They're classifying cell phone use as a "Group 2B" carcinogen, which means it's "possibly" carcinogenic. The most famous residents of Group 2B carcinogens are DDT, lead, and nickel.

Pickled veggies from Asia are also included. Beware the kimchi of death.

Source: http://en.wikipedia.org/wiki/List_of_IARC_Group_2B_carcinoge...

EDIT: I also want to add that this is yet another case of mass media distorting a report that is careful to identify a) that there is no causality, just correlation and b) what exactly the classification means. That headline is linkbait bullocks: that report does not conclude that "cell phone use can increase cancer risk." It essentially says, "We're acknowledging that it might. Possibly. Maybe."