Canon LBP7210Cdn Manual page 369

When handling the toner cartridges, hold them properly as shown in the figure. Do not place it
vertically or upside-down.
Do not touch the high-voltage contacts (A).
This may result in damage to the cartridge.
Take out the new toner cartridge from the protective bag.
You can open the protective bag with your hands from the notch.
When opening the protective bag with scissors, be careful not to damage the toner
cartridge.