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Lead is a chemical element with the symbol Pb (from the Latin plumbum) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is silvery with a hint of blue; it tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements.

Lead is used in building construction, lead-acid batteries, bullets and shot, weights, and is part of solder, pewter, fusible alloys, and radiation shielding. It is also used in some cable sheathing, and as a stabilizer in many plastics. Historically, lead was used extensively in plumbing as well as in the manufacture of paint, though its use in these areas has been restricted in many countries to reduce health risks.

Health Effects

Lead is a toxic substance to animals and humans, causing a range of health effects from behavioral problems and learning disabilities, to seizures and death. Children are more vulnerable to lead poisoning than adults. Exposure to lead can occur through ingestion of contaminated water or food, inhalation of lead dust, and ingestion of lead-based paint chips. The use of lead in pipes, paint, and gasoline, although now restricted, has left a legacy of environmental lead contamination.

History

Lead has been used by humans for thousands of years because of its wide availability and ease of extraction. The ancient Romans used lead for making water pipes and wine vessels, as well as for other purposes. However, even in ancient times, the harmful effects of lead were noted by scholars such as Vitruvius and Pliny the Elder. Despite this, its use continued to grow throughout history due to its useful properties.

Production and Recycling

The primary production of lead is through mining and smelting, with secondary production coming from recycled scrap. China, Australia, and the United States are leading producers of lead. Recycling is an important aspect of lead's overall lifecycle, with more than half of the lead used today coming from recycled sources, particularly old lead-acid batteries.

Environmental Impact

Lead can accumulate in the environment, leading to soil and water contamination. It can enter the food chain, posing risks to animals and humans. Efforts to reduce lead pollution include laws limiting lead emissions from industrial plants, removing lead from gasoline and paint, and promoting battery recycling.

Regulation

Due to its toxicity, the use and disposal of lead are heavily regulated in many countries. Regulations cover air emissions, drinking water standards, lead in paint, and occupational exposure limits. The United States Environmental Protection Agency (EPA) and similar bodies in other countries enforce these regulations to protect public health and the environment.

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