High power electric transmission lines (the uninsulated kind) -- studies suggest they are attracting radon from the ground rock, which is probably related to health problems in people, including (but not limited to) leukemia in children [note: association does not equal cause-and-effect]. We continue to expand on their use to this day with little additional study. Our dependency on technologies that destroy us from the inside out continues on. If they found cell phones really did cause brain cancer -- would people stop using them? -- or demand an easy cure for brain cancer that comes in pill form? --or would they just text while driving all day instead? Yet another aspect of human behavior that I find cosmically hilarious. Ah... but I'm probably destroying my eyes on a computer screen as I type this...