Does your kid know you are freaking out over this trip? It really doesn't bode well for your confidence in him to explore the world.

I went to Greece for year when I was 19.... and all was well....very well in fact.....I studied, met new friends, and fell in love with a new country that changed my life even to this day 45 years later.....

I know it is not easy...but you cannot control what you cannot control...and travel always is a little out of control.

Let him have his adventure.