Smoking!

Personally I am not for or against smoking, I think that adults who smoke are at full capacity to decide whether right or wrong in their lives, but young parents feel that if you should worry about providing the right information. In the long run is a vice that if practiced daily in a disproportionate, will stop their activity.

Links

http://kidshealth.org/teen/drug_alcohol/tobacco/smoking.html

http://health.nytimes.com/health/guides/specialtopic/smoking-and-smokeless-tobacco/overview.html

http://www.netdoctor.co.uk/health_advice/facts/smokehealth.htm