When it comes to substance abuse like smoking or abuse of intoxicating drugs, it is very difficult to determine what a “safe” limit of exposure is.  Quite often, the initial exposure to mood altering substances like nicotine occurs during the teenage years. The period of adolescence is marked by a tendency towards risk-taking behavior which often results in ‘experimental’ exposure to psychedelic substances. Adolescents who tend to flirt with danger in this fashion are often convinced that a small trial will not actually have lasting damaging effects. However, research on the development of prefrontal cortex in similarly age-matched animals says otherwise.

via Smoking and Adolescent Brain Development | Brain Blogger.