Yale Paper Finds Arsenic Supply At Highest Risk

To demonstrate the methodology, Graedel's team created a fictional solar cell manufacturing firm. Arsenic was at the highest risk of supply disruption over the long-term of the six metals because there is scant interest in mining a poisonous material, with selenium and gold almost as high a risk. Gold occurs at such low concentrations in the ore that mining and processing has the potential to cause significant amounts of air and water pollution, so it has the most severe environmental implications ranking.
http://www.sciencecodex.com/yale_paper_finds_arsenic_supply_at_highest_risk-86195