Lead poisoning in children still presents as a significant issue worldwide, with the main mode of exposure being chips and dust from lead-based paint. CNS impairment is the most prominent and causes a variety of symptoms depending on the severity of exposure. The diagnosis is made by confirming increased levels of lead in blood or urine, while treatment principles rely on cessation of exposure, parent education and chelation therapy in severe cases.
Lead poisoning in children primarily manifests with central nervous system symptoms. In acute poisoning, altered consciousness, encephalopathy, seizures and coma are most common symptoms. On the other hand, prolonged exposure to somewhat smaller concentrations manifests as cognitive impairment and various intellectual disabilities that may often become permanent . Reduction in IQ, reading difficulties and irritability are observed in children, while aggressive behavior and delinquency have shown to occur in later life, especially in the setting of accumulated lead in the skeletal system . Nonspecific symptoms include a headache, nausea, abdominal pain, loss of appetite and somnolence . Together with central nervous system involvement, renal failure, hypertension and anemia may also develop .
To make the diagnosis of lead poisoning, a strong clinical suspicion is needed. Patient history may be the single most important tool in making a preliminary diagnosis. Living or regularly visiting houses that are built before 1950, or houses in which major renovations are ongoing, together with data that may indicate some friend or relative is suffering from similar symptoms are vital in differentiating lead poisoning from other potential causes . To confirm the diagnosis, laboratory and imaging studies need to be conducted. Firstly, a complete blood count together with serum electrolytes, kidney function parameters and whole-blood levels of lead should be performed. Capillary blood testing for lead is a useful tool in selecting patients in which whole-blood levels need to be measured. Imaging studies such as plain radiography of the abdomen may reveal ingested particles of lead that are radiopaque, while X-ray of long bones may reveal intense calcification zones. Depending on the levels of lead in the circulation, appropriate treatment strategies are implemented.
Therapeutic strategies depend on the confirmed levels of lead and firstly include cessation of exposure and education of children and parents. When concentrations are between 10-14 µg/dL, a regular 3-month follow-up is necessary, in addition to cessation of exposure. In children with lead levels that range from 15-19 µg/dL, there is a need for a complete workup. An evaluation of kidney, cardiovascular and neurologic function needs to be done when levels between 20-44 µg/dL of lead are established . At levels of > 45 µg/dL, chelation therapy is necessary. Succimer is the drug of choice in patients with moderately elevated lead levels (45-64 µg/dL), while EDTA is administered for very high levels ( > 70 µg/dL) .
The prognosis almost solely depends on the severity of poisoning, which is directly correlated with the amount of lead introduced into the body. Acute, significant lead poisoning may have a poor prognosis and is marked by a development of serious manifestations, such as seizures and coma. Chronic exposure, however, may lead to symptoms and signs that can become irreversible despite adequate treatment. Hence, the focus of lead poisoning in children is on prevention.
Lead is a naturally-occurring metal used in various branches of the industry and children are particularly sensitive to its toxic effects compared to adults . The principal source of exposure in children is either ingestion or inhalation of lead dust and particles in lead-based painted houses. Various other routes of exposure have been identified, including contact with fashion accessories, pellets, condiments, domestic items and folk remedies . Water consumption from lead pipes is also a frequent mode of poisoning. Additionally, lead can cross the placental barrier and cause fetal lead poisoning in women who have increased levels of lead in the circulation and bones.
During the second half of the 20th century, the removal of lead from gasoline and paint has dramatically reduced the number of children who suffer from lead poisoning. This environmental hazard, however, was still considered to be one of the most significant causes of toxicity among children in the US at the end of the millennium , with more than 25% of homes that have more than 1 children in the US having hazardous lead compounds . Today, this condition is still encountered despite various preventive strategies and estimates suggest that more than 300,000 children in the US live in conditions that contain increased lead levels . Children aged 1-5 years seem to be at the highest risk for lead poisoning, with an approximate prevalence of increased blood lead levels equal to 1.6% according to some studies . Several housing characteristics, such as the presence of lead-based paint, especially if there are chips or increased amount of dust, communities where old houses haven't been renovated and proximity to lead-consuming factories are shown to place children at risk. African-American children are shown to be at a substantially increased risk for lead poisoning compared to Caucasians and Hispanics . A refugee status has also shown to be a precipitating factor for lead poisoning . The presence of lead in maternal bone is also a significant factor, as this metal enter the blood and readily crosses the placenta .
Regardless of the mode of exposure, lead reaches the circulation and binds to RBCs, from where it is distributed to various organs and tissues. Firstly, lead is known to directly influence the process of heme synthesis by interfering with several enzymes. Inhibition of δ-aminolevulinic acid dehydratase (ALAD), aminolevulinic acid synthetase (ALAS) and ferrochelatase occurs. An additional consequence is marked reduction of RBC life span, eventually leading to anemia . The central nervous system, however, is the principal site of toxicity, but the exact mechanisms remain to be elucidated. Current studies suggest that lead inactivates various antioxidant enzymes, including glutathione peroxidase (GSH), thus creating favorable conditions for oxidative stress and cell death. Additionally, lead is shown to interfere with calcium ion channels. An impact of lead on protein kinase C disrupts signal transduction cascade . Sodium concentrations are also thought to be disturbed . This metal is able to reside in erythrocytes and some other types of cells for a relatively short period of time (approximately 30 days), but its half-life in the skeletal system is more than 20 years.
Lead poisoning in children has dramatically dropped since the introduction of various preventive strategies in the past 40 years, such as removal of lead from gasoline, but a more advanced form of prevention are needed to completely eradicate this condition. Parent education regarding the potential sources of lead in old housing communities and regular screening of children who are known to be at risk are surely beneficial in identifying this condition in its initial stages. If borderline levels are found (around 10 µg/dL), regular follow-up is necessary to prevent potential sequelae.
Despite various steps in reducing the burden of lead poisoning in both children and adults worldwide, this environmental hazards still cause significant toxicity and results in symptoms that may significantly impair the quality of life. Lead is a naturally-occurring metal that is used for various industrial purposes , but the most common route of exposure in children is ingestion of dust and chips from deteriorating lead paint that still persists in numerous homes , both in developed and developing countries. It is established that more than 300,000 children in the United States have elevated blood lead levels and studies have determined a higher rate of lead poisoning in African-Americans and Mexican-Americans . Additionally, poor housing condition and proximity to potential sources of lead such as smelters and factories are also shown to be predictive factors for identifying children who are at risk . Once lead is introduced into the human body, it binds to red blood cells, after which it can be distributed to various parts, including soft tissues and bones (where it deposit and has a half-life of more to 20 years) . The CNS, however, is the site of greatest toxicity. Presumably, lead interferes with various functions of the nervous system, including calcium-dependent signaling, oxidative phosphorylation, and inhibition of antioxidant enzymes, leading to induction of oxidative stress and apoptosis  . Additionally, lead directly inhibits the synthesis of heme. Toxic effects of lead could be achieved even when its concentration is very low, less than of 10 µg/dL , and different symptoms may appear depending on the severity of poisoning. In the setting of acute poisoning, where large concentrations of lead are seen in the circulation, encephalopathy, cerebral edema, vomiting, seizures and altered mental status that may progress to irreversible coma are observed . Chronic exposure, which is more common, is characterized by cognitive impairment and intellectual disability . Additional features may be reading disabilities, irritability, and tendency toward aggressive behavior and delinquency later in life . Other, non-specific symptoms, may include a headache, abdominal pain, and nausea. Making the diagnosis may not be easy and requires a high dose of clinical suspicion that may be created only by obtaining proper patient history with an emphasis on socioeconomic status, living conditions and potential exposure to various environmental hazards. Confirmation of lead poisoning may be obtained by measuring levels of lead in whole blood (as lead is sequestered in RBCs), while additional studies can support the diagnosis, including complete blood count (CBC) that reveals anemia and X-rays of the abdomen and long bones that may reveal radiopaque lead particles and increased calcification, respectively . Treatment principles somewhat vary depending on the severity of poisoning, but invariably comprises cessation of exposure and chelation therapy. The threshold for chelation therapy is lead levels over 45 µg/dL, in which case succimer is considered a first-line therapy. In more severe cases (> 70 µg/dL), ethylenediaminetetraacetic acid (EDTA) is considered to be superior to succimer . Despite adequate treatment, symptoms and signs of lead poisoning are often irreversible, making prevention one of the key steps in reducing the burden of this condition. Removal of lead from gasoline has led to significant reductions in the number of cases, but screening of children who are considered to be at risk, replacement of lead-based compounds in housing and several other measures are shown to be valuable in further diminishing this condition in children, but in adults as well.
Lead is a naturally occurring metal that is readily used in numerous industries in the world. Lead poisoning in children, but in adults as well, is a condition characterized by a development of symptoms as a result of toxic effects of lead in the human body. In most cases, children are poisoned through unaware exposure to lead-based paint and dust particles which are either inhaled or ingested. Various other modes of intoxication have been described, including breastfeeding in mothers with high blood lead concentrations, since lead readily crosses the placenta. Even though marked reductions of lead intoxication have been observed in the past few decades, primarily through removal of lead from gasoline, more than 300,000 children are shown to be at risk of lead poisoning in the United States. Risk factors include living in old housing communities that have lead-based painted walls and close proximity to factories using lead. African-Americans are shown to be at a much higher risk for lead poisoning than Caucasians and Hispanics. Lead is able to cause toxic effects by initial lodging inside red blood cells and causing marked disruption of hemoglobin synthesis. More importantly, however, it causes deleterious effects in the central nervous system, presumably due to its ability to inhibit enzymes that battle free radicals and interfere with various ions, such as calcium and sodium. As a result, symptoms related to the central nervous system appear, although they depend on the severity of intoxication. In the setting of acute poisoning, loss of consciousness, seizures, and coma are main findings. Chronic poisoning, on the other hand, is distinguished by a slowly progressive decline in various cognitive functions, including learning and reading difficulties, irritability, attention deficits, whereas a tendency toward aggressive behavior in later life has also been documented. To make the diagnosis of lead poisoning in children, a detailed patient history may reveal the potential source of lead, while additional studies are needed to confirm the diagnosis. A complete blood count, kidney function tests and whole-blood levels of lead should be evaluated. Additionally, imaging studies such as X-ray of the abdomen may reveal lead particles in the stomach that are the source of acute poisoning. X-ray of the bones may reveal distinct pathological changes that can support the diagnosis. Usually, lead levels of > 10 µg/dL are a definite diagnosis, after which appropriate treatment may be started. In children with mildly elevated lead levels, cessation of exposure and parent education are sufficient, but those that have very high lead levels ( > 45 µg/dL), the use of "chelation" therapy is necessary. Chelation drugs bind to various metals and excrete them in urine and in the case of lead, succimer and EDTA are two most commonly used. Despite adequate treatment, neurological symptoms in children are often irreversible, which is why prevention is imperative in reducing the number of children affected by this condition. Screening of children who are shown to be at risk, removal of lead-based products from homes and regular follow-ups of children who have been exposed to lead are some of the most important strategies.