Short answers, pulled from the story.
Jöns Jacob Berzelius and Johan Gottlieb Gahn discovered selenium in 1817 while processing pyrite samples from the Falun Mine near Gripsholm, Sweden. They identified the element as a red solid precipitate that emitted an odor resembling horseradish during their chemical experiments.
Berzelius named the new element selenium after Selene, the Greek goddess of the Moon, to reflect its relationship with tellurium which was named for the Earth. This naming convention highlights the periodic table connection between these two similar elements discovered in the early 19th century.
About 2000 tonnes of selenium were produced worldwide in 2011 with major production occurring in Germany, Japan, Belgium, and Russia. China remains the dominant consumer annually consuming between 1500 to 2000 tonnes primarily for metallurgy and glass manufacturing applications.
Selenium functions as a cofactor for reduction of antioxidant enzymes such as glutathione peroxidases found in animals and some plants while both elemental forms and salts can cause selenosis symptoms including diarrhea fatigue hair loss joint pain nail brittleness nausea headache tingling vomiting and fever. The US Recommended Dietary Allowance for teenagers and adults is 55 micrograms daily yet increased dietary intake reduces mercury toxicity effects only at low to modest doses.
Seventeen species of fish were eliminated due to wastewater containing 150 to 200 micrograms of selenium per liter discharged into Belews Lake North Carolina from 1974 to 1986. Selenium poisoning passed from parents to offspring through eggs causing malformed fish fetuses with problems feeding or respiring while organoselenium compounds concentrated over 200,000 times by zooplankton.