Why can't I dump nuclear waste in my front lawn?

This week in class we began talking about externalities; effects on those who are outside of a transaction. In other words effects caused by the producer or consumer and felt by someone who is not in either of thsese categories. I found it somewhat intuitive that one would expect a large company to pay for damages they caused to someone who had no stake in the matter at all. However, in my mind, it does bring into question some private property rights. If I own my own land in the middle of the city, and decide to build a small power plant on it and sell the power, but my manufacturing processes create massive amounts of air pollution then its pretty much a given that I'll be having quite a number of legal problems. And it seems logical that I would, afterall my business is causing people to breate in toxic air. However, if I own my own house and the land it sits on, why am I legaly required to get permits in order to build on an addition, or even redo a bathroom? I have heard the argument that this is to maintain standards for others safety, in otherwords: to prevent negative externalities. This is somewhat understandable, but then again I have to view this as an infringement on personal rights. Where do you draw the line with preventing 3rd parties from being harmed? As with all concepts in economics its easy to see the extremes, but as to where the balance is found?...its anybody's guess.