Breathing of contaminated air is the most common way that workplace chemicals enter the body. Some chemicals, when contacted, can pass through the skin into the blood stream. The eyes may also be a route of entry. Usually, however, only very small quantities of chemicals in the workplace enter the body through the eyes. Workplace chemicals may be swallowed accidentally if food, hands, or cigarettes are contaminated. For this reason, workers should not drink, eat, or smoke in areas where they may be exposed to chemicals.