Exactly what he said.Short answer your fine.
The THC you come into contact with will be the Trichomes. the plants secreted elements are not large enough to enter the body through your pores. you would be able to touch frosty colas and get trichomes all over you and still pass a drug test. just dont lick your fingers!! if you eat the trichomes they will enter your body and you WILL fail a drug test. if it makes you feel safer you can use non-powdered gloves when working with your plants, this will help keep your bodies toxins off of your plants too.