Childhood Lead Poisoning: Sources, Outcomes, Treatments

Childhood Lead Poisoning: Sources, Outcome, Treatment and Global Dimensions

 

John Rosen, Professor of Pediatrics, Head, Division of Environmental Sciences, The Children's Hospital at Montefiore, Albert Einstein College of Medicine, New York City, U.S.A. (Jrosen5@ix.netcom.com) spoke on the sources, treatment, outcome and global dimensions of childhood lead poisoning.

Dr. Rosen pointed out that both the Centers for Disease Control (CDC) and the Environmental Protection Agency (EPA) have concluded from detailed studies that there is no safe level of lead in the blood of young children (Figure 6.1).; however exposure to environmental lead remains a major  global problem (Figure 6.2).

 

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Currently, in the U.S., the major source of lead is lead-based paint still present in 25 million homes. In many developing countries there is additional exposure to leaded gasoline and to industrial emissions (“point sources”) (Figure 6.3).

 

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Dr. Rosen explained that in the U.S. there are still many cases of lead poisoning and he cited examples of these cases.

Dr. Rosen also presented data on the lead concentrations of new household paints in various countries (Figure 6.4). Clearly the problem of lead in household paint exists in many countries and efforts should be made to remove lead from all paints. Although lead is no longer in paints in the U.S. children there can be exposed to leaded paints through contact with imported toys (Figure 6.5). Such toys have been recalled and the principle now should be appreciated: no toys should be painted with paint containing lead.

 

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Dr. Rosen described an outbreak of lead poisoning in the U.S. (Figure 6.6) which was traced to imported, lead-contaminated food. He went on to describe toxic treats or toxic candies (Figure 6.7) made in Mexico and imported into the U.S. These items are contaminated with lead and, although initially recalled, they are still available in the U.S.

 

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The U.S. Consumer Product Safety Commission is charged with the responsibility of controlling products and ensuring that they are free of lead. However it is difficult for the Commission to quickly detect a contaminated product because of regulations which demand definitive evidence of toxicity (Figure 6.8). It is difficult to recognize problems early and institute preventative measures.

 

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Dr. Rosen feels The European Union (EU) has become the “moral and regulatory leader” in environmental health (Figure 6.9). The EU's “REACH” regulation (Figures 6.10 and 6.11) has established a system for aggressively evaluating all chemicals to which the population is exposed. This precautionary approach permits early action, before there is evidence of harm.

 

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In the U.S. a level of 10ug/dl blood lead is thought to be indicative of lead poisoning (Figure 6.12) There are at least 350,000 children in the U.S. with blood lead levels greater than 10ug/dl (Figure 6.13). Dr. Rosen emphasized that the level of 10ug/dl is too high and the safe level should be set at 5ug/dl or less.

 

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The fall in blood lead levels in the U.S. (Figure 6.14) (from 12.8 ug/dl in 1976 to current levels of less than 2ug/dl) is due to the removal of lead from gasoline, then paint and then solder.

 

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The effect of lead exposure on intellectual development has been well studied. Figure 6.15 shows the effect of increased blood lead levels on IQ. Dr. Rosen cited published studies which have specifically addressed blood lead levels less than 10ug/dl (Figure 6.16). These studies revealed effects of even these low levels on intellect. One study by Tellez-Rojo et al showed effect at levels less than 7.5ug/dl. The publication by Miranda et al showed an effect on academic performance at levels below 2 ug/dl. The various neuropsychologic manifestations of chronic lead poisoning are shown in Figure 6.17.

 

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The economic impact of lead pollution is significant (Figure 6.18).

 

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The approach to screening children for lead poisoning and the role of the pediatric health care provider are summarized in Figures 6.19, 6.20, 6.21, 6.22, 6.23. Dr. Rosen provided a guide to action to be taken based on screening blood lead levels (Figure 6.24). However, he made the point that “By the time children are diagnosed with blood levels 20-44 ug/dl, there is irreversible neurobehavioral-cognitive damage”. The approach to the problem of lead pollution is prevention Figure 6.25.

 

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