Here’s an article about the nouveau vert of the 1860s, or a new synthetic green dye: On that deadly emerald green: How emerald green became fashionable, despite its poisonous past. 

Before 1859, green pigments came from arsenic mixed with copper, which, uh, killed you:

The “green tarlatan so much of late in vogue for ball dresses” contained as much as half the gown’s weight in arsenic – as one article explained. [Alison] Matthews David concurs with this assessment, adding that “a ball gown fashioned from up to 20 meters of this fabric would have 900 grains of arsenic. It was possible that no less than 60 grains could fall from the dancing gown in the course of a single evening. For an average adult, four to five grains were already considered lethal.”

(Arsenic wasn’t used in just fabric, either. William Morris, Mr. Arts and Crafts, owned a copper mine and used copper arsenite pigments in his wallpapers. He also dismissed claims of that green being poisonous up through the 1880s.)