One of the main tragedies of child labor was how work robbed children of their youth. Mill workers often toiled for ten to twelve hours per day with few breaks for rest. Because of their work, child workers seldom attended school. Also, the long working shifts resulted in a variety of injuries, ranging from blisters to muscle and neck or back strains to circulation problems. The machinery was dangerous, and fingers or arms could be become caught and crushed or torn from the body. The noise of the machinery could cause hearing loss. In addition, workers were exposed to a variety of communicable diseases such as smallpox and measles.