Hmm, I'd never thought about this before, but the obvious connection is with Paris Green, or an earlier similar compound, Scheele's Green

These days it's possible to simply buy a bunch of paints in different colors from an art store, and though some are listed as "permanent" and some "impermanent", most of them can be mixed with others and used in a painting. And in several years, kept from full sunlight, they'd likely be pretty much the same shade they were when you painted, which is plenty of time for you to decide that you don't like the painting anymore. This was certainly not the case for the Old Masters. Their colors were more limited, and the chemical compounds in them could be quite reactive. Say you've painted some streaks of white ( lead white) onto a brilliant yellow ( orpiment) sunset,...Orpiment is arsenic trisulphide, lead white is lead carbonate. The lead changes from lead carbonate to lead sulphide, and your white streaks are now black or brown. But, in say, 1680, there's no way yet you could know the chemstry: you only know ( probably from apprenticing to an artist) what pigments orpiment can't touch or be mixed with.

One lack they had was for a decent, strong permanent green. Verdigris, or copper carbonate ( that green gunk that forms on brass belt buckles) was a nice color but, like orpiment, very reactive and so the color didn't last. In 1755 a German chemist, Carl Wilhelm Scheele, discovered he could make a much more stable copper green if he combined it with arsenic. He didn't know precisely what was going on ( this is still before a lot of chemistry was known) and it seems he got a number of different compounds, but a lot of it was copper arsenite. Later, in 1810, the color and stability was improved again with the addition of copper acetate, and the result became Emerald Green or Paris Green. Nicely transparent, it not only worked as a paint pigment but as a dye as well. It got used for dyeing clothes, even coloring food. Most famously, it got put into the ink for printing a lot of wallpaper in the 19th c. . William Morris, especially, loved the shade. But some people began to get sick- especially children. It turned out that the arsenic was slowly being released, from wallpaper, from clothes. Bigger adults could sometimes handle it, but smaller adults, children and old people often couldn't.. After some resistance ( Morris really did like the color and always seemed to have had his doubts about it being poisonous) it ceased to be used in such a profligate way...but Paris Green did continue to be available well into the 20th c., having a more openly poisonous use as an insecticide, or a way to kill rats and mice, or the murder method in countless British mysteries..

Cobalt Green and Chrome Green were introduced in the late 19th c. Toxic but not nearly as murderous.

George Terry: Pigments, Paints and Painting ( 1893)

EDIT: someone commented that this was too lightly sourced. But it's an oft-told tale, the murderous wallpaper. As a search will show, somebody writes it up as a magazine article every couple of years. It's very appropriate that the Paris Review would do one and have the best pictures.

The link to the 1893 artist's manual I thought useful- it shows a time in which newer, safer colors were beginning to drive out the riskier ones, but you could also read about it in newer manuals, like Ralph Mayer's great Artists Handbook, which has been through many, many editions.

I did a brief search, but the story of the unmasking of the dangers of Paris Green does not seem to have rated an entire book, though there are relevant chapters . The profligate use of the stuff as an insecticide, also, seems to be just another sad simplicity- years after it stopped being employed in wallpaper it was being sprayed over the landscape..