Evaluation Of Lead And Cadmium In Selected Kenyan Population And Sources Including Determination Of Trace Elements In Consumable Clays Using Atomic Absorption Method

Abstract

The analysis was done by using Atomic Absorption Method. The evaluation of lead and cadmium in the general Kenyan population was done using blood samples collected from Nairobi Hospital, Kiambu Hospital and Chemelil Sugar Factory’s Dispensary. Only 5% of the Nairobi samples, 2% of the Kiambu and Chemelil samples showed the presence of lead, with highest value of 256.70 Ugdl"^. For the majority of the samples (96%), the lead levels were below 20 Ugdl_i, which actually lies within the ’normal' levels of lead with upper limit of about 40 Ugdl-^. On the other hand, 32% of the Nairobi samples, 18% of the Kiambu samples and 35% of the Chemelil samples indicated the presence of cadmium (highest 32.30 Ugdl'1), suggesting that the metal is becoming more abundant in the environment. The rest of the samples had levels below 1 ugdl-^. The mean lead levels ranged from 16-46 Ugg-1 in the pots and 16-36 ^gg”^ in the soils (used to prepare the pots); cadmium levels ranged from 0.50-0.90 Ugg-1 in the pots and also the same amount in the soils. Therefore, levels of these metals in the pots and soils were similar, suggesting that heating during pot preparation and also cooking does not affect the levels of the metals (Pb, Cd) in the pots significantly. -xi- Studies done on the leaching of these metals during cooking of acidic (eg. pH 2.0) food stuffs showed that very little amounts get removed. Therefore, the use of local pottery in cooking does not contribute significantly to lead and cadmium toxicity in this country. Clays consumed by pregnant women in Kenya, that is, volcanic tuff and mahti, contain very high levels of aluminium (30,156-49,803 mg kg1) and iron (19,117-40,655 mg kg-1) and also appreciable amounts of cadmium (0.46-0.78 mgkg-1), copper (4.32-26.25 mgkg-*), cobalt (4.87-15.61 mgkg-1), Chromium (7.34-117.27 mgkg-1), lead (20.41-24.52 mgkg-1), manganese (687.1-974.44 mgkg-1). nickel (20.13-23.38 mgkg'1) and zinc (38.57-102.39 mgkg-1). Evaluation of lead and cadmium in cigarettes showed that cigarette tobacco contains high levels of these metals. The lead levels ranged from 6.52-8.82 ugg -1 and cadmium levels from 0.84-1.25 ugg- 1. Therefore smoking is an important source of lead and cadmium in the environment.