Volunteers are invited to print out the cards with the QR codes and place them on store shelves in front of Hershey products. The cards say: "Hershey's chocolate is tainted with child labor."

The QR code opens a web page at that encourages people to take action in encouraging Hershey to disclose its supply chain down to the farm level and source only from farms that have been verified to not use child labor. The groups behind the campaign say that Hershey won't disclose specifics about its cocoa sources, which are mainly in an area of West Africa known for abusive child labor practices.

The groups involved include Global Exchange, Green America, International Labor Rights Forum and Oasis.

They partnered with Change.org, an organization that helps other organizations run various types of campaigns. Change.org came up with the idea for the QR codes, said Adrienne Fitch-Frankel, the fair trade campaign director with Global Exchange.

She expects that many people will hear about the campaign today and will place the QR code cards in stores this week.