Earlier quoted context omitted.
But actual power lines and other total EM pollution might be. Perhaps at some point local power use (thus LF induction) exceeded safety margins afforded by physical isolation between cables and people?
Power line EM emissions have essentially ~nil power and a human is a very poor antenna for those frequencies (top of the head ~6 orders of magnitude too small), even at very high harmonics (n=20 is just one kilohertz).
https://www.cancer.gov/about-cancer/causes-prevention/risk/r... Kinda meh on cancer though not quite no effect.
Experiments abound on pubmed and so on, such as http://www.sciencedirect.com/science/article/pii/S2305050015...
This would be easy to check by comparing rural and metropolitan areas with control for other pollution...