– Naturally occurring heavy metal
– ‘Hg’ on the periodic table (atomic no.80)
– Used in car batteries and thermometers
– Low levels not particularly toxic to adults and harmless if touched
– Inhaled vapour attacks the brain and lungs
– The cause of the Iraqi poisoned grain disaster
– Suggested as a possible cause of death of Mozart (used to treat his syphilis)
Mercury is a heavy metal which is commonly used in thermometers, car batteries and as a cure for syphilis. Touching mercury is harmless, however deadly if ingested or inhaled – which is problematic as it starts to turn into a gas at room temperature. Mercury is found in large fish (such as tuna) and can be potentially deadly over time, which is why restricting consumption to 170g per week is recommended.
Symptoms include rashes, muscle weakness, memory loss, numbness and issues with sight, hearing and speech. The later stages result in excessive sweating, rapid heart-rate, hypertension and eventually death.
One of the first Hollywood scandals that was heavily publicised, in 1920, involved American silent film actress, Olive Thomas. She died five days after taking her husband’s syphilis medication, mercury dichloride. While her death was ruled accidental, it became fodder for media speculation.
In late 1971 a mass poisoning began in Iraq lasting until March 1972. Grain treated with fungicide methylmercury, intended for planting and not human consumption, was imported into Iraq from Mexico and the USA. A number of factors, such as the labelling of bags in Spanish and English, or skull and crossbones, which didn’t mean anything to Iraqis and the late distribution to farmers (outside of the growing cycle) meant rural families consumed the grain instead of planting it. The grain had been dyed a pink, but while the dye washed off, the mercury didn’t. Locals experienced skin numbness, lack of coordination of muscle movement and vision loss. The recorded death toll was 459 people, but figures up to ten time higher are suggested.
An organometallic compound of mercury (dimethylmercury) is one of the world’s strongest neurotoxins. Symptoms don’t appear for months after exposure, and it only takes as little as 0.1mL to be lethal. On 14 August 1996, a professor of chemistry, Karen Wetterhahn, spilt a drop of dimethylmercury on her latex-gloved hand. She took necessary precautions, but in April 1997 she began to experience poisoning symptoms (slurred speech and loss of balance). As her symptoms worsened she slipped into a coma and seemed to develop a resistance to pain. The mercury ate at her brain “like termites” according to her doctor. She ended up in a vegetative state and died ten months after exposure.