A single drop of toxic metal comparable to the size of a raindrop landed on a teacher’s skin and led to her agonizing death 10 months later.

Karen Wetterhahn had been working as a research chemist at Dartmouth College in New Hampshire in 1996 where she was closely studying the impact of living organisms when they come into contact with heavy metals.

However, little did she know that she would become a subject of the experiment herself when a droplet of the chemical known as dimethylmercury fell off the tip of a pipette and landed on her latex glove.

Wetterhahn removed the gloves and put on a new pair but it was too late as the chemical had already seeped into her skin and made its way into her bloodstream.

However, the researcher had no idea she had been impacted until she started to notice symptoms including balance, speech and vision issues.

After being admitted to hospital, doctors ran tests and found that Wetterhahn was suffering from severe mercury poisoning, with her levels being a whopping 4,000 times over the recommended amount.

According to reports, Dr Ben Miles detailed just how dangerous it was, explaining: “Not immediately, but so inevitably that doctors can only watch as your brain slowly disintegrates. This is the horrifying reality of dimethylmercury... Once inside the body, dimethylmercury decomposes, releasing mercury ions that bind aggressively to sulphur atoms…

“Which are in particularly high abundance within the neurons of the brain and central nervous system. Robbed of the sulphur that they need, those neurones begin to malfunction and die.”

Despite attempts by medics to save her life, the damage was already done and just 10 months after first being exposed to the chemical, Wetterhahn fell into a coma and eventually her life support was switched off.

After the tragedy, the woman was commemorated by the National Institute of Environmental Health Sciences, who created an award in her honor.

There have also been serious changes to safety precautions in labs using the chemical as people are now aware of how quickly dimethylmercury can seep through protective materials.

In a report published by the Occupational Safety and Health Administration under the US Department of Labor in 1998, it said: “The gloves used in this incident were disposable latex examination gloves, and subsequent permeation testing of the gloves by a certified, independent testing laboratory indicated that the chemical permeates latex, PVC, and neoprene almost instantaneously.”