Yes, it is our responsibility as leaders to be able to identify any hazard to our youth. The program is not solely camping and merit badges. It's our duty as moral people and good citizens to be able to help the youth we're entrusted to live healthy, full lives, up to and including alcohol/drug prevention. If we're able to identify a problem and alert the Scout's parents of our concerns, it may be dealt with by the youth's family, minister, counselor, etc. before the problem infects the troop and you end up with addicted or dead boys.
The number of abused drugs is on the rise and it is very easy to hide this abuse, especially when the drugs of choice are prescription medicine and over the counter supplements (ritalin, GHP, etc.). Any training that would enable us as leaders to prevent or identify drug use would be welcome.