Rising damp is bad news and might put off potential housebuyers, but a bit of soggy wallpaper is never going to kill you. Try telling that to Napoleon. The French emperor’s death on the island of St Helena in 1821 was always thought to be from stomach cancer, but recent research suggests a more sinister cause. When tests on a lock of his hair revealed high concentrations of arsenic, suspicion turned to the arsenic-based green pigment on his walls, which could have seeped the poisonous gas arsine, thus hastening his demise.

In its most common form, arsenic trioxide is virtually odourless, colourless and leaves little trace of its deadly presence. It was the poison of choice for Victorian murderers - and suicides. The romantic notion of the tortured genius was epitomised by Henry Wallis’s 1856 depiction (above) of the death of Thomas Chatterton. Chatterton, a boy-wonder poet, killed himself with arsenic at the age of 17. The model for the painting, George Meredith, committed marital suicide by accepting Wallis’s offer of work; soon after its completion the artist ran off with Meredith’s wife.

Until the Arsenic Act of 1851 restricted its sale, the poison was readily available. Mary Ann Cotton, the notorious 19th-century murderer, despatched four husbands and at least eight of her children with a dose; later, disguised in a glass of elderberry wine, it did away with half the cast of the 1944 film comedy Arsenic and Old Lace.

But since it was first isolated by the scholar Albertus Magnus in 1250, arsenic has had a vital, as well as fatal, history. Until penicillin was discovered, it was a common cure for syphilis and has recently been used as a chemotherapy treatment for certain types of leukaemia. Homeopaths, who routinely use toxins in minute doses to treat ailments, find arsenicum a useful antidote to a range of maladies, and villagers in the Austrian Alps have used it as a tonic for centuries and built up a high tolerance to its toxic effects.

We all have around 10 milligrams of arsenic in our bodies, and it is the 52nd most abundant element on Earth. Some shellfish, especially prawns, accumulate it as they filter seawater, although you would have to eat about 12kg of them to make you ill. Tragically, its prevalence in the Earth’s crust has provoked perhaps the greatest mass poisoning of the modern world. In Bangladesh, as part of a huge aid programme to eradicate waterborne diseases, wells were sunk straight into the arsenic-tainted ground, killing thousands and putting around half the country’s 125 million people at risk.

But nature may have a cure. Scientists in Florida noticed the Chinese brake fern (or ladder brake), pterris vittata, thriving on an arsenic contaminated site, and discovered its leaves carried 200 times the concentration of arsenic than the surrounding land. They have suggested planting reservoirs in Bangladesh with the sun-loving fern to purify the water supply. If only Napoleon had kept one in his room.

Harvey McGavin