1. On Wireless Safety  National Cancer Institute

This article deals with using phones close to your head, no studies show any conclusive RF issues or correlation.

2. For towers from The American Cancer Society

At ground level near typical cellular base stations, the amount of RF energy is thousands of times less than the limits for safe exposure set by the US Federal Communication Commission (FCC) Is in excess of these limits just by being near a cell phone tower.

3. Do cellular phone towers cause any other health problems?

High levels of RF waves can cause a warming of body tissues, but the energy levels on the ground near a cell phone tower are far below the levels needed to cause this effect. So far, there is no evidence in published scientific reports that cell phone towers cause any other health problems. The antennas emit less than 100 watts power, your light bulbs at home emit nearly this same level, FM radio stations broadcast at 100,000 watts, cell towers a small fraction of that strength.

From the FCC with a PDF at the bottom