1 Twenty three adults ingested 203Pb as lead acetate on the 12th hour of a 19 h fast. Retention measured 7 days later in a whole-body counter was 61% and whole-body turnover rates suggested that initial uptake had been considerably greater. 2 Balanced meals eaten with 203Pb reduced lead uptake to 4% and the influence of the food lasted for up to 3 h. The effects of phytate, ethylenediaminetetra acetate (EDTA), caffeine, alcohol, glucose, a liquid meal and a light snack were tested separately with intermediate results. 3 The effect of a meal was probably largely due to its content of calcium and phosphate salts but lead uptake was probably further reduced by phytate which is plentiful in whole cereals and it was probably increased by a factor in milk. Uptake with skimmed milk was the same as with whole milk and we suggested that the factor was not fat. Comestibles with low mineral and phytate contents reduced lead uptake by intermediate amounts, possibly by stimulation of digestive secretions. 4 The avid uptake of lead during a fast, the large reduction of lead uptake with meals and the likelihood of variations in gastric-emptying rates and dietary habits may be major causes of variation in body burdens of lead in the population.

1. The transport of the lead cation has been investigated using the everted sac preparation of Wilson & Wiseman (1954). 2. Only a small percentage of lead was transported into the serosal compartment but there was a rapid and massive uptake onto the tissue. There was no significant difference in the amount of lead cations transported across different regions of the small intestine. 3. Both the rate of transport into the serosal compartment and the tissue uptake increased linearly with increasing concentration of the lead cation, from 10−7 M to 5 × 10−5 M. Little evidence for saturation of serosal transport or tissue uptake was found. 4. Lead transport into the serosal compartment appeared to be related to water movement, but was little affected by changes in glucose concentration and temperature. 5. It is concluded that lead is transported into the serosal space by a process of passive diffusion linked to water transport. 6. The interaction between lead ions and the intestinal tissue was extremely tenacious and displayed characteristics of covalent bonding. 7. It is suggested that the lead cation interacts with tissue phosphate ions thus removing lead ions from the transport pool. Chelation of lead to form a neutral species reduces this interaction and also promotes transport.

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a Ann. Reports of H.M. Insp. Factories on Ind. Health. a Metallgelellscha f t , 1 93 8-1 959. Europe U.S.A.

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