I've always felt that they were but have kept one in my house because it's so damn convenient.. but a niggling feeling every time I nuke something is...'am i now eating cancer'?
No. Microwaves are in the middle of the electromagnetic spectrum between infrared light and radio/television waves. In this range of the spectrum (relatively long wavelength/low frequency), the oxygen-hydrogen bonds in water absorb this energy, are excited and heat up. Nothing less, nothing more. There are no direct chemical or nuclear changes in the molecular composition of the food.
If you want a margin of safety then leave the room while it is running and then wait at least one minute after it stops before opening it to get what you heated.
Does your question also apply to Toaster Ovens as well (or just microwave ovens)...because I just bought a new one the other day, Curious
There is increasing research to suggest, that even though the above quote might be true, changes are observed on a DNA level. https://www.ncbi.nlm.nih.gov/pubmed/2304485 The youtube vids on experiments with cooled microwaved water and plant growth are novel to watch. (I make no claims.)
The abstract of this article gives the impression that mice cells were placed inside the microwave oven. And afterwards were inspected for changes in DNA. I don't think that it is @LacesOut 's intention to put himself/herself inside the microwave oven.