Lead is a soft, dull-grey metal that is extracted from ore deep within the earth’s crust.[viii] It has a shiny metallic luster after being freshly cut, and is highly malleable and corrosion resistant.[x] It also has a high propensity for adsorbing x-rays and gamma rays.[xi] Lead has the highest atomic mass of all other stable, non-radioactive elements. Lead is found in both particulate (Pb) and dissolved forms (Pb2+) in industrial stormwater runoff.
Lead is used for its unique characteristics although it is now less widely used in domestic products because of its toxicity to humans.[xii] Domestic uses of lead in gasoline and paint have stopped in the U.S. and other countries. Common uses of lead today are lead acid batteries as used in automobiles, bullets and shotgun shot, fishing sinkers, industrial grade and non-domestic paint, boat keels, radiation shielding, and soldering.[xiii]
Lead enters the environment through the manufacture and use of consumer products, and by contamination of soils and water. Groundwater can become contaminated by mine dewatering operations.[xvii] Other examples of contamination sources include lead-based paints on buildings pre-dating the 1970’s.[xviii] and industries that manufacture, recycle, demolish, or refurbish products contain lead. Lead in these forms can make its way into waterways and human freshwater drinking sources through stormwater runoff.