Tea in a thermos cup will soak heavy metals? Don't pour these four drinks inside! The Nanjing Food and Drug Supervision and Inspection Institute tested the vacuum flask (stainless steel liner). The inspectors brewed the same type of tea in glass cups and vacuum flasks according to people’s daily tea making methods. Refer to the national standard GB5009.268-2016. The National Food Safety Standard "Determination of Multi-Elements in Food" specifies the method to detect the content of lead, arsenic, chromium, and cadmium in two kinds of tea.