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  • Updated 05.20.2024
  • Released 01.06.1995
  • Expires For CME 05.20.2027

Lead poisoning in childhood

Introduction

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 a lead level of 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 author discusses lead as an environmental risk factor, its effects on health, and its management. He also discusses 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 aged 1 to 5 years 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 disease susceptibility.

• 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 Australian pediatrician Alfred Jefferis Turner (1861-1947) in 1892.

Australian pediatrician Alfred Jefferis Turner (1861-1947)

Turner provided the first clinical description of childhood lead poisoning in 1892. (Source: Wikimedia Commons. Public domain. Photograph restored by Dr. Douglas J Lanska.)

While a resident at the Children's Hospital in Brisbane, Australia, Turner described four children with ocular neuritis, recurrent emesis, and headache (168). Subsequent patients were also noted to have muscle-wasting, wrist-drop, and footdrop. Although the symptoms were initially attributed to a localized basal meningitis, Turner and his chief, Australian ophthalmologist John Lockhart Gibson (1860-1944), subsequently deduced that these children were suffering from lead poisoning (61; 63; 169; 138), which was found to originate from the powdered residue of deteriorating paint in the children's homes (62). 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" or Burton lines, on his gum margins (164).

Australian ophthalmologist John Lockhart Gibson (1860–1944)

Gibson was instrumental in recognizing the importance of lead-based paint in the development of childhood lead poisoning from 1897 to 1904. (Source: Gibson JL. A plea for painted railings and painted walls of rooms as the sourc...

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, pediatrician Randolph Kunhart Byers (1896-1988) and child psychologist Elizabeth Evans Lord (1890-1943) at Boston Children's Hospital presented a detailed description of 20 school-aged children who were diagnosed with symptomatic lead poisoning during their early years (24). 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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