Charging people's batteries.
D003343:Corrosion; D003723:Dental Amalgam / Q000009:adverse effects; D004570:Electrogalvanism, Intraoral; D006801:Humans; D008452:Maximum Allowable Concentration; D008628:Mercury / Q000009:adverse effects*; D009967:Orthodontic Appliances / Q000009:adverse effects
D003723:Dental Amalgam; D008628:Mercury