Let the hive mind of Engadget get that for you.
"As someone who doesn't reside in the USA, I was wondering what would be the best way to get internet for my computer in the US for a couple of weeks? If it were Europe I know I'd look for some prepaid data. Is there anything similar offered by American carriers? A MiFi or a data SIM that I can tether from would work, but I'm trying to maintain a tight budget. Help!"
"breathing pure oxygen multiplies the chance by a factor of 8 (!)"
And what are the odds that you will be breathing pure oxygen more than a few seconds in your entire life ? Since the immense majority of us live on a planet where pure oxygen is only available in very rare and disseminated points, chemical labs and industries mainly, you can eliminate pure oxygen as a risk factor of any kind to your health. Earth atmosphere is only 20% oxygen you know, the rest being mostly nitrogen.
So your maths about risk factor are quite moot, we spend much time using GSMs and none breathing pure oxygen.
Did you know that there was a 100% death risk if you happen to be within a 2 meters radius of a fusion bomb when it explodes ?
Cellphone radiation is far less dangerous so clearly we should not worry about it, sure :)