My son is a tattoo artist. On the days he goes directly from cleaning up after doing a tattoo he has tested positive. On the days he goes from home he has tested negative. Their cut off level is at 500. He uses madacide, 70% isopropoonol, 70% isopropyl alcoholl, and avagard hand antiseptic which contains 70% ethyl alcohol. Could this be the cause of his positive results even at a 500 level. The testing site claims these products will not cause it. He has 3 months of probation left.