Studies have shown that long term usage of cellular or cordless phones is associated with what used to be considered a rare form of deadly brain cancer called glioblastoma. 9-years ago Sen. Kennedy died from the same form of cancer.  I've seen a picture of McCain with two cell phones held to his head.  He also had two cell towers erected at his ranch so he could stay wirelessly connected.

https://www.nytimes.com/2008/10/16/us/politics/16campaign.html