Effects and Toxicity to Man

In a seven year study of school aged children in the United States, Angle and Mclntire [2] concluded that dust and soil fallout of airborne lead as well as dietary and unusual sources are all important in determining body burden. Intestinal absorption of lead was found to be as high as 42%, and in the absence of unusual 

In a study of 62 workers in a battery factory, Richter et al. [57] found that blood lead levels of 550-650 pg/1 caused medical and subclinical problems, with biochemical and insidious neuro-physiologic changes occurring at lower blood lead levels. They recommended that occupational 8-h exposures be lowered to 50 pg/m to keep blood lead levels in safe ranges. 

Haemopoietic System, Lead poisoning causes anemia by impairment of heme synthesis and by an increased destruction rate of redblood cells. Some of the steps in heme syntheses occur in the mitochondria, a site of lead accumulation. It is in the mitochondria that lead impairs the incorporation of iron molecules into the heme. Lead also decreases the life span of red blood cells but the mechanism responsible for this effect is not well understood [25]. 

Nervous System. Structural and functional nervous system effects of lead are apparent. These effects involve the brain, cerebellum, spinal cord, and motor and sensory nerves leading to specific areas of the body. Neural tissue is very sensitive to the toxic effects of lead with cases of brain swelling reported at even low lead concentrations. Severe subcellular damage is usually noted in the cerebellar cortex and cerebral cortex, and sometimes in the basal ganglia. This damage also impairs the flow of blood in the brain [25]. 

Renal System and Gastrointestinal Tract. The kidney is an excretory organ and therefore has a prominant role in lead metabolism. Lead has been found to cause a reduction in kidney transport of amino acids, glucose, uric acid, citric acid, and phosphate probably because of a decrease in energy production. This decrease in energy production is caused by a direct effect of lead on renal mitochondria, and enzymes responsible for energy production [25]. 

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