Research & reports
Peer-reviewed research and reports on community urban agriculture, food education, composting, welfare and more.
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Critical findings
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Heavy metal accumulation in Amaranthus hybridus and Ocimum gratissimum cultivated on automobile workshop soils in Ekiti Nigeria and associated human health risks
2026Amos Tomiwa Afolabi, Bridget O. Odiyi, Oluwasheun Johannah Ojeniyi · Discover Soil. · Nigeria (Ado-Ekiti)
A study in Ado-Ekiti, Nigeria, investigated heavy metal accumulation in Amaranthus hybridus and Ocimum gratissimum grown on soils from two automobile workshops. A. hybridus accumulated higher metal concentrations than O. gratissimum, with stems showing greater accumulation than leaves. While non-carcinogenic and total cancer risks were within acceptable limits, children showed higher vulnerability, indicating that continuous monitoring and soil remediation are essential for sustainable urban agriculture in these contaminated areas.
Contamination & food safetyHealthPlastic debris facilitates the survival of multidrug-resistant bacterial pathogens in an urban agricultural environment
2026Michael J. Ormsby, Luke Woodford, James Joseph Mwesiga, Winnie Ernest, Dativa J. Shilla, Daniel Abel Shilla, Richard S. Quilliam · Environmental Pollution · Africa
This study investigated plastic debris as a reservoir for multidrug-resistant (MDR) enteric bacterial pathogens at two peri-urban agricultural sites in Dar es Salaam, Tanzania. Analysis of 140 environmental samples (soil, water, vegetation, plastic debris) showed higher concentrations of culturable pathogens on plastic debris, with presumptive E. coli loads of ~1 × 10^3 CFU per piece. Plastic debris harbored a greater proportion of MDR strains, including E. coli and K. pneumoniae resistant to critically important antimicrobials, indicating that plastic waste facilitates the survival of MDR pathogens and poses health risks.
Contamination & food safetyHealthFood sovereignty & justicePeri-urban agricultureAssessment of Municipal Solid Waste Compost Used In Urban Agriculture and Its’ Potential Public Health Impacts In Katsina City, Nigeria.
2025Aminu Zakariyau, Murtala Rabiu · International Journal of Advances in Engineering and Management · Nigeria (Katsina City)
The potential ecotoxicological impacts of municipal solid waste compost (MSWC) on soil, plants, and humans in urban Katsina, Nigeria, were assessed. Analysis of soil mixtures and plant biomass (maize and beans) revealed high phytotoxicity in beans, while maize considered MSWC as phytonutrients. No statistical difference in non-biodegradable substance concentrations in soils and plants was found, and ecological risk index (ERI) indicated low risk; however, Target Hazard Quotients (THQ) suggested a likelihood of non-carcinogenic effects to the ecosystem.
Contamination & food safetyCompostHealthOrganic cycleUncontrolled urban vegetable farming poses public health risks in Ethiopia
2025Taffere Addis, Sisay Ketema, Abayneh Melaku · Frontiers in Water · Ethiopia (Addis Ababa)
This study in Addis Ababa, Ethiopia, investigated trace metal levels in sediment, soil, and irrigated vegetables from farms along the Akaki River, evaluating public health risks. Sediment levels of arsenic, chromium, copper, nickel, lead, and zinc exceeded threshold effect levels. Soil levels of arsenic, chromium, copper, manganese, and zinc exceeded typical world soil values, with nickel at one site exceeding EEC limits for agricultural soils. Critically, arsenic, lead, and zinc levels in some vegetable samples were above WHO allowable limits, despite soil levels being acceptable, and cadmium was the most accumulated metal in vegetables.
Contamination & food safetyHealthUrban–rural linkageCadmium and lead pollution in environmental and food matrices in Kakamega Town of Kenya highlighting risks in rapidly urbanizing regions of Africa
2025Doreen N. Meso, Enos W. Wambu, Gelas Simiyu, Shem M. Mwasi, Thomas Munyao · Discover Environment · Kenya (Kakamega Town)
This study assessed heavy metal pollution in agricultural soils, water, and pumpkin leaves from 21 sites across three zones in peri-urban Kakamega Town, Kenya. It found cadmium pollution in all water samples, and lead and nickel pollution in sections of soil and leafy vegetable samples. Lead pollution was linked to vehicular emissions near the town center, while cadmium enrichment in informal settlements implicated inadequate waste management. Sequential extraction showed 31–35% of soil cadmium was in exchangeable fractions, posing a risk of bioavailability, highlighting persistent heavy metal contamination with implications for public health, environmental sustainability, and agricultural productivity.
Contamination & food safetyHealthPeri-urban agricultureThe Health Burden of E-Waste: The Impact of E-Waste Dumping Sites on Child Mortality
2024Stefania Lovo, Samantha Rawlings · The World Bank Economic Review · Ghana, Nigeria
This study investigated the impact of e-waste dumping sites on neonatal and infant mortality, focusing on two major dumpsites in Ghana and Nigeria. Using a difference-in-differences approach, outcomes were compared for children born near and far from dumpsites before and after their creation. E-waste sites increased neonatal and and infant mortality for those living closer to the sites, with event studies suggesting effects emerge two to three years after site openings. There is suggestive evidence that contamination of water and of urban farming produce are among the drivers of the observed effects.
Contamination & food safetyHealthEconomicsAssessment of concentrations of heavy metals in three leafy vegetables irrigated with wastewater in Hadnet district, Mekelle, Ethiopia
2024Hailekiros Tadesse Tekle, Desta Berhe Sbhatu, Gebreselema Gebreyohannes · H2Open Journal · Ethiopia (Mekelle)
A study in Hadnet district, Mekelle, Ethiopia, assessed heavy metal concentrations in wastewater, spring water, and three leafy vegetables (lettuce, spinach, cauliflower). Wastewater samples from four experimental sites exceeded permissible limits for 4 out of 10 heavy metals (Cd, Cr, Cu, Mn), and spring water from a comparison site also exceeded limits for 4 metals (Al, As, Cd, Cu). Leafy vegetables grown in the least contaminated experimental site showed high concentrations for 6-7 out of 10 heavy metals, with lettuce and spinach having elevated levels of As and Al, respectively. The study concluded that the wastewater used for irrigation is not safe, the farm soils may have accumulated significant heavy metals, and the cultivated vegetables are highly contaminated, necessitating regulation of wastewater use for irrigation.
Contamination & food safetyHealthPeri-urban agricultureHeavy metals and trace elements contamination risks in peri-urban agricultural soils in Nairobi city catchment, Kenya
2023Arcadius Martinien Agassin Ahogle, Sammy Letema, Gertrud Schaab, Veronica Ngure, Abraham R. Mwesigye, Nicholas Kibet Korir · Frontiers in Soil Science · Kenya (Nairobi)
This study assessed heavy metal and trace element contamination risks in peri-urban farmlands in Nairobi city catchment, Kenya, by analyzing 60 soil samples from ten vegetable farming zones. Results showed elevated concentrations of elements including As, Cd, Mn, Pb, and Zn, with some exceeding permissible agricultural thresholds. As, Cd, Hg, and Pb exhibited high ecological risks, with Cd contributing 46-66% of the overall risk.
Contamination & food safetyPeri-urban agricultureHealthPrevalence and risk factors of childhood diarrhea among wastewater irrigating urban farming households in Addis Ababa
2023Adane Sirage Ali, Sirak Robele Gari, M.L. Goodson, Claire Walsh, Bitew K. Dessie, Argaw Ambelu · PLoS ONE · Ethiopia
This cross-sectional study investigated the prevalence and risk factors of diarrhea among children under five in 402 wastewater irrigation farming households in Addis Ababa, Ethiopia, from November 2021 to February 2022. The overall prevalence of diarrheal cases in children under five was 22.3%. Diarrhea was strongly associated with wastewater-related occupational exposure factors, including body washing with irrigation water, contaminated cloth with irrigation water, use of protective clothing during farm work, use of farm work cloths at home, and bringing unwashed farm tools home.
Contamination & food safetyHealthAssessment of Microbial Contamination in the Infulene River Basin, Mozambique
2023Clemêncio Nhantumbo, Nídia Cangi Vaz, Mery Rodrigues, Cândido Manuel, Sífia Rapulua, Jéssica Langa, Hélio Nhantumbo, Dominic Joaquim, Michaque Dosse, José João Sumbana, Ricardo Santos, Sílvia Monteiro, Dinis Juízo · Water · Mozambique
A study investigated fecal microbial contamination levels in river water, drainage water, and drinking water in the Infulene River Basin, Mozambique. Samples from the Infulene River and drainage showed 82% positive for Total Coliforms and 61% for Escherichia coli, while drinking water samples were 63% positive for Total Coliforms and 23% for Escherichia coli. The study confirmed a high vulnerability to microbial contamination across all investigated sources due to poor sanitation and a lack of drainage infrastructure.
Contamination & food safetyHealthWastewater governance in the upstream catchment of the Awash Basin, Ethiopia: challenges and opportunities for better accountability
2023Yosef Abebe, Mulugeta Gashaw, Asenake Kefale, Tim Brewer · Water Reuse · Ethiopia
A study on wastewater governance in the upstream catchment of the Awash Basin, Ethiopia, found that untreated wastewater discharged from industries is polluting rivers and the surrounding environment. Regulatory bodies have done little to enforce rules and directives for wastewater regulation, and due to poor implementation of laws, urban agriculture is expanding without concern for its negative health and socioeconomic impacts.
Contamination & food safetyHealthPolicyEconomicsClimate changeHeavy metal occurrence within urban agriculture practices in eastern zones of Nairobi city
2023Njenga John Ng’ang’a, Mukundi John Bosco, Masinde Peter Wasike, Kihurani Agnes Wanjiru · Journal of Agriculture Science and Technology · Kenya (Nairobi)
A study in Nairobi's eastern zone assessed heavy metal occurrence in urban farm inputs and food crops (tomatoes, arrowroots, kales). Cadmium, manganese, lead, and zinc concentrations were analyzed in soil, water, and crop samples. The study found that heavy metal contents, particularly cadmium, manganese, lead, and zinc, were above allowable limits in several crops, and based on FAO/WHO standards, were high for health concern.
Contamination & food safetyHealthUrban–rural linkageAssessment of Quality of Wastewater Being Used in Irrigating Soils under Urban Agriculture in Zaria Urban Area
2022Sani Abubakar Mashi, Samuel Yakubu, Sofia Yuniar Sani · Asian Research Journal of Agriculture · Africa
A study in the Kubanni basin of Zaria, Africa, evaluated the quality of wastewater used for irrigating urban agriculture soils. The wastewater contained arsenic, iron, chromium, copper, zinc, manganese, and lead. Although concentrations were generally below Nigeria's permissible limits for irrigation, the study noted the metals' tendency to accumulate in soils, raising concerns about potential heavy metal buildup in irrigated soils and crops.
Contamination & food safetyHealthOrganic cycleChromium Laden Soil, Water, and Vegetables nearby Tanning Industries: Speciation and Spatial Distribution
2021Adugnaw Maru Gezahegn, Fekadu Fufa, Esayas Alemayehu, Abebe Beyene · Journal of Chemistry · Ethiopia (Modjo city)
This study investigated the spatial distribution and speciation of chromium in water, soil, and edible plants in tannery-contaminated areas of Modjo city, Ethiopia. Total chromium in the Modjo River was 20.6 mg L−1 upstream, and soil Cr (III) and Cr (VI) concentrations were found to be higher than guideline values. Chromium concentrations in edible plants were also significantly higher than in control areas, with roots accumulating more chromium than leaves and fruits. It was concluded that water, soil, and edible plants in this area contain chromium concentrations higher than recommended for a healthy environment and human consumption.
Contamination & food safetyHealthUrban–rural linkagePredicting the Toxicities of Ternary Mixtures of two Metals and Sodium Dodecyl Sulfate to Serratia marcescens (SerEW01) from Otamiri River Water
2020Reuben Nwoye Okechi, Edna Ifeoma Chukwura, Christian Okechukwu Nweke · Journal of Advances in Microbiology · Nigeria (Owerri)
This study, conducted in Owerri, Nigeria from June to December 2019, evaluated the interactive toxic effects of ternary mixtures of sodium dodecyl sulfate (SDS) and divalent metals on Serratia marcescens (SerEW01) from the Otamiri River, a source for urban farming. The study found that both concentration addition (CA) and independent action (IA) models predicted lower toxicities compared to experimentally observed data. The Toxic Index and Model Deviation Ratio indicated a synergistic interaction of SDS and metal ions, resulting in higher combined toxicities than predicted, posing environmental hazards due to co-contamination.
Contamination & food safetyHealthFoodborne illness prevention in Debre Berhan, Ethiopia: Preliminary efforts to understand household agricultural practices
2020Hillary A. Craddock, Elisabeth Fost Maring, Stephanie Grutzmacher · African Journal of Food Agriculture Nutrition and Development · Ethiopia
A mixed-methods pilot survey of 21 teachers and parents in Debre Berhan, Ethiopia, investigated household agricultural practices to understand foodborne illness risks. The study found that half of respondents using manure applied uncomposted manure as fertilizer, and many kept multiple animal species. This suggests a high risk of pathogen exposure for children and adults through contact with uncomposted manure and animals.
Contamination & food safetyHealthCompostOrganic cyclePratiques phytosanitaires en agriculture périurbaine et contamination des denrées par les pesticides : cas des maraîchers de Port-Bouët (Abidjan)
2019· Journal of Animal and Plant Sciences (J Anim Plant Sci ) ISSN 2071 – 7024 · Africa
A study in Port-Bouët, Abidjan, examined market gardeners' phytosanitary practices and pesticide residue incidence on lettuce. It found that 39.6% of pesticides used were not recommended for market gardening, 86.84% of gardeners did not protect themselves during application, and 80.26% did not observe pre-harvest intervals. Consequently, 93.33% of lettuce samples did not comply with Codex Alimentarius and EU standards due to high pesticide residue contamination.
Contamination & food safetyPeri-urban agricultureHealthFarmers' Perception, Willingness and Capacity in Utilization of Household Sewage Sludge as Organic Resources for Peri-Urban Agriculture around Jos Nigeria
2019Cosmos C. Alamanjo, Abimbola O. Adepoju, H. Martin, R.N. Baines · Zenodo (CERN European Organization for Nuclear Research) · Nigeria (Jos)
This mixed-methods study investigated farmers' perceptions, willingness, and capacity to use household sewage sludge as organic resources for peri-urban agriculture around Jos, Nigeria. Farmers were found to use a complex mix of fertilizers and were keen to utilize household sewage sludge for soil fertility, though constrained by accessibility. A critical finding was that household sewage sludge observed in the field is heterogeneous due to its proximity to urban refuse disposal, raising concerns for possible cross-contamination of pollutants and indicating a lack of extension guidance.
Contamination & food safetyPeri-urban agricultureOrganic cycleCompostHealthComparison of metallic trace elements accumulation capacities in three market garden species, lettuce (Lactuva sativa L.), spinach (Spinacia oleracea L.) and amaranth (Amaranthus paniculatus L.), grown on agricultural sites in the city of Abidjan (Côte d’Ivoire)
2019Kouassi Joseph Kouakou, Ahoua Edmond Sika, Seu Jonathan Gogbeu, Koffi Bertin Yao, M. Bounakhla, Denézon Odette Dogbo, Yves‐Alain Bekro · · Africa
This study compared the accumulation potential of five trace metals (cadmium, copper, lead, zinc, and nickel) in lettuce, spinach, and amaranth grown at market gardening sites in Abidjan, Côte d’Ivoire. Using principal components analysis, it was found that lettuce had a greater capacity for accumulating these metals compared to spinach and amaranth. Amaranth and spinach from the three sites showed nearly identical metal accumulation capacities.
Contamination & food safetyHealthFood sovereignty & justiceMicrobiological quality of lettuce (Lactuca sativa) irrigated with wastewater in Addis Ababa, Ethiopia and effect of green salads washing methods
2017Desta Woldetsadik, Pay Drechsel, Bernard Keraita, Fisseha Itanna, Berhanu Erko, Heluf Gebrekidan · International Journal of Food Contamination · Ethiopia (Addis Ababa)
An assessment in Addis Ababa, Ethiopia, analyzed 210 lettuce and 90 irrigation water samples for faecal coliform and helminth eggs. Faecal coliform levels ranged from 4.29-5.61 log10 MPN 100 ml−1 in water and 3.46-5.03 log10 MPN 100 g−1 on lettuce, exceeding WHO recommendations. Helminth eggs were detected in 80% of water and 61% of lettuce samples, also exceeding standards. While washing methods reduced contamination, levels remained in a potential risk range.
Contamination & food safetyHealthEvaluating peri-urban market gardening and shallow well quality for irrigation: a case study from Lagos, Nigeria
2016Isaiah Sewanu Akoteyon, Adeyemi Davidson Aromolaran · International Journal of Environment and Sustainable Development · Nigeria (Lagos)
This study evaluated peri-urban market gardening and shallow well water quality for irrigation in Lagos, Nigeria. It found that the mean values of bicarbonate, calcium, and pH in shallow wells exceeded detection levels in 66.7%, 60%, and 53.3% of samples, respectively. Salinity and sodium hazard patterns showed that approximately 66.7% of shallow wells had low salinity, 26.7% medium, and 6.7% high.
Contamination & food safetyPeri-urban agricultureHealthFood sovereignty & justiceUrban farming as a possible source of trace metals in human diets
2016Joshua Oluwole Olowoyo, Gladness Nteboheng Lion · South African Journal of Science · South Africa
This review reports on the concentrations of trace metals in crops, including leafy vegetables, harvested from various urban areas. It highlights the presence of trace metals in leafy vegetables and discusses various pathways of uptake, possible health risks associated with urban farming, and morphological and physiological impacts of trace metals in leafy vegetables.
Contamination & food safetyHealthPeri-urban agricultureUrban–rural linkageMicrobiological and Physicochemical Evaluation of Jakara Canal Wastewater Used for Irrigation in Kano
2015M. G. Dahiru, Onaiwu Idahosa Enabulele · · Nigeria (Kano)
Microbiological and physicochemical parameters of urban wastewater from the Jakara Canal in Kano were analyzed to assess its potential for irrigation. Mean fecal coliform counts ranged from 64.43 ± 63.20 MPN 100/ml to 216.85 ± 350.16 MPN 100/ml, increasing along the canal. All physicochemical parameters were within FEPA and WHO/FAO acceptable limits, but conductivity needed monitoring to avoid salinity.
Contamination & food safetyHealthOrganic cycleUrban–rural linkageManagement of poultry waste and its implications on urban vegetable production in Metropolitan Lagos
2015Vide Adedayo · Journal of Research in National Development · Nigeria (Lagos)
This study investigated poultry waste management in urban vegetable farms in Metropolitan Lagos from an ecosystem to human health perspective. Using a transdisciplinary approach, community participation, and socio-cultural, physiochemical, microbiological, and clinical information, the research revealed negative impacts and health problems associated with poultry waste management due to poor storage, composting, and packaging techniques. Consequently, adverse effects on users were identified.
Contamination & food safetyOrganic cycleHealthRisques de fièvres typhoïdes et paratyphoïdes liés à l’utilisation des eaux usées en agriculture urbaine et périurbaine : cas du maraîchage dans la ville de Parakou (Bénin)
2014Joseph Agossou, Léonard Afouda, Julien Didier Adédémy, Alphonse Noudamadjo, Catherine N’da Tido, Emanliikpon Sylvain Ahohoui, Pierre G. Tovihoudji, Farouk Mazou, Benjami Fayomi, Simon Akpona, Sikiratou Adéothy-Koumakpaï, B Ayivi · Environnement Risques & Sante · Benin (Parakou)
This study analyzed the bacteriological and parasitic load in wastewater and market garden products from five major production sites in Parakou, Benin, where farmers use wastewater for irrigation. High concentrations of fecal coliforms, Escherichia coli, Salmonella enterica, Shigella spp., Entamoeba coli, Giardia intestinalis cysts, and helminth eggs were found in irrigation water, vegetables, and farmers' stools. The use of wastewater resulted in high contamination of vegetables, particularly cabbage, large lettuce, and carrot leaves, by fecal coliforms, Salmonella enterica, and Escherichia coli.
Contamination & food safetyHealthPeri-urban agriculture