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Lead

CASRN 7439-92-1

Physical Properties

Lead is a heavy, low-melting, bluish-gray metal that occurs naturally in the Earth's crust. However, it is rarely found naturally as a metal. It is usually combined with two or more other elements to form lead compounds. Metallic lead is resistant to corrosion.

Uses

Lead has many different uses. It is used in the production of batteries, ammunition, metal products (solder and pipes), and devices to shield X-rays. Because of health concerns, the amount of lead used in paints and ceramic products, caulking, and pipe solder has been dramatically reduced in recent years. In the past, organic lead (as tetraethyl lead) was added to gasoline to decrease knocking and increase engine efficiency. The use of lead as a gasoline additive was banned in 1996 in the United States. Lead arsenate, basic lead arsenate, and lead arsenite were formerly used as herbicides, insecticides, or rodenticides. Until the 1960s, they were widely used to control pests in fruit orchards, especially apple orchards. All insecticidal use of lead arsenate was officially banned in 1988.

Sources of Exposure in Iowa

Lead occurs naturally in the environment, but most of the high concentrations throughout the environment come from human activities. Dust and soil sources include lead that falls to the ground from the air, and weathering and chipping of lead-based paint from buildings, bridges, and other structures. Most of the lead in Iowa soil comes from old houses with paint containing lead. Small amounts of lead from lead pipes or solder may be released into drinking water if the water is acidic or “soft”. Children may be exposed to lead by putting their hands on dusty surfaces or in soil or paint chips containing lead, then putting their hands in their mouths. Children may also chew on painted surfaces or eat paint chips that contain lead. Other sources of lead in Iowa include food, ethnic remedies, and toys imported from Central and South America, eastern Europe, and Asia. Adults may be exposed to lead by working in battery manufacturing or recycling, creating or repairing stained glass windows, and repainting or remodeling older homes.

Health Effects from Large Acute Exposures

The effects of lead are the same whether it enters the body through breathing or swallowing. The main target for lead toxicity in both adults and children is the nervous system. At high levels of exposure, lead can severely damage the brain and kidneys in adults, and ultimately cause death. In pregnant women, high levels of exposure to lead may cause miscarriage. High levels of exposure in men may damage the organs responsible for sperm production.

Health Effects from Smaller, Chronic Exposures

Long-term exposure of adults to lead at work has resulted in decreased performance in some tests that measure functions of the nervous system. Lead exposure may also cause weakness in fingers, wrists, or ankles, and small increases in blood pressure, particularly in middle-aged and older people. Lead exposure may cause anemia. Children are especially sensitive to lead exposure. About 99% of the amount of lead taken into the body of an adult will leave the body in the waste within a couple of weeks, but only about 32% of the lead taken into the body of a child will leave in the waste. At blood lead levels as low as 10 micrograms per deciliter (µg/dL), children's intelligence, hearing, and growth are adversely affected.

Protection from Exposure

The most important way to decrease exposure to lead is to know about sources of lead at home and avoid exposure to these sources. Homes that were built prior to 1978 may have been painted with paint that contains lead. Decaying, peeling, or flaking paint can introduce lead into household dust. Windows and exterior surfaces are most likely to have deteriorated paint. Interior and exterior areas where the paint is breaking down should be safely repaired and repainted. Regular hand and face washing to remove lead dusts and soil, especially before meals, can reduce accidental swallowing of lead on the skin. Regularly cleaning the house of dust and tracked-in soil can reduce exposure to lead. Door mats can reduce the amount of soil that is tracked into the home; removing shoes at the door will also help. Planting grass and shrubs over bare soil in the yard can reduce pets’ and childrens’ contact with soil and tracking soil into the home.