Human contact doesn't just mean human in this instance.... it means your fish are in capable of contacting the glass... Personally I would be using Acrylic but I would also say that 1" in this would work just fine if it's tempered since you didn't mention what you were pricing out (plate or tempered).
but then again ... never hurts to go overboard on the weakest part of tanks...
but then again ... never hurts to go overboard on the weakest part of tanks...