Cancers,
Tumors, in particular, Gliomas
Dry Eye,
Muscle problems
Damage to the brain – depending upon how many cell phone companies are using a particular cell phone tower. ITAS claims that the more number of cellphone companies sharing a single tower, the greater the hazards of cell phone towers.

Specific Absorption Rate

The specific absorption rate – or SAR as it is known – refers to the rate of electromagnetic energy that is absorbed by the human body when using cell phones and other devices emitting radio waves. It is measured in Watts per Kg of human tissue. If the SAR limit of cell phones is 1.6W/Kg (as in the US), the total time that a person can use cellphones is maximum 6 minutes. Given an error margin of 3, the total time a person can use cellphones translates to only 20 minutes per day.

While some countries have now made it mandatory to display the SAR value of cell phones on their handsets, others have not yet woken up to the dangers of using cellphones. Wikipedia has some more information on SAR including the equation to calculate SAR.