Occupational Safety & Health Administration rules require employers to provide employees protection for the head, eyes, ears, arms, hands, wrists, fingers, legs, feet and toes. In fact, just about every part of the human anatomy is spelled out in federal rules except for the body's largest organ -- the skin. In the workplace, skin can be exposed to a variety of irritants that can cause acutely painful rashes. The most common types of skin rashes are contact dermatitis and eczema. Both can have a negative effect on a worker's performance and lead to sharply reduced productivity and lost work days. Three other skin diseases that all employers and workers should be acquainted with are hives, shingles, and skin cancer.