caution, washed her hands that were already clean. Something totally negligible, therefore.
Karen gets worse and worse, until the only possibility left to explain her situation is precisely mercury poisoning; the tests confirm that her values are 20 times higher than the maximum limit found in a healthy person. The value is so high that at this point a murder attempt is hypothesized; in fact, mercury, although very toxic, is slowly eliminated from the body. To have such a high value, Karen must be continuing to take it in some way. So the woman is constantly monitored to understand who is poisoning her, but despite the close surveillance and all the therapies available at the time to chelate the mercury, which at first seem very effective, she continues to get worse.
The solution to the mystery comes in one of the woman’s last moments of lucidity: she remembers that in addition to mercury, she has actually worked with dimethylmercury. The latter is one of the most toxic substances known to humans, to be treated with the utmost caution, because it is unforgiving: very small quantities are lethal. It is said that even smelling it, sweetish, is already a certain death sentence. Karen, as usual, when she worked with dimethylmercury used all the protective devices, but there is one thing she was unaware of and for which she paid dearly: the substance is able to penetrate latex gloves. The droplets from months before were dimethylmercury and not mercury, and they managed to be absorbed by the skin before the woman was able to wash her hands. From there they entered the blood and started doing everything that neurotoxins do.
Dimethylmercury is much more difficult to eliminate than mercury and is also highly lipophilic, meaning it binds to fats. The human brain is 60% fat. The substance circulating in Karen’s body gradually accumulated in her nervous system, damaging it progressively, irreparably and unstoppably. Karen went into a coma, and her husband remembers seeing her cry; those tears, unfortunately or fortunately, were only a physiological event, because the doctors estimated that at that point Karen was no longer able to feel pain or conscious sensations.
About a year after the drip incident, Karen was taken off life support, becoming the third person known to have died from dimethylmercury poisoning at that time.