Estimated dietary intake of lead and cadmium and their concentration in blood

Dietary intake of lead and cadmium and the concentration of Pb and Cd in blood were determined for 42 non-smoking subjects not occupationally exposed to Pb or Cd. The aim of the study was to analyze: (i) the relation between calculated dietary intake of Pb and Cd and the concentration of these metals in blood; and (ii) the methodological problems associated with these two measurements of exposure. The mean dietary intakes of Cd and Pb were 14.5 (SD, 3.1) and 52.9 (SD, 17.9) micrograms day-1, respectively. The concentrations of Pb and Cd in blood were 0.28 mumol l-1 (SD, 0.12) and less than 0.1 microgram l-1, respectively. The relation between dietary intake and concentration in blood was similar to that found in other countries. However, the distributions of these two variables were quite different. This suggests that dietary intake does not accurately reflect the concentration of lead in blood. The methodological problems associated with estimating the dietary intake of toxic metals were: mistakes in keeping food diaries; errors in transferring data from diaries to the computer; invalid food composition or recipe data in the data base used in the calculations. The concentration of Pb and Cd in blood is not necessarily a good indicator of exposure, since only a small proportion of the total body burden is in the blood, and interactions of Pb and Cd with other food constituents during absorption are possible.