Effect of Minerals and Food on Uptake of Lead from the Gastrointestinal Tract in Humans

Abstract

<jats:p> 1 Eight adult male volunteers ingested <jats:sup>203</jats:sup>Pb as chloride with varying amounts of CaCO<jats:sub>3</jats:sub> and NaH<jats:sub>2</jats:sub>PO<jats:sub>4</jats:sub>. The uptake from the gastrointestinal tract declined progressively as the amount of minerals taken simultaneously was increased, in agreement with the findings of Blake (1980). </jats:p><jats:p> 2 With four of the volunteers, further tests were done to compare the effect of the two minerals together and separately. With no minerals, uptake averaged 63.3% (range 58.6-66.7%). The two together (200 mg Ca and 140 mg P) reduced it to 10.6% (range 8.6-12.8%), but neither mineral by itself was nearly so effective as the two together. </jats:p><jats:p> 3 A lamb was injected with <jats:sup> 203</jats:sup>Pb and butchered after 6 days. Six volunteers ate the liver or kidneys as part of a meal. Uptake of <jats:sup>203</jats:sup>Pb incorporated in the offal averaged 2.8% (range 1.6-4.7%). When <jats:sup>203</jats:sup>Pb in solution was taken with inactive offal in a similar meal, uptake averaged 3.0% (range 1.7-3.6%). Thus incorporation of <jats:sup>203</jats:sup>Pb in liver or kidney did not affect the uptake. </jats:p>

Dietary lead intakes for mother/child pairs and relevance to pharmacokinetic models.

“…In the EPA Integrated Exposure Uptake Biokinetic (IEUBK) model (9), the higher absorption values among adult males are applied to children up to 7 years old. The adult values for gastrointestinal lead uptake are fairly well validated using long-term mass balance studies (12,13), radioactive tracers (14)(15)(16)(17)(18)(19), and stable isotope tracers (20,21). Most adult subjects were males.…”

“…Metabolic studies among adults show that when lead is ingested during fasting the fractional absorption increases from the range of 5-20% to approximately 60-80% (16,18,19,21). Consequently, national data from the United States that indicate occurrence of food insufficiency among lowincome families raise profound concerns for many reasons, including increased susceptibility to lead toxicity.…”

Contribution of Lead from Calcium Supplements to Blood Lead

“…Tracer studies have demonstrated that in the absence of additional calcium, gastrointestinal absorption of lead was greater when lead was ingested by fasting subjects given soluble lead compounds in distilled water than when lead was ingested in the presence of food. Lead absorption in nonfasted subjects on either a normal diet or a controlled diet, in which nutritional content was known, ranged from approximately 3% to 10%, whereas lead absorption in fasted subjects who received soluble lead in distilled water (with no additional calcium) ranged from approximately 30% to 76% (20)(21)(22)(23)(24)33,34). The absence of calcium and other minerals in the gastrointestinal tract at the time of lead ingestion is a major reason for increased lead absorption in fasting subjects compared with nonfasting subjects (20)(21)(22)(23)(24)33,34), although when calcium and other minerals are present, differences seen between fasting and nonfasting subjects essentially disappear (22,23,32).…”

“…We were concerned about the scientific validity of the California judgment in light of earlier investigations from tracer studies in both animals and humans demonstrating limited uptake of lead from the gastrointestinal tract in the presence of calcium (± phosphorus; Figure 1) (20)(21)(22)(23)(24). These experiments, however, were undertaken at times of considerably higher intakes of lead with small numbers of subjects and mostly over limited time periods.…”

A Review of the Potential Issues of Pollution Caused by the Mineral Elements, Mercury, Lead and Arsenic, Its Possible Impacts on the Human Beings and the Suggested Solutions

“…Calcium deficiency increases lead absorption and lead retention, and is a risk factor for increased maternal lead transfer. In which, Methyl mercury crosses the placenta and reaches the fetus, and is concentrated in the fetal brain at least 5 to 7 times that of maternal blood [82][83][84][85][86]. Prenatal methyl mercury exposure at high levels can induce widespread damage to the fetal brain.…”