Reduction of lead absorption from the intestine in newborn rats

The metabolism and toxicity of lead, cadmium, mercury, and manganese in the postnatal period was studied in rats. Absorption, whole body retention, and organ distribution of 203Pb, "1115Cd, 203Hg, and 54Mn were determined after oral and parenteral administration of these radioisotopes. The acute oral toxicity (LD50) was determined after a single application of metal chlorides. The results obtained in sucklings show a very high intestinal absorption of all metals which is partly attributed to milk diet; a higher whole body retention, higher blood levels and a much higher accumulation in the brain; and a higher oral toxicity.These results indicate age specific differences in the pharmacokinetics of metals in sucklings. It seems reasonable to consider the early neonatal age as a critical period for metal accumulation and therefore for metal toxicity.The results are interpreted on the basis of current concepts of developmental physiology and pharmacology and suggestions for future research trends are made.All environmental chemicals which enter into the biological cycle have the potential of entering into the human body at all stages of its development. Metals represent a group of special concern, since the concentration of some toxic metals in the environment has already reached levels which might be harmful especially if combined with other factors which increase the metals' absorption, retention and toxicity. The question is raised whether the young, from birth and onward, might be more sensitive to toxic metals in the environment than are adults. A conclusive answer is difficult to give since for ethical reasons most of the data available at present have been obtained on animals. Moreover, many stages in the mammalian development cycle can be considered as "critical" in themselves, so that to assess the possible effects of an exposure in terms of the chemical form, dose, or route of administration of a metal is extremely difficult. A new field of developmental toxicology will have to be established in order to elucidate critical biochemical processes in the immature organism that might be responsible for differences in the metabolism and August 1978 toxicity of metals in these members of the population as compared to adults.The transfer of metals from mother to embryo and fetus and the gametotoxic, embryotoxic and fetotoxic properties of lead, cadmium, and mercury have been adequately reviewed in publications from earlier meetings of the Scientific Committee on the Toxicology of Metals (1-3). It is, however, astonishing how little information is available on the pharmacokinetics and effects of metals during the immediate postnatal period. This period, in which rapid changes in organ function and development occur and in which milk is the only nutritional source, has been neglected from the standpoints of both pharmacology (4) and environmental toxicology. The realization that exposure to toxic metals during the early neonatal period might cause irreversible behavioral (5, 6) and other changes seems at least to b...

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“…These results are in agreement with our previously published data on lead absorption in suckling rats (12,15).…”

Section: Gastrointestinal Absorptionsupporting

confidence: 83%

Influence of age on metal metabolism and toxicity.

Kostial¹,

Kello²,

Jugo³

et al. 1978

Environ Health Perspect

189

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“…Recently this has been confirmed in our laboratory (Barltrop and Meek, 1975). Carrierfree isotopes of lead have been used in some studies (Milev et al, 1970;Kello and Kostial, 1973;Kostial et al, 1971aKostial et al, , 1971b (Barltrop and Meek, 1975 The values for lead retention by animals fed on the control diet are given in Table 2. Whole-body retention was only 0-65 % of the ingested dose compared with the value of 10% that has been reported for human adults (Kehoe, 1961).…”

Section: Introductionmentioning

confidence: 62%

“…Tompsett (1939) found no relationship between dietary fat and lead absorption but Weyrauch and Necke (1932) reported an increase in lead absorption with increased dietary fat. The common food additives, 'alginates', have been reported to diminish lead uptake from the intestine of newborn rats (Kostial, Simonovic and Pisonic, 1971a) but this has not been confirmed (Harrison et al, 1969;Carr, Nolan and Durakovic, 1969).…”

Section: Introductionmentioning

confidence: 99%

The influence of nutritional factors on lead absorption

Barltrop

Khoo

1975

Postgraduate Medical Journal

138

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SummaryThe nutritional factors which affect lead absorption have been studied. Synthetic diets of known composition were compounded to contain 0-075% Pb as PbCl2 labelled with 203Pb. Rats were exposed to lead for periods of 48 hr. The dietary intake was then measured and the absorption of lead determined by means of a whole-body counter. Lead absorption was increased by high fat, low mineral, low protein and high protein diets but was decreased by high mineral diet. Low fat, low fibre, high fibre, low vitamin and high vitamin diets had no effects on lead absorption.

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“…High dietary calcium inhibits lead absorption by rats (183). At the cellular level, calcium also appears to be protective, for example against impairment of the myoneural junction by lead (184).…”

Section: Interactions Between Calcium and Leadmentioning

confidence: 98%

Factors influencing metabolism and toxicity of metals: a consensus report

1978

Environ Health Perspect

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Reduction of lead absorption from the intestine in newborn rats

Cited by 43 publications

References 7 publications

Influence of age on metal metabolism and toxicity.

Influence of age on metal metabolism and toxicity.

The influence of nutritional factors on lead absorption

Factors influencing metabolism and toxicity of metals: a consensus report

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