lead

Heavy, soft, malleable, grey, metallic element, atomic number 82, relative atomic mass 207.19. Its chemical symbol comes from the Latin plumbum. Usually found as an ore (most often as the sulphide galena), it occasionally occurs as a free metal (native metal), and is the final stable product of the decay of uranium. Lead is the softest and weakest of the commonly used metals, with a low melting point; it is a poor conductor of electricity and resists acid corrosion. As a cumulative poison, lead enters the body from lead water pipes, lead-based paints, and leaded petrol. (In humans, exposure to lead shortly after birth is associated with impaired mental health between the ages of two and four.) The metal is an effective shield against radiation and is used in batteries, glass, ceramics, and alloys such as pewter and solder.

Lead has been the traditional composition of bullets since the 15th century. In spring 1999, the US Army began issuing soldiers with environmentally friendly bullets containing no lead, which contaminates the soil. The army's projected deadline for eliminating all lead bullets is 2003.