Just more Reefer Madness nonsense!
Those who are really trying to keep kids safe would FIRST use their efforts to keep them away from booze, tobacco and prescription drugs. Data direct from the  CDC shows that tobacco, alcohol and prescription drugs are far more dangerous than cannabis and directly cause over 650,000 deaths per year in the US each and every year.  This plus another 21,000 traffic fatalities directly caused by alcohol and pharmaceutical drug intoxication. The numbers continues to increase annually. 

US CDC Figures on numbers of deaths per year in the USA:

*   Prescription Drugs: 237,485 + 5000 traffic fatalities 
*   Tobacco: 390,323
*   Alcohol: 88,013 + 16,000 traffic fatalities 
*   Cocaine: 4,906
*   Heroin: 3,365
*   Aspirin: 466
*   Acetaminophen (Tylenol):  179
*   Marijuana: 0, none, not a single fatal overdose in all medical history and almost no traffic problems

So, which is safer?????