There are a lot of concerns about toxins these days. One of which is the vapors left behind after you spruce up that back room with a fresh coat of paint.  I am not an expert here, but of course less toxic is best, but they are very pricey! Check out this artical on the values or non toxic paints to see for yourself.  http://www.eartheasy.com/live_nontoxic_paints.htm