Lead is toxic and is harmful to most of the body's organs, including the heart, kidneys, nervous system, reproductive system, bones and intestines. It is especially dangerous to children because their bodies are still developing. Lead was a common component of paint until 1977, and is still used in certain kinds of paints. It can leak into the water and food supplies. Another major cause of contamination is occupational exposure in industrial settings and plants that process lead-acid batteries.