Heavy metals are naturally occurring, high-density elements such as arsenic, cadmium, chromium, lead, and mercury. These five metals are the most common causes of heavy metal poisonings. Zinc is also of concern. Heavy metals are widely distributed in the environment and can be toxic even at low concentrations. Exposure commonly occurs via ingestion, inhalation, or skin absorption. Occupational exposures are common and can occur in mining, refining, and smelting operations. Lead exposure disproportionately affects lower-income, inner-city communities due to older housing stock and historical industrial contamination. Adverse health effects of exposure to heavy metals vary by type and form of metal, exposure factors (eg, route, dose, duration), and individual patient characteristics (eg, age, sex). Toxicity management includes supportive treatments, decontamination, chelation, and/or surgery depending on the clinical situation and metal involved. For some types of heavy metal toxicity, there are no definitive treatments. Acute poisoning with arsenic and chromium can be fatal. Pregnant and breastfeeding patients and young children are particularly vulnerable to heavy metal exposure due to its effects on fetal and child development. In cases of suspected exposure, patients should be evaluated with a thorough history, including detailed occupational and social histories, and a physical examination, with laboratory tests and imaging as needed.
Case 2. SB is a 6-year-old patient who presents with his parents for a well-child assessment as part of requirements for resettlement through the US Refugee Admissions Program. SB recently immigrated to the United States with his family due to ongoing conflict in their home country. They live in a duplex apartment. SB’s parents note that he enjoys a variety of foods, although they do not eat much meat. He is meeting developmental milestones, but they note that he is quiet compared with his older siblings.
SB is at the 7th percentile for height and 10th percentile for weight. The required screening laboratory tests for his immigration physical included a complete blood cell count and venous blood test for lead. You note a hemoglobin level of 10.2 g/dL and blood lead level of 25 mcg/dL.
Heavy metals are naturally occurring, high-density elements such as arsenic, cadmium, chromium, lead, and mercury. These five metals are the most common causes of heavy metal poisonings.25 Zinc is also a metal of concern. Heavy metals are widely distributed in the environment as a result of their use in various industries.
These metals can be toxic even at low concentrations. They can bioaccumulate in plants and animals in the environment. The degree of toxicity in humans depends on several factors, including dose and route of exposure. Age, sex, genetics, and health status also influence the effects on individuals who are exposed.
Arsenic
Elemental arsenic is a steel- or silver-gray brittle solid. It is also a well-known poison. Arsenic is used in a variety of industries, including agriculture (pesticides) and lumber (treated wood). It was used historically for treatment of syphilis, yaws, amoebic dysentery, and trypanosomiasis.26
Exposure typically occurs via ingestion, inhalation, or skin contact with food, air, water, or soil. Arsenic can bioaccumulate in plant crops and is of particular concern in grains (eg, rice) and root vegetables. It also can be found in some juices. Arsenic pollution can occur through volcanic eruptions, soil erosion, and anthropogenic activities.26
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