Levels and Health Risk Assessment of Heavy Metals in Soil, Water, and Vegetables of Dar es Salaam, Tanzania

David Sylvester Kacholi,Minati Sahu

doi:10.1155/2018/1402674

Abstract

This study assesses heavy metals’ levels in water, soil, and vegetables (Ipomoea batatas (Matembele), Amaranthus hybridus (Mchicha), Abelmoschus esculentus (Bamia), and Solanum melongena (Bilinganya)) from the Chang’ombe police garden located in Temeke district, Tanzania. Also, it examines potential health risks from consumption of the vegetables. The samples of soils, water, and vegetables were randomly collected, processed, and analyzed for heavy metals using Atomic Absorption Spectrophotometry. The heavy metals’ levels in soil, water, and vegetables were in the order of Fe > Zn > Pb > Cu. Among the vegetables, I. batatas had highest heavy metal content followed by A. hybridus, S. melongena, and A. esculentus. The average daily intake for Pb (63 mg/person/day) was above the permissible maximum tolerable daily intake of 0.21 mg/person/day endorsed by WHO/FAO. Hazard quotient of Pb for I. batatas (7.12) and A. hybridus (2.46) as well as the hazard indices of I. batatas (7.99) and A. hybridus (2.88) exceeded unity, signifying presence of health risks from consumption of the vegetables. This study recommends regular monitoring of heavy metals in soils, water, and foodstuffs to prevent excessive accrual in food chain.

Highlights

Heavy metals pollution is a menace to our environment as they are foremost contaminating agents of our food supply, especially vegetables [1]
These findings indicate that Cu has higher transferability, while I. batatas is having high absorbing capability followed by A. hybridus
The findings show that hazard quotient (HQ) values of all heavy metals were

Summary

Introduction

Heavy metals pollution is a menace to our environment as they are foremost contaminating agents of our food supply, especially vegetables [1]. A number of studies have shown that some common vegetables including Amaranthus species are proficient of accruing high heavy metals levels from contaminated irrigating water or growing soil [25, 26]. The present study assesses heavy metals’ levels (Cu, Zn, Fe, and Pb) in growing soil, irrigating water, and four popularly consumed vegetables, Amaranthus hybridus, Ipomoea batatas, Solanum melongena, and Abelmoschus esculentus, from the Chang’ombe police garden. It calculates the soil-plant transfer coefficients of heavy metals for each vegetable, heavy metal average daily intake rate, hazard quotient (HQ), and hazard index (HI). The study hypothesizes that heavy metals’ levels are above established standards by WHO/FAO in all the studied compartments

Experimental

Sample Preparation and Analysis

Results and Discussion

Conclusion and Recommendations