Symptoms of<unk> <unk>  can cause a variety of symptoms and signs which vary depending on the individual and the duration of<unk>  exposure. Symptoms are nonspecific and may be subtle, and someone with elevated<unk>  levels may have no symptoms. Symptoms usually develop over weeks to months as<unk>  builds up in the body during a chronic exposure, but acute symptoms from brief, intense exposures also occur. Symptoms from exposure to organic<unk> , which is probably more toxic than inorganic<unk>  due to its lipid solubility, occur rapidly.<unk>  by organic<unk>  compounds has symptoms predominantly in the central nervous system, such as insomnia, delirium, cognitive deficits, tremor, hallucinations, and convulsions. Symptoms may be different in adults and children; the main symptoms in adults are headache, abdominal pain, memory loss, kidney failure, male reproductive problems, and weakness, pain, or tingling in the extremities. Early symptoms of<unk>  in adults are commonly nonspecific and include depression, loss of appetite, intermittent abdominal pain, nausea, diarrhea, constipation, and muscle pain. Other early signs in adults include malaise, fatigue, decreased libido, and problems with sleep. An unusual taste in the mouth and personality changes are also early signs. In adults, symptoms can occur at levels above 40 μg/dL, but are more likely to occur only above 50–60 μg/dL. Symptoms begin to appear in children generally at around 60 μg/dL. However, the<unk>  levels at which symptoms appear vary widely depending on unknown characteristics of each individual. At blood<unk>  levels between 25 and 60 μg/dL, neuropsychiatric effects such as delayed reaction times, irritability, and difficulty concentrating, as well as slowed motor nerve conduction and headache can occur. Anemia may appear at blood<unk>  levels higher than 50 μg/dL. In adults, abdominal colic, involving paroxysms of pain, may appear at blood<unk>  levels greater than 80 μg/dL. Signs that occur in adults at blood<unk>  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<unk>  levels exceeding 70 μg/dL. For both adults and children, it is rare to be asymptomatic if blood<unk>  levels exceed 100 μg/dL. Acute<unk>  In acute<unk> , typical neurological signs are pain, muscle weakness, numbness and tingling, and, rarely, symptoms associated with inflammation of the brain. Abdominal pain, nausea, vomiting, diarrhea, and constipation are other acute symptoms.<unk> 's effects on the mouth include astringency and a metallic taste. Gastrointestinal problems, such as constipation, diarrhea, poor appetite, or weight loss, are common in acute<unk> . Absorption of large amounts of<unk>  over a short time can cause shock (insufficient fluid in the circulatory system) due to loss of water from the gastrointestinal tract. Hemolysis (the rupture of red blood cells) due to acute<unk>  can cause anemia and hemoglobin in the urine. Damage to kidneys can cause changes in urination such as acquired fanconi syndrome and decreased urine output. People who survive acute<unk>  often go on to display symptoms of chronic<unk> . Chronic<unk>  Chronic<unk>  usually presents with symptoms affecting multiple systems, but is associated with three main types of symptoms: gastrointestinal, neuromuscular, and neurological. Central nervous system and neuromuscular symptoms usually result from intense exposure, while gastrointestinal symptoms usually result from exposure over longer periods. Signs of chronic exposure include loss of short-term memory or concentration, depression, nausea, abdominal pain, loss of coordination, and numbness and tingling in the extremities. Fatigue, problems with sleep, headaches, stupor, slurred speech, and anemia are also found in chronic<unk> . A "lead hue" of the skin with pallor and/or lividity is another feature. A blue line along the gum with bluish black edging to the teeth, known as a Burton line, is another indication of chronic<unk> . Children with chronic<unk>  may refuse to play or may have hyperkinetic or aggressive behavior disorders. Visual disturbance may present with gradually progressing blurred vision as a result of central scotoma, caused by toxic optic neuritis. Effects on children As<unk>  safety standards become more stringent, fewer children in the US are found to have elevated<unk>  levels. A pregnant woman who has elevated blood<unk>  levels is at greater risk of a premature birth or with a low birth weight. Children are more at risk for<unk>  because their smaller bodies are in a continuous state of growth and development. Young children are much more vulnerable to<unk> , as they absorb 4 to 5 times more<unk>  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<unk> . The classic signs and symptoms in children are loss of appetite, abdominal pain, vomiting, weight loss, constipation, anemia, kidney failure, irritability, lethargy, learning disabilities, and behavioral problems. Slow development of normal childhood behaviors, such as talking and use of words, and permanent intellectual disability are both commonly seen. Although less common, it is possible for fingernails to develop leukonychia striata if exposed to abnormally high<unk>  concentrations. On July 30, 2020, a report by UNICEF and Pure Earth revealed that<unk>  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<unk>  levels at, or above, 5 micrograms per decilitre (µg/dL), the amount at which action is required. By organ system<unk>  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. Hearing loss and tooth decay have been linked to<unk>  exposure, as have cataracts. Intrauterine and neonatal<unk>  exposure promote tooth decay. 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<unk> , and evidence suggests that lower levels can damage kidneys as well. The toxic effect of<unk>  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<unk>  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.<unk>  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<unk>  exposure is associated with high blood pressure, and studies have also found connections between<unk>  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<unk>  may be at a higher risk for cardiac autonomic dysfunction on days when ozone and fine particles are higher. Reproductive system<unk>  affects both the male and female reproductive systems. In men, when blood<unk>  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<unk>  level can<unk>  to miscarriage, prematurity, low birth weight, and problems with development during childhood.<unk>  is able to pass through the placenta and into breast milk, and blood<unk>  levels in mothers and infants are usually similar. A fetus may be poisoned in utero if<unk>  from the mother's bones is subsequently mobilized by the changes in metabolism due to pregnancy; increased calcium intake in pregnancy may help mitigate this phenomenon. Nervous system The brains of adults who were exposed to<unk>  as children show decreased volume, especially in the prefrontal cortex, 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.<unk>  affects the peripheral nervous system (especially motor nerves) and the central nervous system. Peripheral nervous system effects are more prominent in adults and central nervous system effects are more prominent in children.<unk>  causes the axons of nerve cells to degenerate and lose their myelin coats.<unk>  exposure in young children has been linked to learning disabilities, and children with blood<unk>  concentrations greater than 10 μg/dL are in danger of developmental disabilities. Increased blood<unk>  level in children has been correlated with decreases in intelligence, nonverbal reasoning, short-term memory, attention, reading and arithmetic ability, fine motor skills, emotional regulation, and social engagement. The effect of<unk>  on children's cognitive abilities takes place at very low levels. There is apparently no lower threshold to the dose-response relationship (unlike other heavy metals such as mercury). Reduced academic performance
Lead poisoning
Anxiety disorder
Mercury poisoning
Iron-deficiency anemia
Zinc toxicity
Malabsorption
Iron poisoning
Polyneuropathy