Research & reports
Peer-reviewed research and reports on community urban agriculture, food education, composting, welfare and more.
Theme
Critical findings
17 results
Plastic 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 agricultureCadmium 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 agricultureAssessment 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 agricultureHealthPratiques 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 cycleCompostHealthEvaluating 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 linkageRisques 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 agricultureHeavy Metals and Physicochemical Properties of Soils in Kano Urban Agricultural Lands
2014UM Dawaki, A. U. Dikko, SS Noma, U. Aliyu · Nigerian Journal of Basic and Applied Sciences · Nigeria
A study investigated the total, exchangeable, and soluble concentrations of heavy metals (Cu, Cr, Ni, Zn, Pb, Cd) in urban agricultural soils along three rivers (Challawa, Jakara, and Watari) in Kano, Nigeria. Cadmium concentrations at Jakara and Challawa exceeded maximum allowable concentrations in soils. Heavy metal concentrations were found to be significantly higher in areas irrigated with industrial and domestic sewage (Challawa and Jakara) compared to the control site (Watari).
Contamination & food safetyHealthPeri-urban agricultureHeavy metal content of selected African leafy vegetables planted in urban and peri-urban Nairobi, Kenya
2014A. N. Mutune, M. A. Makobe, Mary Abukutsa‐Onyango · African Journal of Environmental Science and Technology · Kenya (Nairobi)
This study analyzed heavy metal content in 10 common African leafy vegetables and their rhizosphere soils from 25 sites along Nairobi Rivers, Kenya. While soil metal concentrations were generally within WHO/FAO permissible levels, except for some cadmium instances, all metals except copper in vegetables exceeded recommended limits at a few sites. This indicates potential heavy metal absorption from industrial and domestic effluent.
Contamination & food safetyHealthPeri-urban agricultureField assessment of cadmium, lead and zinc contamination of soils and leaf vegetables under urban and peri-urban agriculture in northern Nigeria
2012G. N. Egwu, John O. Agbenin · Archives of Agronomy and Soil Science · Nigeria
A study in northern Nigeria assessed cadmium, lead, and zinc contamination in soils and leaf vegetables (amaranthus, lettuce) irrigated with untreated wastewater. Total cadmium and zinc concentrations in soils exceeded safe limits, and lead and cadmium in edible portions of amaranthus and lettuce exceeded safe limits for human consumption by 7–17 times. The permissible limit for lead established for agricultural lands may not be suitable to ensure produce safety in urban and peri-urban agriculture in Kano.
Contamination & food safetyHealthPeri-urban agricultureConcentrations of Heavy Metals and Pesticide Residues in Leafy Vegetables and Implications for Peri-urban Farming in Nairobi, Kenya
2012Nancy Karanja, Mary Njenga, G.K. Mutua, Carl Johan Lagerkvist, E. Kutto, JJ Okello · Journal of Agriculture Food Systems and Community Development · Kenya (Nairobi)
A study in three peri-urban sites in Nairobi, Kenya, assessed heavy metal, nitrate, and pesticide residue levels in wastewater-irrigated kale. Elevated levels of boron, cobalt, chromium, copper, lead, zinc, and nickel were found in vegetables at two sites, with high soil loadings of nickel, arsenic, lead, chromium, copper, and zinc attributed to chicken manure. Pesticide residues of diazinon, cypermethrin, biternol, and profenofos exceeded permissible limits in kale at one site, suggesting consumers may ingest significant amounts of contaminants.
Contamination & food safetyHealthPeri-urban agricultureOverview on urban and peri-urban agriculture: definition, impact on human health, constraints and policy issues
2008Erastus K. Kang’ethe, Delia Grace, Thomas F. Randolph · East African Medical Journal · East Africa
This study synthesizes current knowledge on urban agriculture (UA) in East Africa, focusing on its human health impact. It identifies UA as an important source of food security, but notes that many zoonotic and food-borne diseases are associated with it, with a lack of evidence on human health impact and management. Major constraints include illegality and limited access to inputs and markets, indicating a need for more research to understand both positive and negative health impacts.
Contamination & food safetyHealthFood sovereignty & justicePolicyEconomicsPeri-urban agricultureLinking research, capacity building, and policy dialogue in support of informal irrigation in urban West Africa
2008Pay Drechsel, Olufunke Cofie, R. van Veenhuizen, Theophilus O. Larbi · Irrigation and Drainage · West Africa
Informal irrigation in urban and peri-urban agriculture (UPA) in West Africa offers benefits but is often hindered by water pollution, threatening public health. A multi-stakeholder process implemented since 2005 in six West African cities, including Accra, Ghana, aimed to integrate UPA into sustainable urban development. However, an internal lesson learned was that local partners may not prioritize every project, and capacity-building efforts might not provide expected incentives for commitment.
Contamination & food safetyPolicyHealthPeri-urban agricultureCommunityWater, land and health in urban and peri‐urban food production: the case of Kano, Nigeria
2003Tony Binns, Roy Maconachie, Adamu Idris Tanko · Land Degradation and Development · Nigeria (Kano)
This paper examines health and environmental concerns associated with urban and peri-urban agriculture (UPA) in Kano, Nigeria. Empirical evidence indicates that industrial and domestic toxins are reaching dangerously high levels, leading to significant pollution of soils and water channels. This raises serious questions about the sustainability of UPA and the long-term health implications of toxin exposure.
Contamination & food safetyHealthPeri-urban agriculturePolicyUrban agricultural production: heavy metal contamination of Amaranthus cruentus L. grown on domestic refuse landfill soils in Ibadan, Nigeria
2003Ogunyemi Awodoyin, Taliat Opadeji · Emirates Journal of Food and Agriculture · Nigeria (Ibadan)
A 2003 study in Ibadan, Nigeria, investigated heavy metal contamination of Amaranthus cruentus L. grown on domestic refuse landfill soils. Lead (Pb) and Cadmium (Cd) concentrations in soils from four landfill sites and a control site ranged from 110.5 to 678.5ppm for Pb and 2.01 to 3.20ppm for Cd. Metal accumulation in Amaranthus cruentus L. tissues was proportionate to soil Pb concentrations, while Cd levels in crop tissues exceeded soil levels. Crop growth and yield were significantly reduced due to Pb and Cd contamination, leading to the conclusion that Ibadan landfills are unsafe for Amaranthus cruentus cultivation, with heavy metal concentrations in the vegetable tissues much higher than FAO/WHO dietary allowances.
Contamination & food safetyHealthPeri-urban agriculture