Lead
Lead is a metal found naturally in the earth's crust.1 In nature, it is found more often in chemical compounds than as a pure metal. Even minute exposures can have devastating and permanent effects on humans, which is most unfortunate considering how widely lead has been used throughout human history.
Uses of Lead
A Brief History of Lead UseLead's use dates to before 3000 BC, at which time mines in Spain and Greece began to expand production. This was the beginning of a global atmospheric redistribution of lead. The Roman Empire used lead widely. The Latin word for lead is plumbum, from which lead's chemical symbol, Pb, and the word “plumbing” are derived. Lead was likely widely found in water and many foods throughout the Roman Empire. Lead water pipes and cooking pots were common, with lead pots even recommended for use in preparing the sweeteners used in food and wine.2 More Recent Uses
Paint. Lead was added to paint for many years, providing color, durability, quicker drying times and other benefits to the paint. In 1909, childhood lead poisoning was linked to lead-based paints in cribs. In 1922, the League of Nations banned lead-based paint, but the United States did not adopt this rule until 1971, when the Lead-Based Paint Poisoning Prevention Act was passed. Lead paint was discontinued in the US in 1978. Homes in the US may still have lead paint present, both inside and outside.
graphic from the US Environmental Protection Agency3 Canned foods. For a time, canned foods were a significant source of lead exposures due to poor quality solder joints in cans. Gasoline. The addition of lead to gasoline is said to be one of the greatest public health failures of the 20th century. When lead was first added to gasoline in 1922 to reduce engine knocking, its harm was already well established.4 A 1965 report in the US concluded that human use of lead creates high levels of lead in the environment. In 1973, the US EPA began phasing lead out of gasoline. Even though the Reagan Administration backpedaled on regulations starting in 1981,5 the primary phase-out of lead was completed in 1986. Even then, some states such as Washington still sold leaded gasoline until 1991. A 1994 study found that between 1976-80 and 1988-91, blood lead levels dropped dramatically in the US. The prevalence of blood lead levels 10 μg/dL or greater for children aged 1 to 5 years declined from 85.0 percent to 5.5 percent for non-Hispanic White children and from 97.7 percent to 20.6 percent for non-Hispanic Black children. The researchers concluded that "the major cause of the observed decline in blood lead levels is most likely the removal of 99.8 percent of lead from gasoline and the removal of lead from soldered cans."6
data from Pirkle et al.7 To complete phasing lead out of gasoline, the World Bank called for a ban on leaded gasoline in 1996. The European Union banned lead in gasoline in 2000. Water. Drinking water has been—and continues to be—contaminated by lead in water pipes and solder. Other products. Because lead is cheap, it still can be found in many products, especially products for children, as detailed below on this page. Timeline of Lead Use in Gasoline and Paint1887: US medical authorities diagnose childhood lead poisoning 1904: Child lead poisoning is linked to lead-based paints 1909: France, Belgium and Austria ban white-lead interior paint 1914: Pediatric lead-paint poisoning death from ingesting crib paint is described 1921: National Lead Company admits lead is a poison 1922: League of Nations bans white-lead interior paint; US declines to adopt although countries throughout Europe do so 1943: A report concludes eating lead paint chips causes physical and neurological disorders, including behavior, learning and intelligence problems in children 1971: US Lead-Based Paint Poisoning Prevention Act is passed 1973: US EPA begins to phase out leaded gasoline 1978: Lead-based house paint is discontinued in the US 1986: New, lower limints on leaded gasoline are implemented in the US 1996: World Bank calls to begin phasing out leaded gasoline 2000: European Union bans gasoline with a lead additive
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Common Products Manufactured with Lead8
Lead was also previously added to gasoline and used as a pesticide.
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Because it is easy both to extract and to work with, lead has been used extensively since ancient times in everything from building materials and cosmetics to pots and pans and coloring agents for food.
Lead was added to paint for decades; leaded paint is still available for purchase in some countries; image from Bart Everson at Creative Commons.
Health Impacts of Lead
Even at very low doses, lead toxicity can impact several systems in the human body:9
- Gastrointestinal, including severe cramping and abdominal pain at higher exposures
- Cardiovascular, contributing to the onset and development of hypertension, plus coronary artery disease, peripheral vascular disease, atherosclerosis, stroke, myocardial infarction
(heart attack) and arrhythmias - Reproductive, affecting sperm, fertility, time to sexual maturation, menstrual disorders and pregnancy outcomes including miscarriage, stillbirth and reduced fetal growth. In addition, lead can result in delayed growth in children.
- Renal, including chronic advanced renal disease or impaired renal function
- Hematological, inhibiting the body's ability to make hemoglobin and thereby causing anemia
- Endocrine, impeding the body's ability to convert vitamin D into its hormonal form
- Vision, causing cataracts
- Musculoskeletal, causing gout
- Immune, associated with immune suppression
- Nervous, the most sensitive target of lead exposure, this system includes the brain. Neurological effects are covered in more detail in the table below.
| Effects of Lead on the Nervous System10 | |
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In Children |
In Adults |
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High levels of exposure:
Low levels of exposure:
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High levels of exposure: Low levels of exposure:
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graphic from Toxipedia
"The Institute for Health Metrics and Evaluation (IHME) has estimated that in 2013 lead exposure accounted for 853,000 deaths due to long-term effects on health, with the highest burden in low- and middle-income countries. IHME also estimated that lead exposure accounted for 9.3 percent of the global burden of idiopathic intellectual disability, 4 percent of the global burden of ischaemic heart disease and 6.6 percent of the global burden of stroke."
Lead Storage in the Body
Ingested lead circulates in the blood, but adults eventually excrete most ingested lead. The amount excreted versus the amount absorbed depends in part on the type of lead compound ingested. Lead that is inhaled is almost all absorbed into the body, where it circulates in the blood to organs.12
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image from Just some dust at Creative CommonsLead in blood can take the place of calcium in mineralizing tissues—bones and teeth—and be stored for years or decades until the tissue is demineralized, releasing lead back into the blood. Lead can be mobilized during these periods:13
- Pregnancy and lactation
- Periods of physiologic stress
- Chronic disease including hyperthyroidism and kidney disease
- Broken bones
- Menopause
- Advanced age
Lead can be stored in a girl's or woman's body and passed to a developing fetus and infant many years later. A 1991 study found a higher proportion of learning disabilities among school-aged children whose mothers were poisoned by lead as children.14
Exposure Sources
Lead can be introduced to the body from inhaling dust particles or by ingesting lead on food, from mouthing objects such as toys, or by licking or sucking contaminated fingers. The most common sources of exposure include leaded paint, contaminated water and contaminated soil, but other sources are also a concern.
Lead Paint and RemodelingThe release of leaded paint into dust is a particular concern during remodeling. Great care must be taken to avoid introducing paint dust into the air when scraping, sanding or cleaning deteriorating lead paint. Even very tiny amounts of lead paint are hazardous. One chip of leaded paint the diameter of a pencil eraser ingested by a child can raise the blood lead level to a critical amount requiring immediate treatment, and the level may stay elevated for several years. Because lead paint particles in dust are inhaled, the lead can be absorbed at higher levels than ingested lead. The US Environmental Protection Agency's Renovation, Repair and Painting Program requires certification for any firms performing renovation, repair and painting projects that disturb lead-based paint in homes, child care facilities and pre-schools built before 1978. EPA also publishes guidelines for do-it-yourself remodelers.
image from Brock Builders at Creative Commons |
Dust
Dust in homes with leaded paint or that accumulates on vinyl objects can become contaminated with lead.
Water
Lead Water Crises in Flint and ElsewhereIn 2014, faced with a water fund shorfall, the city of Flint, Michigan, switched from Lake Huron water sourced through Detroit to a cheaper water supply, the Flint River. Even though the river water was many times more corrosive than water from Detroit, the state Department of Environmental Quality was not treating the Flint River water with an anti-corrosive agent, in violation of federal law. Corrosive water leaches lead from plumbing pipes, and soon residents of Flint began reporting serious water quality problems, including health impacts from consuming and bathing in the water. These concerns were ignored or dismissed until scientific and media investigations revealed overwhelming evidence of lead in household water at levels far above regulatory standards.15 Stories like this are neither unique nor new.16 Washington, DC, for example, experienced similar water contamination in the early 2000s, impacting 10,000 people. The contamination was not motivated by financial gain, and it appears there will not be financial support to those individuals who experience the ongoing negative consequences of lead exposure.17
image from George Thomas at Creative commons, modified |
Lead in water generally leaches from plumbing fixtures. The tragic story of water contamination in Flint, Michigan, brought awareness of lead in water pipes to the world's attention in 2015. Unfortunately, Flint's situation was not unique, for lead in pipes is a widespread problem.
Soil
Lead in soil typically comes from deteriorating paint or nearby industrial or commercial activity, such as a gas station, firing range or smelter. Although lead has been phased out of gasoline in the US, soil in past heavy traffic areas can still be contaminated from exhaust. Lead in gasoline is still used in many countries and continues to pollute both air and soil. Lead in soil can be a problem for gardeners and their families. See the Food and Agriculture Environment page for more information.
Food
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image from Ashley Van Haeften at Creative Commons |
Some foods, such as cereals and some vegetables, grown in lead-contaminated soil can contain high levels of lead, as can food cooked or served on lead-glazed ceramic or pottery dinnerware. Spices may be contaminated with lead, as can some candies manufactured in Mexico. Some candy wrappers on imported candy may also contain lead.18
Household Items
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image from Huzzah Vintage at Creative Commons |
Common items that can contain lead include painted toys, keys, toy jewelry such as charm bracelets and necklaces, and vinyl objects such as toys, bibs, purses, lunch boxes, shower curtains and mini blinds. Candles with lead in wicks emit lead into the air when burned. Lead in wicks was banned in the US in 2003, but older candles and candles outside the US may have lead wicks.19
Cosmetics
Some cosmetics, including some lipsticks, have discernable amounts of lead.20 Kajal (kohl) used as a cosmetic primarily by Indian families contains high levels of lead; prolonged application may cause excessive lead storage in the body.21 Sindoor, a red powder used on the scalp by married Hindi women, may also be contaminated with lead.22
Hobby Materials
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image from Bev Currie at Creative Commons |
Hobbies that involve lead-based materials can be sources of exposure:
- Painting
- Auto repair
- Soldering glass or metal
- Making stained glass or glazed pottery
- Molding bullets, slugs and fishing sinkers
Health Remedies
Some ethnic health remedies such as Azarcon or Greta—used by East Indian, Indian, Middle Eastern, West Asian and Hispanic cultures—contain high levels of lead.23 Any use of these remedies can increase lead exposure.
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image from Raul Lieberwirth at Creative Commons |
Tobacco
Tobacco, its smoke and its ash contain lead. Both active and passive (secondhand) smoking can be sources of lead exposure.24
Artificial Turf
Artificial turf playing fields, especially those made of nylon or nylon/polyethylene blend fibers, may contain potentially unhealthy levels of lead dust.25 The crumb rubber infill used with artificial turf is generally made from used vehicle tires, which can contain lead and other metals. Assessments of whether the crumb rubber is potentially harmful are ongoing. See our Built Environment webpage for more information.
Exposure Trends
The blood lead levels of children in the US have decreased substantially since lead was removed from gasoline and paint in the late 20th century.
graph from the CDC’s national surveillance system;26 click to zoom
While exposures to lead have decreased significantly in the US, Black children are still substantially more likely than White children to have elevated blood lead levels—almost three times as likely to have the highest levels.27 See more about vulnerable populations below.
Vulnerable Populations
Fetus, Infant and Child
Because lead is especially damaging to the developing brain and nervous system, the fetus and child are more sensitive to lead exposures than adults. There is no safe level of lead exposure for a fetus or child. Lead impairs nerve cell growth and division, leading to permanent neurological damage.
Children exhibit special behaviors and characteristics that can increase their risk of lead exposure:
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image from Matteo Bagnoll at Creative Commons |
- More hand-to-mouth behaviors which increase the risk of ingestion of lead from paint chips and soil that adhere to hands
- Higher breathing rates than adults, leading children to intake a greater amount of lead-contaminated air
- Shorter than adults, exposing children to more lead-contaminated fumes that are close to the ground
- More lead absorption in the gut than adults, who absorb about 20 percent of ingested lead.28 Children may absorb four or five times that amount.29
Children are more sensitive to lead's impacts, with health effects at lower blood lead levels than adults. A developing fetus can be greatly affected from exposures too low to cause health issues for the mother.30 Further, undernourished children are more susceptible to lead because their bodies absorb more lead if calcium or other nutrients are lacking.31
The Centers for Disease Control and Prevention (CDC) recommends this protocol for testing children's blood lead levels:32
- States should test children at one and two years of age.
- Children should be tested at three to six years if any of these conditions are true:
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image from Damon Nofar at Creative Common |
- They have never been tested for lead.
- They receive services from public assistance programs for the poor such as Medicaid or the Supplemental Food Program for Women, Infants, and Children.
- They live in or frequently visit a building built before 1950.
- They visit a home (house or apartment) built before 1978 that has been recently remodeled.
- They have a brother, sister or playmate who has had lead poisoning.
Occupations Especially at Risk of Lead Exposure33
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Groups Especially at Risk of Lead Exposure34
- Anyone who lives in a home built before lead was banned from paint (1978 in the US). Older low-income housing is a special threat, as the leaded paint may not be maintained properly and thus creates more lead dust in the home and soil.
- Professionals who work in jobs where they may be exposed to lead (common occupations are listed at right)
- Children or pregnant women living or playing near contaminated soil
- Anyone who lives near or downwind from a lead manufacturing or smelting industry, past or present
- People who engage in hobbies that use lead-based materials, and those who share their homes
Reducing Exposures
Personal Prevention
To prevent adverse health effects from lead, avoid exposure to sources of lead:35
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image from Jay Peeples at Creative Commons |
- Dust and mop frequently any spaces that children or pregnant women occupy that may contain leaded paint or other sources of lead that can contaminate dust. Use a damp rag and mop to avoid stirring dust up into the air. Promptly clean the rags and mops after use.
- In buildings built before 1978 (US), keep paint well maintained, especially around windows and wear areas where paint is most likely to deteriorate.
- Children and pregnant women should not be present in housing built before 1978 that is undergoing renovation. They should not participate in activities that disturb old paint or in cleaning up paint debris after work is completed.
- Keep known or suspected leaded objects away from infants and children who are prone to sucking, mouthing or chewing items.
- Avoid purchasing cosmetics that may contain lead, and keep those you have away from children.
- Avoid candy imported from Mexico made with chili powder or tamarind.
- Wash faces and hands of children and pregnant women often to remove lead dust, especially when living in or visiting an area where many houses have lead-based paint either inside or outside.
- Do not use traditional folk medicines which contain lead.
- If you know or suspect your plumbing may contain lead, flush the water from pipes before drawing water for drinking, cooking or making baby formula. The longer water sits in pipes, the more lead it is likely to accumulate. Hot water accumulates lead more quickly than cold water, so be sure to draw cold water for cooking and drinking. To avoid wasting water, save drawn water in a bucket for later use to refill toilet tanks.
- Shower, change and wash clothes promptly after completing tasks where you may be exposed to lead-based products and lead dust. Do not bring lead-contaminated work clothing into a home with a child or pregnant woman.
- Check for recalls of toys and other items that have been found to contain lead. See the Consumer Product Safety Commission website.
Boiling water does not remove lead hazards and may even increase the concentration of lead in the water. However, a variety of methods are available for reducing lead in tap water:36
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image from Erik Gregg at Creative Commons |
- Reverse osmosis filters
- Distillers
- Undersink filters
- Countertop filters
- Faucet filters
These devices come in a variety of designs, prices and operating costs. Care should be taken that a filter is effective at removing lead before purchase, for not all filters are designed to remove lead.
Women who may have experienced lead exposures at any time in their lives should take extra care when pregnant or lactating (breastfeeding) to follow the recommendations for dietary calcium intake. A lack of calcium in a mother's body may accelerate demineralization of her bones and teeth to supply calcium to her fetus or to her milk. If she has lead stored in her bones, demineralizations will mobilize lead into her blood. See our Reproductive Health Research and Resources webpage for more information about dietary guidelines during pregnancy.
Regulation
Lead has been known as a neurotoxicant for almost as long as humans have been using it. In 1922, the League of Nations banned white-lead interior paint based on evidence of harm to children. Although several European countries adopted the ban, the US declined to do so.37 Children and their families in the US will continue to struggle with the legacy of both decisions for decades.
The United States has many various regulatory standards for lead, created through several agencies. Limits on lead levels have been set in drinking water, in paint, in plumbing and in occupational settings. Some states have implemented laws, often stricter than those of the federal government.
As evidence of lead's harm has continued to accrue, the blood lead level in children deemed acceptable by various regulatory agencies has fallen. Scientists now concur that there is no safe level of exposure to lead—any lead exposure is harmful to children.
data from Gilbert & Weiss43 and CDC;44 click to zoom
See more about lead and health in the list of CHE publications and Dig Deeper resources in the right sidebar.
This page was last revised by student intern Eva Bauer and Nancy Hepp in January 2017. Information sourced from Toxipedia is noted with its icon.
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* header image from Holly Hayes at Creative Commons
