Baylor, there's a few things that should be considered in your question. BlueMR2 hit some solid points, as did Nords, but have a few other things to chew on given the thought processes. I do think these are things worth bringing to the table to consider.
1) No, there's no conclusive evidence that there's a link between cancer and non-ionizing microwave radiation from GSM/CDMA and WiFi networks. That said, we're still less than a decade into the levels of exposure we're subjecting society to. As for the shaky studies both proving and disproving any adverse health effects with non-ionizing radiation, it's safe to say there's bias and corruption on both ends. Everyone has an agenda to prove, and people with agendas manipulate numbers and throw out datasets that disprove their pre-concluded ideas.
2) Something doesn't have to cause cancer for it to be unhealthy or cause a negative impact on a living organism. Even high enough levels of non ionizing microwave radiation can cause cellular damage through heat and other means. There has been preliminary evidence linked to cellular DNA and structural damage with microwave radiation, even at really low levels. This comes at no surprise however, where there have been MRI studies that have shown that a solid hour of standard cellphone radiation exposure can increase brain tissue temperatures by measurable amounts. Once more, however, we're still far too early in the game to know what sorts of ill effects will be seen with lifetime low level accumulation. The hubris of man is that he always thinks that what he knows right now is the pinnacle of knowledge and scientific discovery. That may be true insofar as it's all mankind knows, but mankind really still doesn't know squat. We're still making regular discoveries that void out conclusions that we thought we'd already etched in stone with health and biology regularly. Clearly, we need more good studies.
3) This radiation can do damage to living organisms, otherwise there wouldn't be SAR limits on devices. The debate becomes "how much" which ties back to the first two points. Fortunately, we're dealing with mostly flea power broadcasting in the greater scheme with handsets, and has been pointed out it doesn't take much distance to massively drop off exposure levels. No, we aren't talking about holding a 1000W microwave oven against your head, but when dealing with unknowns, why not simply err on the simple side of caution instead of being a slave to technology or potentially bad science? It's not difficult.
4) There's the social erosion and psychological impact aspect as well. Being attached to these things perpetually isn't a healthy place to be mentally. It distracts from life, it's addictive, and it reduces your ability to unwind, relax and simply be bored... and boredom is a good thing. Being at the beck and call of a little electronic device is no way to live, no matter how many people have fooled themselves into thinking it is.
There's a reason why I approach my guide the way I do and push for home use with VoIP carriers. We clearly don't know enough from a scientific standpoint yet to be fully in agreement to the risks associated with this sort of technology and constant exposure even at these levels on a regular basis, so I advocate against using the cellphone unless absolutely necessary. This has a two-fold effect: 1) it limits your exposure on the safe side of the argument spectrum, and 2) it saves you massive amounts of money in the process. That's what you'd call a win-win.
As for my lack of citation with the points... normally I cite the living daylights out of posts, but I'm deliberately omitting them this time around to encourage research by all parties.