Dive summary:

• Health officials are looking for who threw away two Tic-Tac sized pieces of Radium-226 in the Mesa County landfill in Colorado.
• The two pieces were found amongst other waste such as glass plates for X-rays, a chemistry set and books about lasers.
• The pieces emit twice as much radiation in one hour as the safe exposure limit level allows the landfill to take in for the entire year.

From the article:

The piece of metal, no bigger than two Tic Tac mints, was discovered when it set off a radiation alarm as a city trash truck entered the Mesa County Solid Waste Facility on April 24. The material, identified as Radium-226, was found in a piece of folded tape that was believed to have been placed in a PVC pipe labeled "Source." It was mixed in with other trash that included glass plates used for X-rays, a chemistry set and books about lasers.

The bit of radioactive metal was originally set aside in a locked area until officials with the Colorado Department of Public Health and Environment identified it as Radium-226 and determined it would need to be in a shielded container and eventually taken to a radioactive disposal site. ...