Analysis of heavy metals and pathogen levels in vegetables cultivated using selected water bodies in urban areas of the Greater Accra Metropolis of Ghana

Shine Francis Gbedemah; Alain Attasse Gbeasor; Gideon Selorm Hosu-Porbley; Louis Kusi Frimpong; Richard Amfo-Otu; Selase Kofi Adanu; Eric Kofi Doe

doi:10.1016/j.heliyon.2024.e27924

Analysis of heavy metals and pathogen levels in vegetables cultivated using selected water bodies in urban areas of the Greater Accra Metropolis of Ghana

Heliyon. 2024 Mar 20;10(7):e27924. doi: 10.1016/j.heliyon.2024.e27924. eCollection 2024 Apr 15.

Authors

Shine Francis Gbedemah¹, Alain Attasse Gbeasor², Gideon Selorm Hosu-Porbley³, Louis Kusi Frimpong¹, Richard Amfo-Otu⁴, Selase Kofi Adanu⁵, Eric Kofi Doe⁶

Affiliations

¹ Department of Geography and Earth Sciences, University of Environment and Sustainable Development, Somanya, Eastern Region, Ghana.
² Ace Technologies Ghana Limited, Accra, Ghana.
³ Centre for Migration Studies, University of Ghana, Accra, Ghana.
⁴ Department of Environment and Public Health, University of Environment and Sustainable Development, Somanya, Eastern Region, Ghana.
⁵ Department of Environmental Science, Ho Technical University, P. O. Box HP 217, Ho, Ghana.
⁶ Department of Geography and Resource Development, University of Ghana, Accra, Ghana.

Abstract

Open-surfaced water sources have been used to irrigate vegetable farms in cities. Open-surface water often contains unmonitored concentrations of health-threatening contaminants that pose health risks, especially when used to produce vegetables for human consumption. However, information on levels of heavy metals and faecal coliform bacteria in such vegetables in selected sites, especially in Greater Accra Metropolitan Area (GAMA) of Ghana is rare. This study examines the levels of heavy metals and faecal coliform in two vegetables-lettuce and bell pepper - that were cultivated using open-surface wastewater from drains and constructed reservoirs at different locations of the GAMA. Using concurrent mixed methods, questionnaires were administered to 67 vegetable farmers, followed by the collection of vegetable samples from three urban farm sites, Haatso and Dzorwulu and Weija irrigation scheme site (WISS) for laboratory analysis. The concentrations of Lead (Pb), Mercury (Hg) and Cadmium (Cd) were determined using atomic absorption spectroscopy after microwave digestion of the vegetables while total faecal coliform was quantified using MacConkey-Endo broth method. The results from all three sites showed that the concentrations of Cd (=0.001 μg/mg) and Pb (=0.005 μg/mg) in lettuce were within the World Health Organization's (WHO) permissible levels. However, the Hg (≥0.309 μg/mg) and faecal coliform (>5 count/100 ml) in the vegetables from all three sites exceeded the WHO permissible limits. Therefore, consumers of vegetables from such urban farms are exposed to health risks associated with Hg and faecal coliforms. There is the need to intensify education on the health risks of consuming vegetables produced from open-surface water sources from the observed sites. The enforcement of existing phytosanitary standards to enhance food safety and the quality of urban vegetables is also recommended.

Keywords: Faecal coliform; GAMA; Irrigated farmlands; Lettuce and Bell pepper; Polluted water; Urban farming.