Diets, lead concentrations

Given drinking water with 10 mg Pb/L for 51 days diets were either low in calcium (0.3% Ca) or adequate in calcium (3% Ca) Birds given low calcium diets accumulated up to 4 times more lead in tissues than finches on high calcium diets. Lead concentrations in mg/kg DW for low Ca vs. high Ca diets were 2.4 vs. 0.6 in liver, 4.9 vs. 1.5 in kidney, and 48 vs. 8 in bone 52... 

Gulson et al. (1998) used measured lead isotope ratios (207Pb/206Pb and 206Pb/204Pb) in mothers breast milk and in infants blood to establish that, for the first 60-90 days postpartum, the contribution from breast milk to blood lead in the infants varied from 36% to 80%. Maternal bone and diet appear to be the major sources of lead in breast milk. Mean lead concentration ( standard deviation) in breast milk for participants in the study was 0.73 0.70 pg/kg. 

Sherlock JC, Quinn MJ. 1986. Relationship between blood and lead concentrations and dietary lead intake in infants The Glasgow Duplicate Diet Study 1979-1980. Food Addit Contam 3 167-176. 

The serum concentration of calcitriol varies inversely with phosphate throughout the day. Feeding subjects on low phosphate diets leads to a fall in serum phosphate and an increase in circulating calcitriol. It is not clear whether or not this is a direct effect of phosphate on the kidney hydroxylases. 

Free sulfate occurs in the plasma at concentrations of 1 to 2 mAf, The sulfate in the plasma and glomerular filtrate has been a concern for those interested in calcium status. Consumption of high-protein diets leads to increases in urinary calcium levels. This effect has been attributed, in part, to the catabolism of sulfur amino adds to yield free sulfate. The sulfate forms a complex with the calcium in... 

Lead concentrations in different plants in Poland were up to 0.3 mg/kg fresh matter in vegetables (90% of samples), <0.1 mg/kg fresh matter in fruits (90% of samples), and >0.3 mg/kg fresh matter in cereals (25% of samples). In the Katowice Province, lead contents in vegetables (carrot, red beet, parsley, celery) varied between 0.50-280 mg/kg dry matter. Exposure to lead from vegetables was 1.5 mg/week per person. The results ranged between 4.8 4.0% of PTWI, whereas in the reference area these values amounted to 6.0% of PTWI for lead. The elimination of vegetables with high contents of lead in diet may reduce the dietary intake to 2.0-18.4% of PTWI (Gzyl, 1997). 

A high-protein diet leads to increased production of urea. Drinking more water increases the volume of urine, ensuring elimination of the urea from the body with less strain on the kidneys than if urea were at a higher concentration. 

In oysters, for example, BCF values varied from 3450 to 6600 after exposure to solutions containing 1.0-3.3 p,g Pb +/L for 140 days, but oysters and their progeny were apparently unaffected at whole body burdens (less sheU) up to 11.4 mg Pb/kg DW. Many species of aquatic biota contain lead in amounts >1000.0 mg/kg FW (>10,000.0 mg/kg DW) including some marine seaweeds, freshwater macroph5 s and algae, annehds, crastaceans, echinoderms, mollusks, and teleosts presumably, the lead was sorbed passively and little, if any, was incorporated biologically. Variations in lead concentrations in aquatic biota probably reflect the ability of individual species to adsorb waterborne lead, and may be a direct function of the ratio of surface to body weight. The residence time of lead in aquatic biota seems to be related to the route of administration Tbl/2 values were 9 days by waterborne routes and 40 days by diet. 

Sodium deficiency in animals occurs in many parts of the world, but especially in the tropical areas of Africa and the arid inland areas of Australia, where pastures contain very low concentrations of the element. A deficiency of sodium in the diet leads to a lowering of the osmotic pressure, which results in dehydration of the body. Symptoms of sodium deficiency include poor growth and reduced utilisation of digested proteins and energy. In hens, egg production and growth are adversely affected. Rats given experimental diets low in sodium had eye lesions and reproductive disturbances, and eventually died. 

The dietary intake of lead has been estimated by a number of methods, the principal ones being firstly the analysis of duplicate portions of meals for total lead and secondly a composite method, whereby typical lead concentrations in the various components of a diet are separately defined and the total lead intake becomes the sum of the lead intakes from the various components, as in Table 7.4. Some of the more recent data, reported since 1970, are summarized in Table 7.5. Clearly there is a high degree of variability in dietary lead intake from individual to individual, as well as from country to country. Typical intakes probably lie in the range 100-200 Mg day for adults and somewhat lower but not proportionately so, for children at 50-150 Mg day -... 

The lead concentration of the purified diets used varied between 18 and 45 ng/g. The addition of 1 ug/g of lead as the acetate completely prevented and, in the case of crossover experiments in newborn rats reversed the signs of deficiency. Results of experiments with intermediate levels of lead supplementation have not yet been reported. New-... 

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