Just a quick caveat here, I am a smoker, much to the offspring's chagrin. I must admit that in the last few years we no longer smoke in the house and have certainly cut back but alas, can't just seem to quit.
Watching documentaries about cancer is always scary but I did force myself to recently watch Wendy Mesley's documentary on CBC called "Chasing the Cancer"
http://www.cbc.ca/consumers/market/files/health/cancer/blood.html

If you want to be scared just go ahead and read the story. Seems that very little of what we use in our daily lives is actually safe and most contain some form of carcinogens. I mean, who knew that face creams to fight our wrinkles can actually cause cancer? Stuff that we use daily to clean our houses? Why I ask myself is the only industry to be picked on the tobacco industry? Why do the rest get off scott free? What the heck am I going to do now to clean my house? Oh well, I think I'll just go clean my oven and hope for the best!