How much do you like the color green? It's beautiful isn't it, the color of alligators and peas. But if your answer wasn't "I would literally die for it" then you aren't as big a fan as the Victorians, who spent decades getting killed by the color and their own unwillingness to go outside for a while to see it on e.g. trees.
In the mid-1800s, four children in a working class area of London became ill with sore throats and respiratory problems. They were diagnosed with diphtheria, but their physician remained puzzled as to how they picked it up, given that their home showed none of the signs they thought were associated with the disease, and no other local children were infected. The children died of their disease before the real culprit – their parents' taste in wallpaper – could be found.
In 1857 a physician, William Hinds from Birmingham, UK, began to feel overwhelming nausea and abdominal cramps every evening upon returning home. Weirdly, unless you're the type to look at your nice green wallpaper and wonder if it's quietly murdering you, the stomach cramps, urge to vomit and headaches ceased every night when he went to bed.
Hinds eventually realized that he felt ill when he was in his study, with its nice green, murder-y wallpaper. Taking the time to test it, just as public health officials did in the case of the four dead children, he found that the nice green paint contained arsenic, which had been slowly poisoning him whenever he entered his office.
When he removed it, just as a string of others experiencing the same problems did, he found that his health improved significantly.
The culprit was invented back in Sweden in 1775 by Karl Wilhelm Scheele. Named Scheele's Green, the color was made of copper arsenite, and was as popular as it was toxic. According to wallpaper manufacturer estimates there was around "one hundred million square miles of it in Britain alone". The ink flaked off and was inhaled by house occupants, and produced arsenic gases that were inhaled, apart from in one tragic case in 1862 when children licked the wallpaper directly, and died shortly afterwards.
Poisonings, evidence and bodies piled up. A rival green – known as Paris Green or emerald green – didn't help calm deaths, as it too was made with arsenic. Slowly but surely, the medical profession launched a campaign against the color, though they faced opposition from industry and people who believed that they'd be safe if they avoided directly licking the wallpaper.
The public began to stop plastering poison over their walls following the death of Matilda Scheurer in 1861. Scheurer was employed to dust artificial leaves with Scheele green powder. Vivid reports of her dying with the whites of her eyes turned green and "an expression of great anxiety” turned the public against the paint, and it gradually fell out of use, as manufacturers switched to other ingredients amongst the public pressure.
But for a long time, a lot of people died because of their love of a very particular shade of green.