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Lead is a naturally occurring element in the earth. When mined and processed, it is a soft, malleable metal that has been used in all sorts of products, including pipes (from as far back as ancient Rome!), car batteries, paint and gasoline. Lead occurs naturally in certain minerals, such as galena (PbS). Typically, small amounts of lead are also naturally present in coal.

While lead is a very useful material, it can cause health problems — such as high blood pressure, muscular weakness, even memory loss — if it gets inside the human body. People can be exposed by breathing dust from lead-based paint or contaminated soils, or by eating or drinking food or water that contains it. Ingestion of lead–based paint chips or dust is the leading cause of lead poisoning in U.S. children. Children are more sensitive to exposure than adults because their bodies are still developing. Lead can also be found in drinking water. For public water systems, the U.S. Environmental Protection Agency set an action level for lead in drinking water of 0.015 milligrams per liter (15 parts per billion). By comparison, this ratio is roughly equivalent to 15 seconds over 32 years! Lead can enter groundwater from natural and manmade sources. It can leach into drinking water through contact with lead-containing materials such as pipes, fixtures, or solder. The pH, temperature, and time in contact can all affect the amount of lead that leaches (more acidic or hotter water can leach more lead).

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