ALWAYS rinse off at the clean outlet of the water trailer after any chemical interactions…powdered or liquid. Had an old guy that couldn’t figure that out and complained of headaches, back before single point filling of both tanks and you opened the top to put the hose in each tank to fill/dose chemicals into tank …had chemicals on his wet hands when lighting a cigarette because he kept rinsing his hands from his chemical tank on the tractor and not the clean water trailer. I finally caught him doing it one day to figure it out and tried to drill it in his head. He was doing it again within the week…so he didn’t have to get down off the tractor to go over to the water trailer, even though he had to do it anyway to shut off the trailer pump motor….. Dummy.