Childhood lead poisoning

Jose Porras BS (Mr. Porras of Dartmouth-Hitchcock Medical Center/Geisel School of Medicine at Dartmouth has no relevant financial relationships to disclose.)
Brandon Root MD (Dr. Root of Dartmouth-Hitchcock Medical Center/Geisel School of Medicine at Dartmouth has no relevant financial relationships to disclose.)
Robert J Singer MD (Dr. Singer of Dartmouth-Hitchcock Medical Center/Geisel School of Medicine at Dartmouth has no relevant financial relationships to disclose.)
Bernard Maria MD, editor. (Dr. Maria of Icahn School of Medicine at Mount Sinai and Director of Pediatric Neurology and Developmental Medicine at Goryeb Children)
Originally released January 6, 1995; last updated November 21, 2016; expires November 21, 2019

This article includes discussion of childhood lead poisoning, lead encephalopathy, lead intoxication, and plumbism. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Childhood lead poisoning is a growing concern, particularly because new findings have shown that low-level, typical-population lead exposures are associated with the development of cognitive and behavioral deficits. In response to these findings, the United States Centers for Disease Control and Prevention has set the lead level greater than 5 µg/dl as the minimum value for intervention. The mechanisms of action of lead depend on the time of exposure and the degree of CNS maturation. Early-life lead exposure may lead to disease susceptibility throughout the life course. In this article, the authors discuss lead as an environmental risk factor, its effects on health, and its management. They also discuss new trends in research describing how lead leads to epigenetic alterations that may underlie many of the behavioral phenotypes observed in patients exposed to even minimal amounts of lead.

Key points

 

• The toxic lead reference level is currently 5 µg/dL as determined by the Centers for Disease Control and Prevention (CDC), which reflects the lead blood levels of children age 1 to 5 in the United States who are in the highest 2.5%.

 

• Cognitive and behavioral deficits have been linked with population-typical lead exposures.

 

• Management is generally aimed at preventing further exposure. Chelation therapy is only indicated for very high levels (> 45 µg/dL).

 

• Lead influences fetal epigenetic programming that may alter phenotype and consequential disease susceptibility, and maternal bone lead is a marker for adverse fetal outcome.

 

• Calcium supplementation during pregnancy and lactation is associated with reduced lead levels.

Historical note and terminology

Widespread commercial use of lead has resulted in the dissemination of the metal in the environment. Recognized since antiquity, the first clinical description of childhood lead poisoning was provided by A Jefferis Turner in 1892. While a resident at the Children's Hospital in Brisbane, Australia, he described 4 children with ocular neuritis, recurrent emesis, and headache (Turner 1892). Subsequent patients were also noted to have muscle-wasting, wrist-drop, and foot-drop. Although the symptoms were initially attributed to a localized basal meningitis, Turner and his chief J Lockhart Gibson subsequently deduced that these children were suffering from lead poisoning (Gibson 1897; Turner 1897), which was found to originate from the powdered residue of deteriorating paint in the children's homes (Gibson 1904). The first account of childhood lead poisoning from paint in the United States followed shortly thereafter, in a child with seizures and coma who had dark blue "lead lines" on his gum margins (Thomas and Blackfan 1914).

Long-term brain dysfunction is often seen in children who survive lead poisoning, and it was first described in relation to lead poisoning in 1943. Refuting conventional wisdom that the symptoms and effects of childhood lead poisoning could be reversed, Byers and Lord presented a detailed description of 20 school-aged children who were diagnosed with symptomatic lead poisoning during their early years (Byers and Lord 1943). These children underwent serial psychometric assessment and were found to have deficits in language skills, visual-motor skills, and modulation of behavior.

Lead exposure in children is believed to have reached its height in the late half of the twentieth century. Bans on lead-based paint and the phasing out of leaded gasoline in the 1970s and 1980s have contributed to a steady decline in environmental exposure.

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