HEAVY METAL (CU, ZN, CD AND PB) CONTAMINATION OF INDIGENOUS GREEN VEGETABLES IN ELDORET TOWN AND THEIR HEALTH IMPLICATIONS TO CONSUMERS

Abstract

The crops that are grown and sold could be exposed to toxic substances due to wide spread contamination of

water, air and soils by environmental pollutants. A single source of contamination can have serious effects on

human health. This study assessed the levels of selected heavy metals; Lead (Pb), Cadmium (Cd), Copper (Cu),

and Zinc (Zn) in indigenous green vegetables Solanum nigrum, Cleome gynandra and Amaranthus blitum sold

in Eldoret municipality. Samples were collected from sampling stations, Eldoret municipal market, estates and

supermarkets in polythene bags twice a month for three months. Analysis of heavy metals was determined in

the laboratory using atomic absorption spectrophotometer (AAS-Varian 200 model). The Provisional Tolerable

Daily Intake (PTDI) values were calculated to assess health risk implications. The results show high concentra

tion levels of Pb and Cd in the indigenous vegetables in all the sampling sites. Concentrations of heavy metals

in studied markets within Eldoret showed that, mean Zn concentration ranged from 0.16µg /kg at municipal

market to 3.99 µg/kg DW at Langas, mean Pb concentration ranged from of 0.00µg/kg DW at municipal market

to 1.23µg/kg dw at supermarket. Copper ranged from 0.01µg/kg at Langas to 1.20µg/kg DW at Huruma while

Cd ranged between 0.05µg/kg at supermarket to 1.70µg/kg DW at Huruma. A single washing of the samples

showed decline of heavy metals concentrations up to 30%.The calculated Pb and Cd PTDI values for unwashed

vegetables in the range of the FAO/WHO recommended values (214µg and 60µg respectively) indicating a

potential health risk to consumers. The study concludes that atmospheric depositions can elevate the levels of

heavy metals in vegetables during marketing having potential health hazards to consumers. Washing of veg

etables with clean water was a very effective and easy way of decontaminating the metal pollution as it reduced

the contamination levels. Consumption rates of the indigenous vegetables sold in Eldoret should fall within the

recommended limits to minimize health risks