Forming an opinion should be your last operation, and not your first. There are constant cries that the telecom industry is only concerned with profits, and doesn't care about its customers. Truer words were never spoken. Their primary goal is to make money. Every tower site goes through a grueling process of leasing, testing, and zoning that is being overseen by attorneys at every step.
Liability is a major concern.
If those companies building towers thought there was any possibility of being sued and loosing money they would discontinue building towers. Look what happened to the tobacco industry. They certainly do not want a repeat of anything like that. If this technology weren't proven to be perfectly safe none of these companies would risk billions of dollars on it. Go spend your energy on something worthwhile, like becoming informed.