I've been loading with another employee who seems to enjoy throwing boxes. Not simply dropping them onto the floor from waist height, throwing them. Sometimes they will pick a box up off the rollers and lift it to chest height then forcefully throw it onto the floor. I have heard items in the boxes break. One day there was a mis-sorted hazmat, they threw it out of the truck from the trailer, over the platform onto the floor. Should I mention this to my supervisor, steward, safety (because of the hazmat) or all of them?