Sometime in 2012 the world will hit 4.5 billion cell phone users. That's 4.5 billion people who take an electromagnetic device and press it almost every day against their cranium without ever thinking that it might possibly have a dangerous effect on their brain, ears, mouth and other structures in close proximity. The cell phone industry has grown so fast that issues of health and safety have never crossed anyone's mind.
That is until recently...
In the last decade one study after another has come out showing just how toxic cell phones are to humans. Is it any wonder? Humans are, after all, primarily a vast electrochemical neuronetwork and a phone seems almost diabolically designed to interfere with our "wiring."
The argument from the industry is that the output from a cell phone is simply not enough to damage DNA and, therefore, cell phones must be safe. That is a debatable theory as it turns out, but, regardless, there is much, much more to us than just DNA. Cell phones affect us in many nasty ways that have nothing directly to do with DNA damage.
Think pesticides are bad? Cell phones may be even more deadly. Read below and I'll give you non-DNA 15 reasons to take that silly device in your pocket and drop it into the nearest fishtank:
1. Upregulation of Genes. An animal study showed clearly that exposure to cell phone radiation upregulated genes.  So, while experts wrangle over whether cell phone radiation can alter DNA, it is somewhat a moot point: cell phones can clearly affect genetic material through upregulation anyway. The cells affected were neurons by the way.
2. Free Radical Damage and Fertility. Recent studies have shown that cell phone radiation can alter DNA throught a surprising pathway: increasing oxidative (free radical) load within cells, a huge health danger it goes without saying.  We all know that antioxidants are, in general, a good thing and help protect health. The study above showed that cell phones accelerate the opposite phenomenon and actually damage the DNA within sperm and decrease male fertility.
It does this within the mitochondria of sperm cells and this leads to a frightening question: "Does cell phone exposure accelerate mitochondrial damage in other cells as well?" If so, this would be downright dangerous. Mitochondria are so important to health that there is an entire theory of aging built around these cell structures. Anything that negatively affects them will lead to health issues.
3. Testosterone. Strangely enough, a study showed that cell phone exposure increased testosterone.  Again, this may seem like a good thing, but can anything that is frying your sperm be doing your body good? It may affect testosterone positively, but what other hormones does it affect negatively?
4. Blood Brain Barrier. A number of animal studies have documented that cell phone radiation alters the permeability of the blood brain barrier, i.e. lets more molecules in the blood stream pass into the brain. (See my link on Electrosmog for more details.) This is incredibly dangerous as it could potentially allow toxins, including excitotoxins, to more easily cross the only line of defense that your brain has. This research shows yet another way that cell phone EMF's can affect cell functioning and processes. Childhood leukemia and brain cancer have been on the rise.  Could this be contributing?
5. Brain Glucose Metabolism. One study looked at PET scans of the brain before and after cell phone usage. What they found was scary indeed: after just 50 minutes of cell phone usage, the areas of the brain around the ear had altered glucose metabolism.  Again, this demonstrates that cell phones change activity on the cellular level.
NOTE: I also give coverage to the very ugly health issues of "dirty electricity" here in my link on The Dangers of Electrosmog .
6. Brain Tissue Damage. There is some evidence that cell phones may actually damage brain tissue, indicating yet another danger associated with long term usage. 
7. Mouth Cancer (Heavy or Rural Users). Many studies have shown that cell phone usage does not significantly increase cancer risk. However, still other studies have. One disturbing example is a study of rural users. The reason that rural users are of particular concern is that cell phones in this situation emit more radiation to reach more distant towers.
One study found, for example, that cell phone users in these regions were much more likely to get cancer of the salivary gland.  One 2009 meta-analysis explained that, although cancer and cell phone usage has been studied often, there are a number of important issues with almost all of the studies and the study periods have generally not been of sufficient length to come to a definitive conclusion.  Cell phone usage may very well lead to brain cancer over decades, for example.
8. Bone Loss. One recent study found that cell phones - many people carry them in their pocket - lead to increased bone loss in the hip area.  Although the bone density loss did not come close to that of someone with osteoporosis, this is yet another example of cell phone usage affecting tissue on a cellular level.
9. Behavior Problems in Children. Cell phone usage may pose a danger to the brains of our children as well. One study showed that it affected behavior and mood in over 13,000 kids.  The most significant factor was in-the-womb exposure, which has a signficant relationship to childhood emotional problems and hyperactivity. Again, this is another sign that cell phone exposure does in fact affect structures within the brain.
10. Tinnitus. Hearing also appears to be affected according to some studies which show a relationship between cell phone use and ringing in the ears.  Again, it's the tissues that are closest to the cell phone that are affected.
11. Eye Damage. One study showed that electromagnetic radiation similar to cell phones was capable of damaging the eye.  While some recent studies have shown no increased risk of eye cancer from cell phone usuage, this study showed that it is very possible that a "bubbling" could be initiated on the surface of the lens, which fortunately appears to be reversible. Nevertheless, who wants to take a chance?
12. Headache, Fatigue and Sleep. One Saudi study found an association between cell phone use and "headache, sleep disturbance, tension, fatigue and dizziness." The incidence of headache was particularly high. Of course, this is just one study but inicates possibly brain function issues could be associated with cell phone usage. 
13. Erectile Dysfunction. A recent study shows that those with erectile dysfunction were 2.6 times more likely to carry a cell phone in their front pocket.  Ouch! Again, this is scary when coupled with the bone loss study above for the same. (See #8.)
2) Neuroscience Letters, Jan 22 2007, 412(1):34-38, Exposure to cell phone radiation up-regulates apoptosis genes in primary cultures of neurons and astrocytes"
3) PLOS, 2009, "Mobile Phone Radiation Induces Reactive Oxygen Species Production and DNA Damage in Human Spermatozoa In Vitro"
8) Electromagn Biol Med, 2008, 27(2):103-26, "Radiofrequency and extremely low-frequency electromagnetic field effects on the blood-brain barrier"
11) Environ Health Perspect. 2009 March; 117(3): 316 324, "The Controversy about a Possible Relationship between Mobile Phone Use and Cancer"
13) Epidemiology, Jul 2008, 19(4):523-529, "Prenatal and Postnatal Exposure to Cell Phone Use and Behavioral Problems in Children"
14) PLOS ONE, Received: November 23, 2008; Accepted: March 4, 2009; Published: March 27, 2009, 4(3): e5026, "Association of Tinnitus and Electromagnetic Hypersensitivity: Hints for a Shared Pathophysiology"
15) The Open Ophthalmology Journal, 2008, 2:102-106, "Non-Thermal Electromagnetic Radiation Damage to Lens Epithelium"
16) Saudi Med J, 2004 Jun, 25(6):732-6, "Association of mobile phone radiation with fatigue, headache, dizziness, tension and sleep disturbance in Saudi population"