Health problems caused by exposure to lead
Lead exposure poses significant health risks, primarily due to its toxic nature. Historically utilized in various applications, such as gasoline, paint, and plumbing, lead has been linked to severe health issues, particularly in children and pregnant women. Acute lead poisoning can result from high dosages, leading to symptoms like gastrointestinal disorders and neurological damage, while chronic exposure to lower levels can have long-lasting effects on the circulatory and central nervous systems. Notably, children are more susceptible, as they may experience lowered cognitive abilities and growth delays from even minimal exposure. Pregnant women face additional risks, as lead can cross the placenta and adversely affect fetal development. Despite regulatory efforts, such as the phase-out of leaded gasoline and lead-based paints, concerns about lead exposure remain prevalent, particularly with lingering contamination in older homes and environments. The ongoing challenge is to monitor and minimize lead exposure to protect vulnerable populations from its harmful effects.
On this Page
Subject Terms
Health problems caused by exposure to lead
DEFINITION: Heavy and malleable bluish-white metallic element that occurs naturally, at low levels, in the environment
Excessive, long-term exposure to lead—which has been used in the manufacture of gasoline, paint, and water pipes, among other things—may lead to severe health problems and even death.
Lead is a relatively rare element that has been mined and used for centuries. The of lead in the earth’s crust is only 12.5 parts per million (ppm), and most of this lead is found in the ore galena. Evidence of the use of lead dates back at least 5,000 years, and the environmental impacts of smelting and using lead can be detected in ancient bog deposits in England and Spain that date back at least 2,800 years. Lead was used by ancient European and Chinese civilizations for plumbing, drinking vessels, food and wine storage containers, weights, and ornaments. Considerable evidence from human skeletons indicates that lead poisoning was a significant problem in ancient Roman society.
Lead is now the fifth most commonly used metal in the world. The majority of lead is used for the manufacture of lead-acid batteries, but much of the lead mined in the twentieth century was used for the production of antiknock compounds (such as tetraethyl lead) that were added to gasoline. Lead has also been used in the manufacture of some paints, ceramic glazes, ammunition, and solder, and it is the preferred material for preventing unwanted to X-rays. Because of the widespread burning of gasoline with tetraethyl lead for many years, which caused the transport of lead compounds throughout the atmosphere, lead may be the most widely distributed of the heavy metals. Measured levels of lead in remote areas have been found to range from three to five times higher than natural background levels.
About 60 percent of lead exposure for adults comes from food, both fresh and canned. Lead is naturally taken into plants, but it also accumulates in food because of dry deposition from the atmosphere and storage in cans. Approximately 30 percent of the lead in humans comes from the inhalation of air, although this exposure has decreased dramatically since leaded gasoline was phased out of use for most vehicles in the United States in the late 1970s. Lead is also released into the atmosphere through the burning of solid waste, coal, and oil. Tobacco is an additional source of airborne lead exposure. The remaining 10 percent of lead in humans comes from water. Much of the exposure through water is the result of lead pipes, fixtures, and solders used in older plumbing. An additional significant exposure route for children is through ingestion of chips or flakes of the lead-based paint that was used in many homes in the past; children may also ingest dirt containing lead paint residues.
Lead Poisoning
Lead is a toxic element that can cause both acute effects from short-term high-dosage exposure and chronic effects from long-term exposures at lower levels. Children and pregnant women are at particularly high with regard to lead exposure. Children may ingest higher levels of lead from soil, and the effects of lead poisoning in children begin at lower blood levels. Pregnant women are at high risk because lead can substitute for calcium in bones and may be mobilized during periods of calcium deficiency, such as pregnancy. Lead released into a pregnant woman’s blood can cross the placenta and cause damage to the fetus or even miscarriage.
At high levels, lead poisoning can cause severe brain damage, gastrointestinal disorders, kidney damage, and even death. At lower levels, the symptoms of lead poisoning are not as severe; they include constipation, vomiting, abdominal pains, and loss of muscular coordination. Because these symptoms may also result from other causes, it is not always clear when lead poisoning has occurred.
The long-term chronic effects of low-level lead exposure may lead to many health problems, primarily with the circulatory and central nervous systems. Most of the lead that is absorbed ends up in the blood, and its general residence time is between two and three weeks. Long-term exposure can lead to disruption of the formation of heme in the blood and cause other enzymatic disorders. Anemia can result, with the symptoms arising at much lower blood lead levels in children.
Lead is also a neurotoxin that affects primarily workers in lead-related mining and manufacturing, as well as children. In children, exposure to lead may lead to lowered mental capabilities, but it is not yet clear to what extent this can be established. It is known that lead poisoning can cause hearing disorders and even slow the growth of children. Chronic exposure to lead can cause blood-pressure problems and interference with vitamin D metabolism. Reproductive problems such as low sperm counts and spontaneous abortions have also been linked to lead exposure.
It is not yet clear whether lead is a carcinogen. Studies on workers in lead industries have been inconclusive with regard to links between cancer and lead exposure, but animal studies have shown an increase in cancers of the kidney. The US Environmental Protection Agency (EPA) considers lead to be a probable human and has classified it as a Group B2 carcinogen.
Because of its highly toxic nature, lead has been extensively studied and closely regulated in the United States and many other countries. Lead is one of the six primary pollutants regulated by the Clean Air Act, and the EPA is required to establish ambient outdoor air-quality standards for this pollutant. The removal of leaded gasoline from the U.S. market reduced the concentrations of lead in the atmosphere by 93 percent between 1979 and 1988. In addition, the removal of most lead-based paints has reduced the risk of accidental ingestion of lead by children. As a result of these and other regulations, the lead exposure of most adults and children has been significantly reduced. However, lead levels in the blood of many children indicate that exposure is still a great concern.
Bibliography
Angrand, Ruth C., et al. "Relation of Blood Lead Levels and Lead in Gasoline: An Updated Systemic Review." Environmental Health, vol. 21, no. 138, 27 Dec. 2022, doi.org/10.1186/s12940-022-00936-x. Accessed 20 July 2024.
Casdorph, H. Richard, and Morton Walker. Toxic Metal Syndrome: How Metal Poisonings Can Affect Your Brain. Garden City Park, N.Y.: Avery, 1995.
Timbrell, John. “Environmental Pollutants.” In Introduction to Toxicology. 3d ed. New York: Taylor & Francis, 2002.
Warren, Christian. Brush with Death: A Social History of Lead Poisoning. Baltimore: The Johns Hopkins University Press, 2000.
"What Are Some of the Health Effects of Lead?" US Environmental Protection Agency, 5 Mar. 2024, www.epa.gov/lead/what-are-some-health-effects-lead. Accessed 20 July 2024.