A phone in a desk drawer isn't an environmental threat. The trouble begins when people toss their old handsets in the trash, which invariably wind up in a landfill. It's there that the phones' toxic cocktail of hazardous materials are dangerous.

Green activists have long derided the mobile phone as an . Recycling these devices keeps dangerous materials out of landfills and incinerators. It also reduces greenhouse gas emissions. The EPA estimates that recycling all of the 100 million mobile phones in the U.S. that have reached the end of their lives would save enough energy to power more than 18,500 U.S. households with electricity for one year.

The wireless industry needs to do more to encourage recycling. Outreach programs like the EPA's Plug-In To eCycling are a good start, but greater incentives are needed. Why not pay cash for old phones? Think of it as a Cash for Clunkers program for the handset crowd.

To its credit, Sprint appears serious about boosting the rate of phone recycling. CEO Dan Hesse says his company hopes to recycle 90 percent of wireless devices by 2017.