Factors affecting blood lead concentrations in three groups of children of different ethnic origin have been investigated. Dietary lead intakes were similar for the three groups, the average lead intakes lay in the range 110-150 micrograms/week. Blood lead concentrations were not related to ethnic origin when the effect of other factors was allowed for. Children who washed their hands before eating had significantly lower blood lead concentrations than those who did not.

Calcifediol↗

PubMed1979

Geochemical and man-made sources of lead and human health.

Multiple sources of Pb have been identified for human populations, but there is little agreement as to their relative significance. Marked regional geochemical anomalies in the distribution of Pb have been identified and, in one district, their impact on rural communities has been determined. The absorption of ingested Pb is modified by its chemical and physical form, by interaction with dietary minerals and lipids and by the nutritional status of the individual. Studies on children of various ethnic groups have demonstrated differences in soft tissue Pb burdens which may in part have a nutritional basis. Erythrocyte protoporphyrin determinations suggest that metabolic disturbances attributable to Pb may occur at soft tissue burdens previously regarded as acceptable. The problem of defining an adverse health effect in relation to environmental sources of Pb is discussed.

Aerosols↗

PubMed1979

Recognition and management of children with increased lead absorption.

Explore the source record for details and available documents.

Absorption↗

PubMed1977

Absorption and endogenous faecal excretion of calcium by low birthweight infants on feeds with varying contents of calcium and phosphate.

Low birthweight infants aged 4-41 days were given from birth one of three experimental milk formulae varying widely in content of calcium and phosphate. Ca and P in feed, urine, and faeces were measured between carmine markers corresponding to a metabolic period of 48 hours. Calcium enriched in 46Ca to provide a marker for the dietary Ca was added to one feed and 46Ca measured in urine and faeces. True absorption of Ca and endogenous excretion into the bowel could then be inferred. True absorption of Ca was proportional to Ca intake and independent of P intake. Endogenous faecal excretion seemed to be independent of both Ca P intakes, and varied widely between different infants in the range 4-150 mg/day. Urine Ca was low and retention was essentially the difference between true absorption and endogenous faecal excretion. Retention of Ca tended to be much greater on a high Ca intake, but the variability in retention between infants on a given intake was large, paralleling the variability in endogenous faecal excretion. The variability in plasma Ca concentrations in newborn infants may in part be a consequence of wide individual variability in endogenous faecal excretion. The 46Ca marker technique provides a means of investigating the factors determining this variability.

Calcium↗

PubMed1977

Urinary and faecal excretion of marker calcium (46Ca) by low birthweight infants.

Low birthweight infants were given calcium enriched in 46Ca in a single feed. The specific activity of successive urine samples showed that the absorption of the marker was largely complete in about 4 hours. The rate of decrease of urinary specific activity after 3 1/2 hours was exponential and very similar in 8 sets of observations in 6 infants. Its extrapolation backwards to 1 hour may indicate the size of the exchangeable calcium pool, usually about 200 mg/kg body weight. Completeness of faecal collection for estimation of 46Ca is essential for accurate determination of true absorption and endogenous faecal excretion of natural Ca. In 5 infants examined, nor marker was detectable in faeces excreted later than 48 hours after the first stool containing marker. Nevertheless, reasons are given why a collection period limited to 48 hours may sometimes involve error.

Calcium↗

PubMed1977

Significance of Ca-soap formation for calcium absorption in the rat.

The significance of calcium soap formation in the inhibition of calcium absorption has been studied in rats. 47Ca labelled soaps of fatty acids were introduced into the duodenum and the absorption of calcium measured after four hours in a whole body counter. The absorption of calcium was inversely correlated with the chain length of the fatty acid varying from 1% for Ca-stearate to 60% for Ca-hexanoate. Increasing the degree of unsaturation of the fatty acid was accompanied by increased calcium absorption. The availability of calcium for absorption from the soaps was correlated with their solubility in 1% aqueous Na-tauroglycocholate. The percentages of calcium as soap in the small intestine and the faeces after intragastric administration of calcium and fats were similar, which suggests that the faecal content of calcium soaps is an index of intestinal soap formation. Soap formation was negligible when CaCl2 was given with tristearate, triolaeate, or tridecanoate and no depression of calcium absorption was observed. Calcium absorption was markedly impaired by the addition of phosphates at a Ca/P ratio of 1:1 irrespective of the presence of neutral fats. Stearic acid resulted in significant soap formation and reduced calcium absorption. The degree of Ca-soap formation and the inhibition of calcium absorption were well correlated. The results suggest that, although calcium soap formation may markedly depress calcium absorption in the rat, no significant soap formation takes place when fats are given in the form of triglycerides.

Animals↗

PubMed1976

The influence of dietary minerals and fat on the absorption of lead.

The nutritional factors influencing the absorption of lead from the gut have been studied using both intact animals and ligated gut loop preparation. Short-term feeding studies have been made in groups of six animals using diets of constant lead content (0.075%) but in which the nutritional components were varied sequentially. Dietary lead was labelled with 203Pb. Absorption was determined in the carcass and individual organs by means of a small-animal wholebody counter. The results showed that absorption was enhanced to twenty-times control value by diets deficient in minerals and seven-fold by diets of high fat content. Conversely, high mineral diets have been shown to result in a two-fold reduction in lead absorption. The interaction of lead with individual dietary components has been further studied under controlled conditions using ligated gut loop preparations. Using this technique the relative roles of luminal interaction and tissue response for lead absorption have been explored and the kinetics of lead absorption determined.

Animals↗

PubMed1976