Lead

Lead is a naturally occurring metal found in small amounts in the earth’s crust. It is considered a heavy metal because of its high density and toxicity at low concentrations. Although it is toxic to humans and animals, it is used in industrial activities such as burning fossil fuels, mining, and manufacturing.¹ Lead is useful because of its malleability, ductility, low conductibility, and resistance to corrosion.² It can also be combined with other metals to form alloys. These lead compounds can be found in pipes, batteries, weights, ammunition, cable covers, caulk, sheets to shield radiation, and in pigments used in paints, dyes, and ceramic glazes.³

Human exposure occurs predominantly in industries and occupations that use lead, like leaded gasoline, lead smelting and combustion, pottery, boat building, battery recycling, lead-based painting, and the arms industry.⁴ Lead-based paint was prevalent until 1978, as was plumbing made of lead or with lead solder (until 1986). But lead can leach out of pipes and into drinking water – especially when the water is acidic – causing exposure by ingestion. Similarly, as paint peels and makes its way into dust around homes, people can be exposed through inhalation.⁵ In recent years there has been a dramatic reduction in lead use due to concerns about its health effects and increased regulations.⁶Even so, renovation or repair work in older buildings can expose workers to lead.⁸

Lead exposure can cause toxicity in almost any organ or organ system in the body. It is particularly harmful to the brain, the central nervous system, the hematopoietic and cardiovascular systems, the reproductive system, the kidney, and the liver. The International Agency for Research on Cancer (IARC) also classifies lead compounds as probably carcinogenic. It is possible for humans to experience adverse health effects due to acute lead exposure, but this is less common than chronic exposure to low levels of lead. Acute exposure is likely to occur in an occupational setting, although this kind of exposure has decreased because of efforts to curtail lead use. Regulations restricting environmental lead concentrations have helped to reduce chronic environmental exposure, but people continue to be exposed through household materials. Lead cannot be fully removed from the body, so prevention and reduction of exposure is critical.⁹

Lead is particularly damaging to children. Any level of exposure can result in irreversible effects such as brain damage causing neurobehavioral development abnormalities, lower IQ, hyperactivity, slowed growth, hearing problems, and anemia.¹⁰ There are even rare cases of seizures, coma, and death resulting from lead ingestion. Children are particularly susceptible because they absorb more lead than adults do, and their brains and nervous systems are still developing, making them more sensitive to damage. Children’s propensity to put their hands and other objects in their mouths also creates more opportunities to ingest lead from dust or soil. Other possible routes of exposure include eating and drinking contaminated food or water, using kitchenware that contains lead, inhaling dust containing lead, or playing with toys with lead paint.¹¹

Lead accumulates in the body, where it is stored in bones.¹² This has particular repercussions for women who become pregnant, as lead is released from their bones and can pass through the placenta to the fetus. This may result in premature birth or miscarriage; damage to the baby’s brain, kidneys, and nervous system; or increased risk of cognitive or behavioral problems.¹³

Because lead is non-biodegradable, it also accumulates in the environment. The soil, air, and water around industrial sites like mines, refineries, smelting sites, power plants, incinerators, landfills, and hazardous waste sites often have substantially higher levels of lead.¹⁴ When it is released into the air from industrial activities it is capable of traveling long distances before falling to the ground, where it tends to settle on soil particles.¹⁵

The United States has a number of federal and state laws that regulate lead use in paint, dust, soil, the air, water, and waste disposal. The Environmental Protection Agency (EPA) administers many of these laws, including the Toxic Substances Control Act (TSCA), the Residential Lead-Based Paint Hazard Reduction Act of 1992, the Clean Air Act, Clean Water Act, and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), among others. Strict standards in the US have led to the reduction of lead concentrations in air, water, soil, consumer products, food, and occupational environments. However, it continues to be used frequently in developing countries.

Materials

Metal

Was this insightful?

Yes No

Related Terms

Materials

Was this insightful?