Lead toxicity affects several organ systems including the nervous, hematopoietic, renal, endocrine, and skeletal systems depending on the age of the subject and the lead dose, but the effects of major concern today is the impairment of cognitive and behavioral development in infants and young children. Effects occur from low-level exposures from various environmental sources including lead- based paint and household dust in homes containing surfaces covered with lead-based paint. Lead in air, food, and water are also of concern but hazards from these sources as well as lead in dust have been greatly reduced by the removal of lead from gasoline. The elimination of lead solder from cans has reduced the hazard of exposure to lead from canned food; in particular canned milk for infant formula. There is increasing awareness of the hazard from lead in tap water contaminated from solder and lead- containing fittings in residential plumbing. Lead in water is more efficiently absorbed than is lead in food; lead in water used for infant formula is an additional hazard. Measurable effects occur with blood lead concentration in the 0.48.72 mu mol/L (1-15 mu g/dL) range and more than one million children in the United States have blood concentrations in this range or higher. Nutritional deficiencies of essential metals can increase the hazard from lead exposure by enhancing absorption and toxicity of dietary lead.
Lead-Calcium Interactions.
Lead-calcium interactions are probably the most studied nutritional factors affecting lead toxicity, both clinically and experimentally. There are several suggestions in the lead toxicity literature that the two metals are metabolically related. In 1926 Aub et al (4), pointed out that physiologically, the "Pb stream"" follows the "calcium stream." ".
Some 25 years ago Six and Groyer (5) showed that a low-calcium diet containing varying amounts of lead fed to rats resulted in considerably higher blood and tissue concentrations of lead than occurred in rats fed a normal-calcium diet of 0.