Scientific Papers

Hematological Effects

Does Lead Cause Blood Disease?
There are hematological effects caused by lead poisoning. The earliest known manifestations of lead toxicity include a localized paralysis of extensor muscles in the forearm (i.e., wrist-drop),1 encephalopathy (brain disease)1 and in rarer cases anemia (too few red blood cells).2

What is the Connection Between Lead and Anemia?
Lead poisoning in children rarely results in anemia. Although lead toxicity and iron deficiency have similar risk factors, children with elevated blood-lead-levels have anemia that is most likely caused by iron deficiency.2

When anemia is secondary to lead toxicity it is usually mild, hemolytic (breaking down red blood cells) and normocytic (lowering the volume of hemoglobin). Hemoglobin is the iron-containing protein found in red blood cells that transport oxygen throughout the body. Lead also inhibits the body’s ability to create hemoglobin which lessens the oxygen capacity of the blood.3

The EPA estimates the threshold of blood-lead-level (BLL) for a decrease in hemoglobin to be 50 µg/dL for occupationally exposed adults and approximately 40 µg/dL for children. Other studies have indicated a lower threshold of 25 µg/dL for children might be more appropriate.2

High-level lead exposure can also result in hemolytic anemia defined as a breakdown of the red blood cells. This profound form of anemia is only evident when the BLL is significantly elevated for prolonged periods.

Can Lead Cause Other Blood Related Issues?
Many bodily processes including neural, renal and endocrine can be upset when lead interferes with the process that make red blood cells. Elevations in blood pressure is also associated with lead exposure.4 On a population basis, it is estimated that lead exposure can account for a 1% to 2% variance in blood pressure.1

References
  1. Lead Poisoning in a Historical Perspective. Sven Hernberg, American Journal of Industrial Medicine, 38:244±254, 2000, p. 245
  2. Erythrocyte Delta-Aminolaevulinic Acid Dehydratase Activity and Blood Protoporphyrin Concentrations as Indices of Lead Exposure and Altered Haem Biosynthesis. Meredith, Moore & Goldberg, Clinical Science, ;56(1):61, 1979
  3. Lead Toxicity: What Are the Physiologic Effects of Lead Exposure? Agency for Toxic Substances and Disease Registry, August 20, 2007
  4. Erythrocyte Delta-Aminolaevulinic Acid Dehydratase Activity and Blood Protoporphyrin Concentrations as Indices of Lead Exposure and Altered Haem Biosynthesis. Meredith, Moore & Goldberg, Clinical Science, ;56(1):61, 1979
  5. Lead Exposure and Cardiovascular Disease—A Systematic Review, Navas-Acien, Guallar,Silbergeld & Rothenberg, Environmental health perspectives 115 (3): 472–82, 2007