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

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.

Heavy metal concentration and health risk assessment in commonly sold vegetables in Dhaka city market

“…The metal concentrations in the leafy vegetables were slightly higher than fruit vegetables could probably be ascribed to its high foliar surface area and industrial activities. Some common vegetables including Amaranthus species are proficient of accuring high heavy metals levels from contaminated irrigating water or growing soil as reported earlier (Kacholi and Sahu, 2018). These findings suggests that many contaminated vegetables are sold in Kawran Bazar city market (Dhaka, Bangladesh) which are not safe for human consumption.…”

“…The Cr toxicity affects many organs in humans, such as liver, kidney, lungs and spleen, causing severe biochemical defects and cancer. High Average Daily Intake (ADI) of heavy metals has been also reported in Bangladesh (Kacholi and Sahu, 2018).…”

“…The sources of higher metal contents in the vegetables could be attributed to the location of the field, which is situated along the hectic road traffic/irrigated with contaminated water/use of agrochemicals or disposal of industrial wastes and effluents into the agricultural fields etc. (Kacholi and Sahu, 2018). Heavy metals like Cu and Zn in the field could be ascribed to agricultural products that were added to the soil as fertilizer, while Pb is a contaminant that is known to emanate from traffic activities, such as fuel combustion, lubricating oil, tire and brake wear, road abrasion and road runoff, which in one way or the other can impact roadside grown vegetables (Kacholi and Sahu, 2018).…”

“…(Kacholi and Sahu, 2018). Heavy metals like Cu and Zn in the field could be ascribed to agricultural products that were added to the soil as fertilizer, while Pb is a contaminant that is known to emanate from traffic activities, such as fuel combustion, lubricating oil, tire and brake wear, road abrasion and road runoff, which in one way or the other can impact roadside grown vegetables (Kacholi and Sahu, 2018).…”

Variation of heavy metal contamination between mushroom species in the Copperbelt province, Zambia: are the people at risk?

“…Research has shown that high concentrations of Cd and Pb in the soil have led to higher concentrations of these metals in mushrooms growing on such soils . Essential elements including Zn, Cu and Fe play a significant role in the physiology of plants and animals as long as they are within the recommended limits, but metals such as Pb, Cd, Cr and Hg are toxic environmental pollutants that pose health risks. Significantly lower concentrations of metals have been detected in A. biosporus , Polyporus frondosis and Armillariella mellea despite these mushrooms growing in highly polluted soils .…”