All around you there's EM radiation in the order of watts. There is enough to power a radio from the antenna alone if it's big enough. No effects have been observed this far, aferage lifesoan continues to grow in spite of EM, chemical, biological, superbug and whatnot pollution. While high EM has been noted as a possible cancer factor, we're talking people living under power lines, which took in equivalents of hundred of watts hour. The phone doesn't exceed 4 W under the worst conditions and not for 24 hours for decades. Even so, the emissions of you phone is a drop in the bucket, considering that in that area you have several APs, GSM, (several networks), a few tens of radio stations, a few TV stations, walkie-talkies from taxis, satellite coverage, power line hum, EM from electronics and PCs, lighting, space humming, and all kinds of other stuff all over the spectrum. Not to mention hight energy stuff from the sun and ionizing stuff from space. Don't let EM spoil your N900.
it would require so much time to filter what is good to keep and what not that it will be completely useless....