Vegetables are carcinogenic?

Apparently, way before humans ever thought to create pesticides, plants already had their own internal mechanism to deter animals from eating them.  I was surprised when I read on the food site I linked to a couple days ago that celery produced carcinogenic compounds.  You're not supposed to eat bruised celery because the bruising starts a process that increases the production of that carcinogen by 100x.  The same is true of several other vegetables apparently.

I found these next two pages while I was looking for more information about this:
http://mathforum.org/~josh/alfalfa.html
http://potency.lbl.gov/herp.html

Bruce Ames, a biochemistry professor at UC Berkeley was the one who started research into the extent of this.  It's rather scary looking at all that and seeing what produces carcinogens - potatoes, spinach, coffee, peanut butter, raw mushrooms, coffee, alcohol, anything that's been browned...

However, Ames conclusion is not to severely restrict your diet but to realize that you probably encounter many more carcinogens in your diet that are naturally produced than are residual chemical pesticides or food additives.  Go ahead and be aware (don't eat bruised vegetables!), make sure you take in foods and nutrients that have anti-carcinogenic properties ("cruciferous" vegetables, vitamins A, C, E, and selenium), and eat high fiber foods so that food does not stay in your system too long.