The International Association of Antarctic Tour Operators recommends that boot-washing stations use a solution of water and a broad spectrum disinfectant such as Virkon S. Virkon S's manufacturer, Lanxess, markets Virkon S as a "biosecurity" product. Lanxess is a German speciality chemicals company, spun off at the start of the 21st century from Bayer AG, the German pharmaceutical company that famously tested its products on incarcerated people in the Dachau, Auschwitz, and Gusen concentration camps. Bayer AG was a subsidiary of IG Farben, the manufacturer of Zyklon B, the gas used in the Nazi death showers.