Levels of Lead and Cadmium in some food crops and dietary intakes from dining hall diets in areas of Kabwe and Lusaka
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The content of cadmium and lead in raw food crops consisting of cabbage, rape, tomato and maize collected from selected retail markets, and in daily diets collected from selected school dining halls in Kabwe and Lusaka was determined. Separate analyte solutions were obtained after wet digestion of samples followed by extraction and precipitation for cadmium and lead respectively . Measurements were done using flame atomic absorption spectrophotometry technique. The range of concentrations in p.g/kg d.w. of raw food crops from Kabwe and Lusaka (and food crop with lowest and highest mean) were respectively for cadmium N.D.- 125 (Cabbage - rape) and N.D.- 264 (maize - tomato), and for lead N.D.- 1 974 (tomato - rape) and N.D.- 1 948 (maize - rape) with N.D. meaning "not detected" concentration. Calculations based on quantities assumed to be portions of total food consumed daily yielded W.I., in (ig/kg b.w. for a person weighing 60 kg, ranging from 0.01 to 0.196 for cadmium and from 0.11 to 0.351 for lead. These values represent 1.4 to 2.8% and 0.44 to 14% P.T.W.I.(Provisional Tolerable Weekly Intake) for cadmium and lead respectively. The mean concentration in jag/kg d.w. of food composites corresponding to the numbers of daily diets collected in a week from each selected institution was, for cadmium, between 6 and 12 with the exception of Saint Paul's Secondary School which showed N.D. as mean; and for lead, N.D. in all institutions except Saint Paul's Secondary School which had 462 as mean. The weekly dietary intake of food actually consumed, in }J.g/kg b.w. for a 60 kg man, was estimated to range between N.D.and 0.77 with most of the values on the higher limit for cadmium, and between N.D. and 29.6 with all the values on the lower limit except one for lead. These values represent N.D. to 11% and N.D. to 118.6% P.T.W.I, for cadmium and lead respectively. Sample recoveries, with values bracketed between 80% and 110%, demonstrated the accuracy of flame atomic absorption spectrophotometry technique. A comparison of the levels and W.I. of cadmium and lead reported hi this study for raw food crops and diets with legal limits were found to be within the normal range.
- Natural Sciences