Lead is a naturally occurring element that people have used for hundreds of years. Human activities have spread lead widely throughout the air, water, soil, plants, animals, and man-made constructions.  Lead has many uses; however, lead paint is a primary source of environmental exposure to lead. Lead was originally used in paint for several reasons. It was used as pigment because it made colors more vibrant, it preserved the paint in that it made the paint more weather resistant, it resisted the growth of mold and mildew, and it helped prevent corrosion of metal surfaces. Between 83 and 86% of all homes built before 1978 in the United States have lead-based paint in them. The older the house, the more likely it is to contain lead-based paint and to have a higher concentration of lead in the paint.

Most human exposure to lead occurs through ingestion or inhalation. As lead paint deteriorates, peels, chips, is removed (e.g., by renovation), or pulverizes because of friction (e.g., in window sills), lead chips and dust can get on surfaces and objects that people touch. Settled lead dust can re-enter the air when people vacuum, sweep, or walk through it. Lead then enters the body through normal hand-to-mouth activity and inhalation.

If exposed, lead can have numerous health affects. The most sensitive targets for lead toxicity are the developing nervous system, the blood and cardiovascular systems, and the kidney. The effects are the same whether it is breathed or swallowed. Potential affects in children are damage to the brain and nervous system, Behavior and learning problems, Slowed growth, Hearing problems, and Headaches. Potential affects in adults are Difficulties during pregnancy and other reproductive problems in both men and women, high blood pressure, digestive problems, nerve disorders, memory and concentration problems, and muscle and joint pain.