Mercury (Hg) is a naturally occurring metal found throughout the environment. It is a liquid at room temperature, combines easily with other metals and expands and contracts evenly with temperature changes. Because of these properties, mercury has been used in many household, medial and industrial products. Although mercury performs many useful functions in our workplaces and homes, it is toxic and can impair our health. Mercury is a potent neurotoxin, meaning that it interferes with the way nerve cells function. Mercury poisoning causes a decreased ability to see, hear, talk and walk. It can cause personality changes, depression, irritability, nervousness, and the inability to concentrate. It can also cause damage to the brain, kidneys and lungs. Mercury is a particularly serious problem for pregnant women and children. Fetuses and young children suffer the greatest risk because their nervous systems are still developing. They are four to five times more sensitive to mercury than adults.