Health Risk Assessment on Selected Essential and Non-Essential Elements in Food Crops Grown in Kibera Slum, Nairobi-Kenya

Abstract

Peri-urban agriculture of food crops is practiced in many slum areas in developing countries. This often uses waste water whose levels of essential and non-essential elements are largely unknown but would be feared to contaminate soils, consequently exposing man to associated health risks. Inhabitants in Kibera slum, Nairobi City practice these growing kales, amaranthus, arro-wroots, and spinach. Health risk assessment was done using daily intake of metals (DIM), target hazard quotient (THQ) and incremental lifetime cancer risk (ILCR). Atomic absorption spectroscopy was employed for elemental analysis. The levels of essential elements ranged as follows; Mn 91.04-374.44, Mg 261.28-532.96, Fe 350.74-1273.68, and Zn 1.18-6.3 µg/g per dry weight were found to be below the recommended limits by FAO/WHO. Non-essential elements ranged as follows; Cr 1.15-4.32 and Pb 0.14-0.91 µg/g above the EU recommendation. DIM of Fe 5.81-27.61 and Mn 1.97-8.12 µg/g is above the recommended daily intake amounts. THQ values for Mn and Fe were more than unit. THQ values for non-essential elements were generally below unit. ILCR showed that from lead alone 73 people (0.043% of 0.17M residents) are likely to develop cancer. There are foreseen health risks associated with consumption of food crops grown in Kibera slum that requires immediate address.