I do not know any proven facts about it. My daughter's high school was beside a large power center and when you got out of the car, you could hear the buzzing. Also if it was raining, you could hear them zapping when the rain hit them.
There was some news about some children who lived on the power line route being sick but who knows if it is true or a coincendence. The news media loves to fire people up and instill fear.
Damaging to our health,,, I don't know but think about it..... It is harmful to drive a car, ride a bike, walk across a street, etc but who knows the actual extent.
I would not purchase a home with the lines in sight only because I wouldn't want to look at them daily and even have the remote question in the back of my head if they were dangerous or not. I wouldn't take that chance but my reasoning is solely for asthetics, not health. Around here, they will damage your property value just as a water tank, etc in sight of the home that obstructs a clear view.
Good luck with your decision.