Short answers, pulled from the story.
Friedrich Stromeyer isolated a new element in 1817 while examining zinc carbonate samples sold to pharmacies in Germany. Karl Samuel Leberecht Hermann investigated the same discoloration in zinc oxide at the same time and found an impurity he first suspected was arsenic due to a yellow precipitate with hydrogen sulfide.
In air, cadmium burns to form brown amorphous cadmium oxide (CdO) while the crystalline form appears dark red and changes color upon heating. Hydrochloric acid dissolves the metal to create cadmium chloride, sulfuric acid creates cadmium sulfate, and nitric acid produces cadmium nitrate.
By 2006, only seven percent of total consumption went to plating and ten percent to pigments. This drop was compensated by a growing demand for nickel-cadmium batteries which accounted for eighty-one percent of US consumption that same year.
The Jinzū River area in Japan became contaminated with cadmium during mining operations decades before World War II. Cadmium accumulated in rice crops along the riverbanks downstream of the mines where local agricultural communities consumed the grain.
In June 2010, McDonald's voluntarily recalled more than twelve million promotional Shrek Forever After 3D Collectible Drinking Glasses due to paint pigments containing cadmium. Reports of high cadmium levels in children's jewelry led to a US Consumer Product Safety Commission investigation in 2010.