Lead poisoning

Classically, "lead poisoning" or "lead intoxication" has been defined as exposure to high levels of lead, typically associated with severe health effects. Poisoning is a pattern of symptoms that occur with toxic effects from mid to high levels of exposure; toxicity is a wider spectrum of effects, including subclinical ones (those that do not cause symptoms). However, professionals often use "lead poisoning" and "lead toxicity" interchangeably, and official sources do not always restrict the use of "lead poisoning" to refer only to symptomatic effects of lead. Diagnosis and treatment of lead exposure are based on blood lead level (the amount of lead in the blood), measured in micrograms of lead per deciliter of blood (μg/dL). Urine lead levels may be used, though less commonly. In cases of chronic exposure, lead often sequesters in the highest concentrations first in the bones, then in the kidneys. If a provider is performing a provocative excretion test, or "chelation challenge", a measurement obtained from urine rather than blood is likely to provide a more accurate representation of total lead burden to a skilled interpreter. The US Centers for Disease Control and Prevention and the World Health Organization state that a blood lead level of 10 μg/dL or above is a cause for concern; however, lead may impair development and have harmful health effects even at lower levels, and there is no known safe exposure level. Authorities such as the American Academy of Pediatrics define lead poisoning as blood lead levels higher than 10 μg/dL. Features of poisoning differ depending on whether the agent is an organic compound (one that contains carbon), or an inorganic one. Organic lead poisoning is now very rare, because countries across the world have phased out the use of organic lead compounds as gasoline additives. These compounds are still used in industrial settings. Organic lead compounds, which cross the skin and respiratory tract easily, affect the central nervous system predominantly. ==Signs and symptoms==

Lead poisoning can cause a variety of symptoms and signs which vary depending on the individual and the duration of lead exposure. Poisoning by organic lead compounds has symptoms predominantly in the central nervous system, such as insomnia, delirium, cognitive deficits, tremor, hallucinations, and convulsions. Early symptoms of lead poisoning in adults are commonly nonspecific and include depression, loss of appetite, intermittent abdominal pain, nausea, diarrhea, constipation, and muscle pain. In adults, symptoms can occur at levels above 40 μg/dL, but are more likely to occur only above 50–60 μg/dL. Anemia may appear at blood lead levels higher than 50 μg/dL. Signs that occur in adults at blood lead levels exceeding 100 μg/dL include wrist drop and foot drop, and signs of encephalopathy (a condition characterized by brain swelling), such as those that accompany increased pressure within the skull, delirium, coma, seizures, and headache. In children, signs of encephalopathy such as bizarre behavior, discoordination, and apathy occur at lead levels exceeding 70 μg/dL. A blue line along the gum with bluish black edging to the teeth, known as a Burton line, is another indication of chronic lead poisoning. Children with chronic poisoning may refuse to play or may have hyperkinetic or aggressive behavior disorders. Effects on children A pregnant woman who has elevated blood lead levels is at greater risk of a premature birth or a low birth weight. Children are more at risk for lead poisoning because their smaller bodies are in a continuous state of growth and development. Young children are much more vulnerable to lead poisoning, as they absorb 4 to 5 times more lead than an adult from a given source. Furthermore, children, especially as they are learning to crawl and walk, are constantly on the floor and therefore more prone to ingesting and inhaling dust that is contaminated with lead. Slow development of normal childhood behaviors, such as talking and use of words, and permanent intellectual disability are both commonly seen. Although less common, fingernails can develop leukonychia striata if exposed to abnormally high lead concentrations. On July 30, 2020, a report by UNICEF and Pure Earth revealed that lead poisoning is affecting children on a "massive and previously unknown scale". According to the report, one in three children, up to 800 million globally, have blood lead levels at or above 5 micrograms per decilitre (μg/dL), which is the commonly accepted threshold beyond which action is required. By organ system Lead affects every one of the body's organ systems, especially the nervous system, but also the bones and teeth, the kidneys, and the cardiovascular, immune, and reproductive systems. as have cataracts. Aside from the developmental effects unique to young children, the health effects experienced by adults are similar to those in children, although the thresholds are generally higher. Kidneys Kidney damage occurs with exposure to high levels of lead, and evidence suggests that lower levels can damage kidneys as well. The toxic effect of lead causes nephropathy and may cause Fanconi syndrome, in which the proximal tubular function of the kidney is impaired. Long-term exposure at levels lower than those that cause lead nephropathy have also been reported as nephrotoxic in patients from developed countries that had chronic kidney disease or were at risk because of hypertension or diabetes mellitus. Lead poisoning inhibits excretion of the waste product urate and causes a predisposition for gout, in which urate builds up. This condition is known as saturnine gout. Cardiovascular system Evidence suggests lead exposure is associated with high blood pressure, and studies have also found connections between lead exposure and coronary heart disease, heart rate variability, and death from stroke, but this evidence is more limited. People who have been exposed to higher concentrations of lead may be at a higher risk for cardiac autonomic dysfunction on days when ozone and fine particles are higher. Reproductive system Lead affects both the male and female reproductive systems. In men, when blood lead levels exceed 40 μg/dL, sperm count is reduced and changes occur in volume of sperm, their motility, and their morphology. A pregnant woman's elevated blood lead level can lead to miscarriage, prematurity, low birth weight, and problems with development during childhood. Nervous system , on MRI. Areas of volume loss are shown in color over a template of a normal brain.|alt=Eight MRI views of a brain in black and white, with yellow, orange, and red areas overlaid in spots mainly toward the front. Lead affects the peripheral nervous system (especially motor nerves) and the central nervous system. Reduced academic performance has been associated with lead exposure even at blood lead levels lower than 5 μg/dL. Blood lead levels below 10 μg/dL have been reported to be associated with lower IQ and behavior problems such as aggression, in proportion with blood lead levels. High blood lead levels in adults are also associated with decreases in cognitive performance and with psychiatric symptoms such as depression and anxiety. It was found in a large group of current and former inorganic lead workers in Korea that blood lead levels in the range of 20–50 μg/dL were correlated with neuro-cognitive defects. Elevated lead levels in children are correlated with higher scores on aggression and delinquency measures. A 2007 paper by the same author claims to show a strong association between preschool blood lead and subsequent crime rate trends over several decades across nine countries. Lead exposure in childhood appears to increase school suspensions and juvenile detention among boys. It is believed that the US ban on lead paint in buildings in the late 1970s, as well as the phaseout of leaded gasoline in the 1970s and 1980s, partially helped contribute to the decline of violent crime in the United States since the early 1990s. ==Exposure routes==

Lead is a common environmental pollutant. Causes of environmental contamination include lead-based paint that is deteriorating (e.g. peeling, chipping, chalking, cracking, damp or damage), renovation, repair or painting activities (disturbing or demolishing painted surfaces generate toxic lead dust ), industrial use of lead, such as found in facilities that process lead-acid batteries or produce lead wire or pipes, metal recycling and foundries, Storage batteries and ammunition are made with the largest amounts of lead consumed in the economy each year, in the US as of 2013. Children living near facilities that process lead, such as lead smelters, have been found to have unusually high blood lead levels. In August 2009, parents rioted in China after lead poisoning was found in nearly 2000 children living near zinc and manganese smelters. Lead exposure can occur from contact with lead in air, household dust, soil, water, and commercial products. Some research has suggested a link between leaded gasoline and crime rates. Man-made lead pollution has been elevated in the air for the past 2000 years. Lead pollution in the air is entirely due to human activity (mining and smelting, as well as in gasoline). Occupational exposure workers are at risk for lead exposure. This worker ladles molten lead into billets in a lead-acid battery recovery facility. In adults, occupational exposure is the main cause of lead poisoning. In addition, lead miners and smelters, plumbers and fitters, auto mechanics, glass manufacturers, construction workers, battery manufacturer and recyclers, firing range workers, and plastic manufacturers are at risk for lead exposure. Lead exposure can also occur with intense use of gun ranges, regardless of whether these ranges are indoor or out. Parents who are exposed to lead in the workplace can bring lead dust home on clothes or skin and expose their children. Food Lead may be found in food when food is grown in soil that is high in lead, airborne lead contaminates the crops, animals eat lead in their diet, or lead enters the food either from what it was stored or cooked in. Ingestion of lead paint and batteries is also a route of exposure for livestock, which can subsequently affect humans. Milk produced by contaminated cattle can be diluted to a lower lead concentration and sold for consumption. In Bangladesh, lead chromate has been added to turmeric to make it more yellow. This is believed to have started in the 1980s. Following a 2019 report identifying adulterated turmeric as the main cause of lead poisoning in Bangladesh, the government began a rapid crackdown and public service campaign on it. By 2021, leaded turmeric had vanished from the Bangladeshi market, and blood lead levels in workers at turmeric mills had dropped by a median of 30%. In Hong Kong, the maximum allowed lead parts per million is 6 in solid foods and 1 in liquid foods. In December 2022, 28 dark chocolate brands were tested by Consumer Reports, which found that 23 of them contained cadmium, lead or both. When cocoa beans are set outside near polluting industrial plants, they can be contaminated by dust containing lead. The Centers for Disease Control publishes conversion factors that relate blood lead levels to dietary lead, yielding interim reference levels (IRLs) for daily consumption of lead in food. As of 2021, CDC's blood lead reference value (BLRV) is 3.5 μg/dL. For all children, the conversion factor is 0.16 μg/dL per μg Pb per day yielding an IRL of 2.2 μg/day. For females of childbearing age, the numbers are 0.04 and 8.8, respectively. No other groups are defined. By comparison, California's No Significant Risk Levels (NSRLs) for carcinogens and Maximum Allowable Dose Levels (MADLs) are 15 and 0.5 μg/day, respectively. Paint Some lead compounds are colorful and are used widely in paints, and lead paint is a major route of lead exposure in children. A study conducted in 1998–2000 found that 38 million housing units in the US had lead-based paint, down from a 1990 estimate of 64 million. Deteriorating lead paint can produce dangerous lead levels in household dust and soil. Deteriorating lead paint and lead-containing household dust are the main causes of chronic lead poisoning. In oil painting, it was once common for colours such as yellow or white to be made with lead carbonate. Lead white oil colour was the main white of oil painters until superseded by compounds containing zinc or titanium in the mid-20th century. It is speculated that the painter Caravaggio and possibly Francisco Goya and Vincent Van Gogh had lead poisoning due to overexposure or carelessness when handling this colour. Soil , which used to be added to automotive gasoline (and still is added to some aviation gasolines), contributed to soil contamination.|alt=a closeup of a red gasoline pump with a warning label that reads, "for use as a motor fuel only" (in larger writing) "contains lead" (in smaller writing) "(tetraethyl)" Residual lead in soil contributes to lead exposure in urban areas. Lead content in soil may be caused by broken-down lead paint, residues from lead-containing gasoline, used engine oil, tire weights, or pesticides used in the past, contaminated landfills, or from nearby industries such as foundries or smelters. Although leaded soil is less of a problem in countries that no longer have leaded gasoline, it remains prevalent, raising concerns about the safety of urban agriculture; eating food grown in contaminated soil can present a lead hazard. Interfacial solar evaporation has been recently studied as a technique for remediating lead-contaminated sites, which involves the evaporation of heavy metal ions from moist soil. Water Lead from the atmosphere or soil can end up in groundwater and surface water. It is also potentially in drinking water, e.g. from plumbing and fixtures that are either made of lead or have lead solder. Since acidic water breaks down lead in plumbing more readily, chemicals can be added to municipal water to increase the pH and thus reduce the corrosivity of the public water supply. In 2004, a team of seven reporters from The Washington Post discovered high levels of lead in the drinking water in Washington, DC, and won an award for investigative reporting for a series of articles about this contamination. In the water crisis in Flint, Michigan, a switch to a more corrosive municipal water source caused elevated lead levels in domestic tap water. Like Flint, Michigan, and Washington, D.C., a similar situation affects the state of Wisconsin, where estimates call for replacement of up to 176,000 underground pipes made of lead known as lead service lines. The City of Madison, Wisconsin addressed the issue and replaced all of their lead service lines, but there are still other cities that have yet to follow suit. While there are chemical methods that could help reduce the amount of lead in the water distributed, a permanent fix would be to replace the pipes completely. While the state may replace the pipes below ground, homeowners must replace the pipes on their property, at an average cost of $3,000. Experts say that if the city were to replace their pipes and the citizens were to keep the old pipes located within their homes, there would be a potential for more lead to dissolve into their drinking water. Collected rainwater from roof runoff used as potable water may contain lead if there are lead contaminants on the roof or in the storage tank. Lead wheel weights have been found to accumulate on roads and interstates and erode in traffic, entering the water runoff through drains. Leaded fishing weights accumulate in rivers, streams, ponds, and lakes. Gasoline Tetraethyllead was first added to gasoline in 1923, as it helped prevent engine knocking. Automotive exhaust represented a major way for lead to be inhaled, invade the bloodstream, and pass into the brain. The use of lead in gasoline peaked in the 1970s. By the next decade, most high-income countries prohibited the use of leaded petrol. As late as 2002, almost all low- and middle-income countries, including some OECD members, still used it. The UN Environment Programme (UNEP) thus launched a campaign in 2002 to eliminate its use, leading to Algeria being the last country to stop its use in July 2021. Lead-containing products Lead can be found in products such as kohl, an ancient cosmetic from the Middle East, South Asia, and parts of Africa that has many other names, and in some toys. Vinyl mini-blinds, found especially in older housing, may contain lead. Ingestion of metallic lead, such as small lead fishing lures, increases blood lead levels and can be fatal. Ingestion of lead-contaminated food is also a threat. Ceramic glaze often contains lead, and dishes that have been improperly fired can leach the metal into food, potentially causing severe poisoning. Bullets lodged in the human body rarely cause significant levels of lead, but bullets lodged in the joints are the exception, as they deteriorate and release lead into the body over time. In May 2015, Indian food safety regulators in the state of Uttar Pradesh found that samples of Maggi 2 Minute Noodles contained lead up to 17 times beyond permissible limits. On 3 June 2015, the New Delhi Government banned the sale of Maggi noodles in New Delhi stores for 15 days because it was found to contain lead beyond the permissible limit. The Gujarat FDA on 4 June 2015 banned the noodles for 30 days after 27 out of 39 samples were detected with objectionable levels of metallic lead, among other things. Some of India's biggest retailers like Future Group, Big Bazaar, Easyday, and Nilgiris have imposed a nationwide ban on Maggi noodles. Many other states too have banned Maggi noodles. Bullets Contact with ammunition is a source of lead exposure. As of 2013, lead-based ammunition production is the second largest annual use of lead in the US, accounting for over 84,800 metric tons in 2013, The Environmental Protection Agency (EPA) cannot regulate cartridges and shells, as a matter of law. Lead birdshot is banned in some areas, but this is primarily for the benefit of the birds and their predators, rather than humans. Contamination from heavily used gun ranges is of concern to those who live near by. Non-lead alternatives include copper, zinc, steel, tungsten-nickel-iron, bismuth-tin, and polymer blends such as tungsten-polymer and copper-polymer. Because game animals can be shot using lead bullets, the potential for lead ingestion from game meat consumption has been studied clinically and epidemiologically. In a study conducted by the CDC in 2009, a cohort from North Dakota was enrolled and asked to self-report historical consumption of game meat, and participation in other activities that could cause lead exposure. The study found that participants' age, sex, housing age, current hobbies with potential for lead exposure, and game consumption were all associated with blood lead level (PbB). According to a study published in 2008, 1.1% of the 736 persons consuming wild game meat tested had PbB ≥5 μg/dL In November 2015 the US Health and Human Services (HHS), Centers for Disease Control and Prevention (CDC), and National Institute for Occupational Safety and Health (NIOSH) designated 5 μg/dL (five micrograms per deciliter) of whole blood, in a venous blood sample, as the reference blood lead level for adults. An elevated blood lead level (BLL) is defined as a BLL ≥5 μg/dL. This case definition is used by the Adult Blood Lead Epidemiology and Surveillance (ABLES) program, the Council of State and Territorial Epidemiologists (CSTE), and the CDC's National Notifiable Diseases Surveillance System (NNDSS). Previously (i.e., from 2009 until November 2015), the case definition for an elevated BLL was a BLL ≥10 μg/dL. Cannabis In 2007, a mass poisoning due to adulterated marijuana was uncovered in Leipzig, Germany, where 29 young adults were hospitalized with lead poisoning for several months after having smoked marijuana that had been tainted with small lead particles. One hypothesis from the police was that lead, with its high specific gravity, was used to increase the weight of street marijuana sold by the gram, thereby maximizing the dealers' profits. The researchers estimated that the profit per kilogram increased by as much as $1,500 with the lead added. It is common for drugs to be cut with less-expensive substances to increase the profits of dealers or distributors (e.g., cocaine is routinely adulterated with sugars, talcum powder, magnesium salts, and even other drugs). It is thought that the adverse reactions to many of these drugs are a result of poor manufacturing rather than face-value overdoses. Besides adulteration, cannabis plants have an inherent ability to absorb heavy metals from the soil. This makes them useful for remediating contaminated sites. But this may also make cannabis dangerous for consumers who ingest it. Some cannabis strains have been bred specifically to remove pollutants from soil, air, or water, a method known as phytoremediation. In 2022, around 40% of cannabis products sold at unlicensed storefronts in New York City were found to contain heavy metals (e.g., lead, nickel), pesticides, and bacteria. ==Toxicokinetics==

, still used as an additive in some fuels, can be absorbed through the skin. are also absorbed through skin. The main sources of absorption of inorganic lead are from ingestion and inhalation. In adults, about 35–40% of inhaled lead dust is deposited in the lungs, and about 95% of that goes into the bloodstream. The main body tissues that store lead are the blood, soft tissues, and bone; the half-life of lead in these tissues is measured in weeks for blood, months for soft tissues, and years for bone. In adults, 94% of absorbed lead is deposited in the bones and teeth, but children only store 70% in this manner, a fact which may partially account for the more serious health effects on children. The half-life of lead in the blood in men is about 40 days, but it may be longer in children and pregnant women, whose bones are undergoing remodeling, which allows the lead to be continuously re-introduced into the bloodstream. Lead is removed from the body very slowly, mainly through urine. Smaller amounts of lead are also eliminated through the feces, and very small amounts in hair, nails, and sweat. ==Toxicodynamics==

Toxicodynamics describes how the toxin affects the body, including the mechanisms causing its symptoms. Lead has no known physiologically necessary role in the body, and its harmful effects are myriad. Lead and other heavy metals create reactive radicals which damage cell structures, including DNA and cell membranes. Lead also interferes with DNA transcription, enzymes that help in the synthesis of vitamin D, and enzymes that maintain the integrity of the cell membrane. Lead interferes with metabolism of bones and teeth Lead exposure has also been associated with a decrease in activity of immune cells such as polymorphonuclear leukocytes. The lead ion has a lone pair in its electronic structure, which can result in a distortion in the coordination of ligands, and in 2007 was hypothesized to be important in lead poisoning's effects on enzymes (see ). One of the main causes for the pathology of lead is that it interferes with the activity of an essential enzyme called delta-aminolevulinic acid dehydratase, or ALAD (see image of the enzyme structure), which is important in the biosynthesis of heme, the cofactor found in hemoglobin. Lead also inhibits the enzyme ferrochelatase, another enzyme involved in the formation of heme. Ferrochelatase catalyzes the joining of protoporphyrin and Fe2+ to form heme. Another effect of lead's interference with heme synthesis is the buildup of heme precursors, such as aminolevulinic acid, which may be directly or indirectly harmful to neurons. Neurons , a part of the brain involved in memory. Hippocampi of lead-exposed rats (bottom) show structural damage such as irregular nuclei (IN) and denaturation of myelin (DMS) compared to controls (top). Lead poisoning interferes with the normal development of a child's brain and nervous system; therefore children are at greater risk of lead neurotoxicity than adults are. In a child's developing brain, lead interferes with synapse formation in the cerebral cortex, neurochemical development (including that of neurotransmitters), and organization of ion channels. The targeting of NMDA receptors is thought to be one of the main causes for lead's toxicity to neurons. ==Diagnosis==

Diagnosis includes determining the clinical signs and the medical history, with inquiry into possible routes of exposure. Clinical toxicologists, medical specialists in the area of poisoning, may be involved in diagnosis and treatment. The main tool in diagnosing and assessing the severity of lead poisoning is laboratory analysis of the blood lead level (BLL). (arrows) of red blood cells in a 53-year-old who had elevated blood lead levels due to drinking repeatedly from glasses decorated with lead paint.|alt=dozens of pink circular bodies with white centers on a white background. Arrows point to three of the cells; two are speckled with dark purple dots, and the third has an irregular outer border Blood film examination may reveal basophilic stippling of red blood cells (dots in red blood cells visible through a microscope), as well as the changes normally associated with iron-deficiency anemia (microcytosis and hypochromasia). However, basophilic stippling is also seen in unrelated conditions, such as megaloblastic anemia caused by vitamin B12 (cobalamin) and folate deficiencies. Contrary to other sideroblastic anemias, there are no ring sideroblasts in a bone marrow smear. Exposure to lead can also be evaluated by measuring erythrocyte protoporphyrin (EP) in blood samples. Blood lead levels are an indicator mainly of recent or current lead exposure, not of total body burden. Lead in bones can be measured noninvasively by X-ray fluorescence; this may be the best measure of cumulative exposure and total body burden. These lead lines, caused by increased calcification due to disrupted metabolism in the growing bones, become wider as the duration of lead exposure increases. Lead poisoning shares symptoms with other conditions and may be easily missed. Previous to 2012, the value for children was 10 (μg/dL). Lead-exposed workers in the US are required to be removed from work when their level is greater than 50 μg/dL if they do construction and otherwise greater than 60 μg/dL. In 2015, the US Health and Human Services (HHS), Centers for Disease Control and Prevention (CDC), and National Institute for Occupational Safety and Health (NIOSH) designated 5 μg/dL (five micrograms per deciliter) of whole blood, in a venous blood sample, as the reference blood lead level for adults. An elevated blood lead level (BLL) is defined as a BLL ≥5 μg/dL. This case definition is used by the Adult Blood Lead Epidemiology and Surveillance (ABLES) program, the Council of State and Territorial Epidemiologists (CSTE), and the CDC's National Notifiable Diseases Surveillance System (NNDSS). Previously (i.e., from 2009 until November 2015), the case definition for an elevated BLL was a BLL ≥10 μg/dL. The US national BLL geometric mean among adults was 1.2 μg/dL in 2009–2010. Blood lead concentrations in poisoning victims have ranged from 30 to 80 μg/dL in children exposed to lead paint in older houses, 77–104 μg/dL in persons working with pottery glazes, 90–137 μg/dL in individuals consuming contaminated herbal medicines, 109–139 μg/dL in indoor shooting range instructors and as high as 330 μg/dL in those drinking fruit juices from glazed earthenware containers. ==Prevention==

Prevention for lead poisoning can be divided into primary, secondary, and tertiary prevention methods. Primary prevention Primary prevention of lead poisoning aims to address the root cause of the problem before any adverse health outcomes occur. This can be achieved through an attempt to remove the sources of lead poisoning (either by government, corporations, or individuals) or by educating individuals and communities about lead exposure, its sources, and its health impacts which can help prevent lead poisoning from happening in the first place. Lead pipe replacement Lead pipe replacement is one of the most effective ways to reduce lead in water, as lead service lines are the leading drinking water contamination source. Replacement of lead service lines has been shown to drastically reduce lead levels in water. When considering lead line replacement as a primary prevention method, it is essential to specify the need for complete replacement versus partial replacement as partial replacement of lead service lines can disturb/dislodge lead in unreplaced portions of the pipe, leading to increased concentrations of lead in water. Education The education of workers on lead, its danger, and how its workplace exposure can be decreased, especially when initial blood lead level and urine lead level are high, could help reduce the risk of lead poisoning in the workplace. Testing kit accuracy depends on the user testing all layers of paint and the quality of the kit; the US Environmental Protection Agency (EPA) only approves kits with an accuracy rating of at least 95%. Professional lead testing companies caution that DIY test kits can create health risks for users who do not understand their limitations and liability issues for employers concerning worker protection. As hot water is more likely than cold water to contain higher amounts of lead, only cold water from the tap should be used for drinking, cooking, and making baby formula. Since most of the lead in household water usually comes from plumbing in the house and not from the local water supply, using cold water can avoid lead exposure. Measures such as dust control and household education do not appear to be effective in changing children's blood levels. Prevention measures also exist on the national and municipal levels. Recommendations by health professionals for lowering childhood exposures include banning the use of lead where it is not essential and strengthening regulations that limit the amount of lead in soil, water, air, household dust, and products. The European Union's Restriction of Hazardous Substances Directive limits amounts of lead and other toxic substances in electronics and electrical equipment. In some places, remediation programs exist to reduce the presence of lead when it is found to be high, for example, in drinking water. Removing lead from airplane fuel would prevent approximately 450 tons of lead from being released into the environment every year. Secondary prevention Secondary prevention of lead poisoning seeks to detect early exposures in individuals and intervene to prevent progression and long-term health complications. Screening Screening may be an important method of prevention for those at high risk, The American College of Obstetricians and Gynecologists (ACOG) and American Academy of Pediatrics (AAP), however, recommend asking about risk factors and testing those who have them. Tertiary prevention Tertiary prevention methods focus on treatment, mitigation of symptoms, and improving quality of life in individuals who have already been affected by lead poisoning. These treatment methods are explored in the following section. ==Treatment==

The mainstays of treatment are removal from the source of lead and, for people who have significantly high blood lead levels or who have symptoms of poisoning, chelation therapy. Treatment of iron, calcium, and zinc deficiencies, which are associated with increased lead absorption, is another part of treatment for lead poisoning. When lead-containing materials are present in the gastrointestinal tract (as evidenced by abdominal X-rays), whole bowel irrigation, cathartics, endoscopy, or even surgical removal may be used to eliminate it from the gut and prevent further exposure. Lead-containing bullets and shrapnel may also present a threat of further exposure and may need to be surgically removed if they are in or near fluid-filled or synovial spaces. If lead encephalopathy is present, anticonvulsants may be given to control seizures, and treatments to control swelling of the brain include corticosteroids and mannitol. Treatment of organic lead poisoning involves removing the lead compound from the skin, preventing further exposure, treating seizures, and possibly chelation therapy for people with high blood lead concentrations. Before the advent of organic chelating agents, salts of iodide were given orally, such as heavily popularized by Louis Melsens and many nineteenth- and early twentieth-century doctors. , binds a heavy metal, sequestering it.|alt=a chemical diagram of [CH2N(CH2CO2-)2]2 (shown in black) with the four O-tails binding a metal ion (shown in red). A chelating agent is a molecule with at least two negatively charged groups that allow it to form complexes with metal ions with multiple positive charges, such as lead. The chelate that is thus formed is nontoxic The chelating agents used for treatment of lead poisoning are edetate disodium calcium (CaNa2EDTA), dimercaprol (BAL), which are injected, and succimer and d-penicillamine, which are administered orally. Chelation therapy is used in cases of acute lead poisoning, severe poisoning, and encephalopathy, Chelation therapy is usually stopped when symptoms resolve or when blood lead levels return to premorbid levels. Dimercaprol used alone may also redistribute lead to the brain and testes. Chelating agents taken orally can increase the body's absorption of lead through the intestine. Chelation challenge mainly measures the burden of lead in soft tissues, though whether it accurately reflects long-term exposure or the amount of lead stored in bone remains controversial. Although the technique has been used to determine whether chelation therapy is indicated and to diagnose heavy metal exposure, some evidence does not support these uses as blood levels after chelation are not comparable to the reference range typically used to diagnose heavy metal poisoning. The single chelation dose could also redistribute the heavy metals to more sensitive areas such as central nervous system tissue. ==Epidemiology==

Since lead has been used widely for centuries, the effects of exposure are worldwide. Environmental lead is ubiquitous, and everyone has some measurable blood lead level. Lead is one of the largest environmental medicine problems in terms of numbers of people exposed and the public health toll it takes. Despite this, it is estimated that efforts to prevent lead exposure receive only approximately $0.31 of funding per year of healthy life impacted - some six hundred times less than the equivalent funding for HIV. Although regulation reducing lead in products has greatly reduced exposure in the developed world since the 1970s, lead is still allowed in products in many developing countries. Significant disparities exist in the enactment of bans, with regions such as the Middle East, North Africa, and Sub-Saharan Africa currently the most likely to have countries lacking such measures. Despite a phase-out in many parts of the Global North, Global South exposure has increased by nearly three times. In all countries that have banned leaded gasoline, average blood lead levels have fallen sharply. Poor children in developing countries are at especially high risk for lead poisoning. Of North American children, 7% have blood lead levels above 10 μg/dL, whereas among Central and South American children, the percentage is 33–34%. African-American children and those living in old housing have also been found to be at elevated risk for high blood lead levels in the US. Low-income people often live in old housing with lead paint, which may begin to peel, exposing residents to high levels of lead-containing dust. Risk factors for elevated lead exposure include alcohol consumption and smoking (possibly because of contamination of tobacco leaves with lead-containing pesticides). Children may also have a higher intake of lead than adults; they breathe faster and may be more likely to have contact with and ingest soil. Notable cases Cases of mass lead poisoning can occur. In 2009, 15,000 people were planned to be relocated from Jiyuan in central Henan province to other locations after 1000 children living around China's largest smelter plant (owned and operated by Yuguang Gold and Lead) were found to have excess lead in their blood. The total cost of this project is estimated to around 1 billion yuan ($150 million). 70% of the cost was estimated to be paid by the local government and the smelter company, while the rest would be paid by the residents themselves. The government suspended production at 32 of 35 lead plants. The affected area includes people from 10 different villages. The Zamfara State lead poisoning epidemic occurred in Nigeria in 2010. As of 5 October 2010, at least 400 children have died from the effects of lead poisoning. Sex-specific susceptibility Neuroanatomical pathology due to lead exposure is more pronounced in males, suggesting that lead-related toxicity has a disparate impact across sexes. ==Prognosis==

Reversibility The outcome is related to the extent and duration of lead exposure. Effects of lead on the physiology of the kidneys and blood are generally reversible; its effects on the central nervous system are not. Children with lead poisoning may thus have adverse health, cognitive, and behavioral effects that follow them into adulthood. Encephalopathy Lead encephalopathy is a medical emergency and causes permanent brain damage in 70–80% of children affected by it, even those that receive the best treatment. Long-term Exposure to lead may also decrease lifespan and have health effects in the long term. Evidence also suggests that age-related mental decline and psychiatric symptoms are correlated with lead exposure. Some health effects, such as high blood pressure, are only significant risks when lead exposure is prolonged (over about one year). Furthermore, the neurological effects of lead exposure are exacerbated and long-lasting in low-income children in comparison to those of higher economic standing. This does not imply that being wealthy can prevent lead from causing long-term mental health issues. == Violence ==

Lead poisoning in children has been linked to changes in brain function that can result in low IQ and increased impulsivity and aggression. These traits of childhood lead exposure are associated with crimes of passion, such as aggravated assault in young adults. An increase in lead exposure in children was linked to an increase in aggravated assault rates 22 years later. For instance, the peak in leaded gasoline use in the late 1970s correlates with a peak in aggravated assault rates in the late 1990s in urban areas across the United States. ==History==

noted lead's effect on the mind in the first century AD.|alt=an ancient Greek black-and-white woodcut print of a middle-aged bearded man. His left hand rests on a book, and in his right hand he holds a plant. Lead poisoning was among the first known and most widely studied work-related environmental hazards. Lead was used extensively in Roman aqueducts from about 500 BC to 300 AD. Gout, prevalent in affluent Rome, is thought to be the result of lead, or leaded eating and drinking vessels. Sugar of lead (lead(II) acetate) was used to sweeten wine, and the gout that resulted from this was known as "saturnine" gout. It is even hypothesized that lead poisoning may have contributed to the decline of the Roman Empire, The use of leaden cookware, though popular, was not the general standard and copper cookware was used far more generally. There is also no indication how often was added or in what quantity. In 1983, environmental chemist Jerome Nriagu argued in a milestone paper that Roman civilization collapsed as a result of lead poisoning. Clair Patterson, the scientist who convinced governments to ban lead from gasoline, enthusiastically endorsed this idea, which nevertheless triggered a volley of publications aimed at refuting it. In 1984, John Scarborough, a pharmacologist and classicist, criticized the conclusions drawn by Nriagu's book as "so full of false evidence, miscitations, typographical errors, and a blatant flippancy regarding primary sources that the reader cannot trust the basic arguments." Although today lead is no longer seen as the prime culprit of Rome's demise, its status in the system of water distribution by lead pipes () still stands as a major public health issue. By measuring Pb isotope compositions of sediments from the Tiber River and the Trajanic Harbor, the present work shows that "tap water" from ancient Rome had 100 times more lead than local spring waters. A study published in January 2025 concluded that lead pollution peaked during a prosperous period known as the Pax Romana, adding credence to the theory that lead pollution have contributed to the decline of the Roman Empire. After antiquity, mention of lead poisoning was absent from medical literature until the end of the Middle Ages. In 1656 the German physician Samuel Stockhausen recognized dust and fumes containing lead compounds as the cause of disease, called since ancient Roman times , that were known to afflict miners, smelter workers, potters, and others whose work exposed them to the metal. The painter Caravaggio might have died of lead poisoning. Bones with high lead levels were recently found in a grave thought likely to be his. Paints used at the time contained high amounts of lead salts. Caravaggio is known to have exhibited violent behavior, a symptom commonly associated with lead poisoning. In 17th-century Germany, the physician Eberhard Gockel discovered lead-contaminated wine to be the cause of an epidemic of colic. In the 18th century lead poisoning was fairly frequent on account of the widespread drinking of rum, which was made in stills with a lead component (the "worm"). It was a significant cause of mortality amongst slaves and sailors in the colonial West Indies. Lead poisoning from rum was also noted in Boston. Benjamin Franklin suspected lead to be a risk in 1786. Also in the 18th century, "Devonshire colic" was the name given to the symptoms experienced by people of Devon who drank cider made in presses that were lined with lead. et Augusta Dejerine-Klumpke (Sorbonne Université). With the Industrial Revolution in the 19th century, lead poisoning became common in the work setting. William James Furnival (1853–1928), research ceramist of City & Guilds London Institute, appeared before Parliament in 1901 and presented a decade's evidence to convince the nation's leaders to remove lead completely from the British ceramic industry. His 852-page treatise, Leadless Decorative Tiles, Faience, and Mosaic of 1904, published that campaign and provided recipes to promote lead-free ceramics. At the request of the Illinois state government in the US, Alice Hamilton (1869–1970) documented lead toxicity in Illinois industry and in 1911 presented results to the 23rd Annual Meeting of the American Economic Association. Hamilton was a founder of the field of occupational safety and health and published the first edition of her manual, Industrial Toxicology, in 1934, yet in print in revised forms. An important step in the understanding of childhood lead poisoning occurred when toxicity in children from lead paint was recognized in Australia in 1897. Beginning in the 1920s, lead was added to gasoline to improve its combustion; lead from this exhaust persists today in soil and dust in buildings. Blood lead levels worldwide have been declining sharply since the 1980s, when leaded gasoline began to be phased out. The levels found today in most people are orders of magnitude greater than those of pre-industrial society. Due to reductions of lead in products and the workplace, acute lead poisoning is rare in most countries today, but low-level lead exposure is still common. It was not until the second half of the 20th century that subclinical lead exposure became understood to be a problem. Blood lead levels once considered safe are now considered hazardous, with no known safe threshold. In the late 1950s through the 1970s Herbert Needleman and Clair Cameron Patterson did research trying to prove lead's toxicity to humans. In the 1980s Needleman was falsely accused of scientific misconduct by lead industry associates. In 2002 Tommy Thompson, United States Secretary of Health and Human Services, appointed at least two persons with conflicts of interest to the CDC's Lead Advisory Committee. In 2014, a case by the State of California against several companies decided against Sherwin-Williams, NL Industries, and ConAgra and ordered them to pay $1.15 billion. The disposition of The People v. ConAgra Grocery Products Company et al. in the California 6th Appellate District Court on 14 November 2017 is that: On 6 December 2017, the petitions for rehearing from NL Industries, Inc., ConAgra Grocery Products Company, and The Sherwin-Williams Company were denied. in the United States, lead paint in rental housing remains a hazard to children. Both landlords and insurance companies have adopted strategies that limit the chance of recovery for damages due to lead poisoning: insurance companies by excluding coverage for lead poisoning from policies, and landlords by crafting barriers to the collection of any monetary damages compensating plaintiffs for damage. ==Other species==

Humans are not alone in suffering from lead's effects; plants and animals are also affected by lead toxicity to varying degrees depending on species. and to provide information on the pathophysiology of lead, such as how it is absorbed and distributed in the body. Farm animals such as cows and horses as well as pet animals are also susceptible to the effects of lead toxicity. When hunters use lead shot, waterfowl such as ducks can ingest the spent pellets later and be poisoned; predators that eat these birds are also at risk. Lead shot-related waterfowl poisonings were first documented in the US in the 1880s. Lead shot has been banned for hunting waterfowl in several countries, including the US in 1991 and Canada in 1997. Other threats to wildlife include lead paint, sediment from lead mines and smelters, and lead weights from fishing lines. Among condors around the Grand Canyon, lead poisoning due to eating lead shot is the most frequently diagnosed cause of death. ==See also==