This is a problem in the saw milling industry too. Being around large band saws, planers, debarkers, and other heavy machinery can be dangerous. People occasionally die. If you can not pass a drug test, they do not want you working in their sawmill.
This is also why many sawmills no longer allow you to tarp a truck on their property, even with a tarping station. This is because drivers have fallen off of the top of a loaded flatbed truck when they were trying to tarp a load. Again, this has resulted in deaths. FYI, a tarping station is where you put on a harness and hook into an over head arm that keeps you from hitting the ground if you fall off the trailer.
My only familiarity with the lumber industry and the saw mill industry was during the summer after high school graduation when I worked as a seasonal forestry fire fighter out of northern California fire station. One of our controlled burns was working together with a lumber outfit and once we had to go and put out a blaze in the long and tall heaps of sawdust and debris on land next to the mill. The latter incident was suspicious to me and my fellows, because just the evening before, after dinner, our boss had us all ride in one of our fire trucks into the nearby town where he stopped and chatted for awhile with some man at that same lumber mill. This was near the very end of the fire season and some of us figured our boss was corrupt and just found a way to keep the season extended, because once the fire season would be declared officially over for our area he would be laid off until the start of the next fire season. That was the second time in the last two weeks of the fire season when we had gone out during the day in one of the fire trucks on some nearby country road and within 24 hours were called out to the same area on a fire. Hmmmmm.