Lead is a toxic heavy metal that affects the lives of millions of people every year. Lead occurs naturally in the Earth’s crust and is mined for use in products such as pigment in paints, dyes and ceramic glazes; caulk; pesticides; ammunition; pipes; weights; cable covers; car batteries; and sheets to protect people from radiation. Lead is often combined with other metals to form alloys, and, until recently, was commonly added to gasoline to increase octane ratings.
Environmental levels of lead have been increasing for hundreds of years, and are only just starting to decrease in response to greater awareness of its harmful effects. Today, much of the lead in circulation exists in car batteries, also called used lead-acid batteries (ULAB). Of the six million tons of lead that are used annually, approximately three quarters go into the production of lead-acid batteries. [1] Of these batteries, 97% are eventually recycled to retrieve the lead. [2] The high levels of recycling are, in part, due to the increase in lead prices over the last 15 years.
In low- and middle-income countries, common industrial sources of lead pollution include mining, primary and secondary metal smelting, steal and iron production, car battery recycling, and the production of pigments. Lead that is released into the air is brought back to Earth by precipitation or as particulate matter falling to land or surface water. Once lead reaches the top layer of soil, it tends to adsorb to soil particles that can be blown around as dust or be tracked throughout a community by people walking in the impacted area. The lead in the soil can also reach surface water bodies as part of storm water runoff. Water movement through the soil can transport lead to ground water, which is used for drinking water and crop irrigation.
Lead often enters the environment through releases during the mining process for lead and other metals, as well as from factories that make, use, or recycle lead or lead compounds. Lead can also be released into the air by burning coal, oil, or lead-containing waste. Once lead is on the ground it can remain in the upper layer of soil for many years. Lead can migrate into ground water supplies, particularly in areas that receive acidic or “soft” rainwater. Furthermore, levels of lead can build up in plants and animals when the surrounding environment is contaminated.