Levels of Lead and Cadmium in some food crops and dietary intakes from dining hall diets in areas of Kabwe and Lusaka

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.