Of the 50 million cell phones replaced worldwide each month, only 10 percent of them are recycled, according to the EPA. It's a startling statistic, considering how easy it is to recycle (and the sheer volume of harmful parts in cell phones).

Well, environmental services company e-Cycle is adding one more incentive to recycle old phones. In honor of Earth Day this month, e-Cycle is offering companies the chance to win one of four iPad 2 tablets when you sell or recycle a phone to e-Cycle by May 31.

But wait: isn't this just a gimmick to get guys like me to create awareness for e-Cycle, a company that makes profits off your old devices? Well, yes, of course. But it doesn't really matter to me whether you use e-Cycle or some other company—your odds of winning an iPad 2 are slim, and I'm sure there are a half dozen companies that offer a similar service.

Whichever company you do go with, here are a few reasons you should, without question, recycle or reuse all your old mobile devices:

1. Profit. Depending on the device, e-Cycle will provide a cash back incentive. For old-fashioned "dumb phones" and broken devices, that number will probably be $0 or close to it. However, if you're upgrading a set of company smartphones, odds are you can get a decent check for smartphones that are only 1-3 years old.

2. Security. If you're simply throwing away old cell phones, there's a risk that sensitive information could be mined off that device. e-Cycle makes sure to wipe the device clean and tests that there is no network connection.

3. Corporate Responsibility. Honestly, the best reason to recycle your devices is because it's the ethical thing to do. According to the EPA, one cell phone packs the toxins to contaminate 40,000 gallons of water. We need to responsibly dispose of old technology to protect the environment.

Another option for older devices would be to sell them through Ebay or another channel—just make sure the device is fully wiped so there isn't a security risk. I would suspect you could get more money for modern devices this way, but it adds an extra degree of effort.

Do you recycle your old cell phones? If so, what service do you use? Chime in via the comments section or on Twitter.

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