Look, terrier, they are never going to be so close that they are worse than the output of the phone itself. You hold the phone next to your head, typically about 1cm from the brain. The maximum output of the phone is about 1W in a poor coverage area, about 20mW typically. So if the mast is 15m high, and you are right next to it, it would need to output 45kW to equal the field strength due to the typical handset, and 2.25MW to equal the worst case. The actual power is typically 1kW maximum, and is usually less than this.

Concentrate on the ugly, and the planning rules that let them plonk them almost anywhere without consultation.