Research & reports

Joseph 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.

Gideon Aghaindum Ajeagah, Yaka Diane Armelle Moussima · Journal of Ecology and the Natural Environment · Cameroon

A study in an urban stream in Yaoundé, Cameroon, characterized Balantidium coli cysts and evaluated environmental factors influencing their dispersal. Round (825 ± 610 cysts/L) and oval (246 ± 300 cysts/L) cysts were found. High abundances of cysts were observed in stations along a piggery effluent near a major market, with higher densities recorded during the short rainy season. The lowest cyst densities were found upstream and downstream.

Jin‐Won Kim, In‐Wook Choi, Won-Seok Na, Enkhjargar Baljii, Yong-Man Yu, Young Nam Youn, Young‐Ha Lee · Journal of Food Hygiene and Safety · South Korea (Seoul)

From September to October 2012, 530 samples of nine vegetable types were collected from 11 urban community gardens in Seoul to assess their microbiological quality. Mean total aerobic bacteria and coliforms were detected at 6.3 log CFU/g and 4.3 log CFU/g, respectively, with coliforms found in 67% of samples and E. coli in 2.3%. While foodborne pathogens were not detected, the presence of coliforms and E. coli indicates room for improvement in microbiological safety.

Qiang Liu, Jingshuang Liu, Qicun Wang, Yang Wang · Human and Ecological Risk Assessment An International Journal · China (Jilin City)

This study investigated heavy metal pollution levels by collecting 50 soil samples from urban vegetable fields in Jilin City, China. Mean contents of Pb, Cr, Cu, Ni, Zn, and Cd were higher than their corresponding natural background values. However, the distribution of comprehensive pollution index values indicated that concentrations of these heavy metals in most agricultural fields did not exceed baseline values affecting agricultural production safety and human health according to China's soil environmental quality standard, concluding insignificant contamination by these metals in Jilin City.

UM 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).

A. 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.

Abdirahman Osman Warsame, Fadumo Abdi Mohamud, Ahmed Hassan Ali · Zenodo (CERN European Organization for Nuclear Research) · Democratic Republic of the Congo (Kinshasa)

This scoping review synthesized evidence on the association between heavy metal contamination in vegetables sold in Kinshasa's urban markets, Democratic Republic of the Congo, and human biomarkers of consumer exposure. Available evidence consistently showed that vegetables, particularly leafy greens, from Kinshasa markets contained elevated levels of lead and cadmium, often exceeding international safety limits. However, studies directly linking vegetable contamination with human biomarkers are notably scarce, suggesting a potential exposure pathway but not establishing definitive causation.

Ashley S. Harms, DeAnn Presley, Ganga M. Hettiarachchi, Chammi P. Attanayake, Sabine Martin, Steven J. Thien · Natural sciences education · United States (Kansas City)

This case study examines the decision faced by Mr. John Holloway in Harmony Park, Kansas City, MO, regarding establishing a community garden on a vacant brownfield site in 2009. Concerns arose about soil contaminants on the site, leading to a dilemma about the potential harm versus benefits of gardening in a food desert. The case requires students to evaluate environmental, agronomic, human health, social, and economic issues related to urban soil contamination.

Anjar Lulu Sakinah, Enny Zulaika · Jurnal Sains dan Seni ITS · Indonesia

This study aimed to isolate Azotobacter strains from the Eco Urban Farming ITS land in Indonesia that are resistant to HgCl2 and potentially produce mercury reductase enzymes. Ten HgCl2-resistant Azotobacter isolates were obtained, with isolates A5, A6, and A9 showing the highest resistance at 20 mg/L HgCl2. Isolates A5 and A9 were identified as having the potential to produce mercury reductase enzymes.

Suarau Odutola Oshunsanya, Tolafe Olayinka Adeniran · Agricultura tropica et subtropica · Nigeria (Ibadan)

A field experiment in Ibadan investigated the quality of irrigation water used for dry season vegetable cultivation along Ona-stream. Water samples from five isolated ponds and one locally dug well were analyzed for heavy metal status. Results showed high concentrations of Pb, Cr, and Co in soil from five farms (A-E) near the stream, and isolated pond water also contained Cr, Co, and Pb exceeding safe consumption thresholds. All vegetables irrigated with untreated isolated ponds contained Cd, Pb, and Ni concentrations above maximum permissible standards, posing potential risks to human health.

David R. Koenig · BIOS · United States (Sacramento)

This research project, conducted at the University of California, Davis, aims to understand how elevated soil lead levels may affect urban gardening activities in Sacramento, CA. The study investigates the distribution of soil lead levels in the city and how knowledge of this information impacts the local community. Elevated soil lead levels are identified as a potential barrier to urban gardening.

Ande O.T, Adetunji A. M, Akinpelu M. E, Senjobi B.A · Journals & Books Hosting (International Knowledge Sharing Platform) · Nigeria

Ibadan metropolis, Nigeria, home to about 6 million people, has raised growing concern over lowland soils in its periurban area, where much of the industrial waste transported by the River Ona is deposited; these soils are used for dry-season farming and contribute to food security. This study aimed to characterize periurban lowland soils around Ibadan and determine their vulnerability to industrial pollution, using a 50m x 50m grid with surface samples taken at 50m intervals, plus representative profile pits described using the USDA method, and particle-size and chemical analyses (phosphorus, nitrogen, exchangeable cations Ca/Mg/Na/K, manganese, and heavy metals including lead, copper, zinc, chromium, iron, and cadmium). Results showed the floodplain's surface soil was fertile, with high nitrogen (0.35 cmol/kg), phosphorus (51.25 cmol/kg), and potassium (0.61 cmol/kg), and phosphorus levels ranging from very high to toxic, between 28.99 and 87.70 ppm. Average heavy metal concentrations were lead 34.30 mg/kg, zinc 171.20 mg/kg, iron 83.97 mg/kg, copper 19.11 mg/kg, manganese 31.10 mg/kg, chromium 0.69 mg/kg, and cadmium 0.3 mg/kg. Predicted soil-to-plant heavy metal transfer coefficients (Pb 35-343; Cr 0.46-4.6; Zn 171-1712; Cu 19-191; Fe 83-840; Mn 31-281; Cd 0.1-10) indicated crops grown in the area could contain toxic levels of these metals; however, high yields and healthy plant condition observed in the field, together with farmer interviews, suggested that the high phosphorus level (28.99-87 ppm) may have inhibited uptake of some metals such as lead, zinc, and copper.

Kim Jin-Won, Yong-Man Yu, Na Won-Seok, Baljii Enkhjargar, Choi In-Wook, Youn Young-Nam, Young-Ha Lee Young-Ha · Horticultural Science and Technology · South Korea

In Seoul, South Korea, 260 samples of Chinese cabbage and lettuce were collected from four urban community gardens and six roof gardens between September and October 2012 and assessed quantitatively and qualitatively for microbiological and parasitological contamination. Mean total aerobic bacteria counts were 6.1±0.8 log CFU/g (range 5.4±0.6-7.1±0.8) and mean coliform counts were 4.0±0.7 log CFU/g (range 2.3±0.6-6.1±0.9), with coliforms detected in 59.6% of the 260 samples. There was no significant difference in contamination levels between cabbage and lettuce, but produce from community gardens showed higher levels than that from roof gardens (p>0.05). E. coli was isolated from 3.1% of vegetables at a level of 1.5±0.2 log CFU/g. Among foodborne pathogens, Staphylococcus aureus was detected in 1.5% of samples, while Salmonella spp., Listeria monocytogenes and E. coli O157:H7 were not detected in any sample. Unidentified parasite eggs were also found in two cabbage samples (0.8% of the total). The results indicate bacteriological contamination is present in produce grown through urban farming in Seoul, and the study calls for efforts to reduce biological contamination during cultivation.

Rebecca Kessler · Environmental Health Perspectives · Global

As interest in urban agriculture grows, researchers are working to manage the risks of contaminated urban soils. The focus is on maximizing the benefits of urban gardening while minimizing the potential hazards associated with soil contamination.

Sam E. Wortman, Sarah Taylor Lovell · Journal of Environmental Quality · United States

This review paper characterized the limited state of scientific knowledge regarding abiotic environmental factors threatening the growth of urban agriculture in the United States. It identified challenges influencing urban cropping systems, including soil contamination and remediation, atmospheric pollutants and altered climatic conditions, and water management, sources, and safety. The development of a science-based approach in these areas is noted as essential for the economic and environmental sustainability of urban agriculture.

Robert Garey Stewart, Marcel Korth, Laurenz Langer, Shannon Rafferty, N Rebelo Da Silva · · Global

This paper is a protocol for a systematic review on the impacts of urban agriculture programs on food security and nutrition in low and middle-income countries. It notes potential disadvantages of urban agriculture, including contamination, spread of diseases, depletion of water supplies, soil erosion, and health risks from pesticides. The review aims to identify, appraise, and synthesize evidence on these impacts comprehensively and transparently, given that the existing evidence-base is not well understood.

Susana Olivares Reumont, Damarys García Céspedes, Lázaro Lima Cazorla, Israel Saborit Sánchez, Axel Llizo Casals, Pedro Pérez Álvarez · Revista Internacional de Contaminación Ambiental · Cuba (Havana)

This study investigated levels of Cu, Pb, Cd, and Zn in soils and vegetables from 17 urban agriculture farms around the "Calle 100" landfill in Havana, Cuba, during 2006-2007. Findings showed that 35% of soils exceeded typical Cuban agricultural ranges for Zn, and 52% for Pb. Critically, 23% of soils surpassed phytotoxic and international limit levels for Pb, and 12.5% of vegetable samples exceeded Cuban maximum permissible limits for Pb in food for human consumption. The results indicate a need for strict monitoring of horticultural crops in the area due to contamination.

James R. Hollyer · PubMed Central · United States

This article discusses the potential risk of rat lungworm (Angiostrongylus cantonensis) in Hawai‘i's local food supply, which can cause eosinophilic meningitis if ingested by humans. While the statistical risk is extremely low compared to other foodborne agents, two individuals in Hawai‘i developed serious eosinophilic meningitis in late 2008 after consuming insufficiently washed local produce. The article highlights the challenge of informing the public about this rare but potentially serious disease, especially amidst efforts to promote local produce and school gardens.

Shazia Iram, Ayesha Zaman, Zaiba Iqbal, Rabia Shabbir · Polish Journal of Environmental Studies · Global

This study screened soil samples from peri-urban agricultural areas to investigate heavy metal contamination and identify heavy metal-tolerant fungi. Results showed that the majority of isolated fungi were resistant to lead (Pb) and chromium (Cr). Among the strains, Aspergillus niger was the most tolerant to Pb with an MIC of 600 mg/l, and Aspergillus flavus was the most tolerant to Cr with an MIC of 400 mg/l.

Marcelo Ortega Romero, Juan Mingot Marcilla, María Jesús García Martínez, Eduardo de Miguel, Miguel Izquierdo‐Díaz, Amaya Gómez · · Spain (Madrid)

This study evaluated the potential health risk from trace elements in urban garden soils in Madrid, Spain. Thirty-six composite soil samples were collected from the top 20 cm of six urban gardens, and concentrations of cobalt, chromium, copper, nickel, lead, and zinc were determined. The findings indicated that urban soils are significantly enriched in trace elements relative to background levels, suggesting a potential health risk.

Mansur Usman Dawaki, Abubakar U. Dikko, S. S. Noma, Umar Aliyu · Food and Energy Security · Nigeria

This study evaluated pollution risks to food security from urban agriculture in Kano, Nigeria, by sampling soil, water, and lettuce from two wastewater-irrigated sites (Challawa, Jakara) and a control site (Watari). Results showed all sites were contaminated with Cu, and the domestic wastewater site was slightly polluted with Pb and excessively polluted with Cd and Cr. Metal levels in irrigation waters exceeded recommended thresholds, and plants at the domestic wastewater site accumulated metal concentrations (Pb=26.21 mg/kg, Cd=1.03 mg/kg, Cr=28.63 mg/kg, Cu=2.66 mg/kg) that exceeded allowable limits in vegetables, indicating a human ingestion risk.

Mucig Charlotte · · France

A survey on rainwater harvesting in community gardens in France indicates that while this practice has been ongoing for years, it is poorly documented and faces challenges in adapting to new French regulations. The findings highlight public health issues for both garden users and consumers of fruits and vegetables, as well as environmental and operational concerns.

Mekonnen Getahun, Yihenew G. Selassie · Journal of Agricultural Science · Ethiopia

A study investigated the extent of contamination of soil, water, and vegetables from wastewater used for irrigation in urban agriculture in Bahir Dar and Kombolcha, Ethiopia. Soil, water, and vegetable samples were collected and analyzed. While heavy metal concentrations in soil were within permissible levels, wastewater samples showed high nitrate and phosphate levels, and boron concentrations in Borkena River and Lake Tana exceeded permissible limits for irrigation. Wastewater drained to Lake Tana exhibited high turbidity and very high BOD, and lettuce and Swiss chard accumulated higher levels of iron, manganese, and zinc.

Vittori Antisari, Livia; Dipartimento Di Scienze E Tecnologie Agroambientali, University Of Bologna, Bologna, Serena Carbone, Ferronato, Chiara; Dipartimento Di Scienze E Tecnologie Agroambientali, University Of Bologna, Bologna, Simoni, Andrea; Dipartimento Di Scienze E Tecnologie Agroambientali, University Of Bologna, Bologna, Vianello, Gilmo; Dipartimento Di Scienze E Tecnologie Agroambientali, University Of Bologna, Bologna · Archivio istituzionale della ricerca (Alma Mater Studiorum Università di Bologna) · Italy (Bologna)

Concentrations of heavy metals (Ba, Cd, Co, Cr, Cu, Ni, Pb, V, Zn) were determined in topsoil, plants, and moss tissues in the suburban area of Bologna, Italy, due to an urban waste incinerator and other atmospheric emission sources. No correlation was found between metal content and the incinerator plant's distance. The pollution load index (PLI) for soil and moss indicated low environmental pollution, but the highest values in sites downwind of the incinerator and in a craft area indicated moderate pollution.

Kibassa, Kimaro, Shemdoe · Scientific Research and Essays · Tanzania (Dar es Salaam)

A study assessing heavy metal concentrations in soils from selected urban agriculture areas in Dar es Salaam, Tanzania, found that zinc, chromium, cadmium, lead, and copper levels in all six investigated sites were within the Tanzania Bureau of Standards permissible limits. The highest values for copper, zinc, and lead were observed in Tazara Mchichani, potentially indicating pollution from surrounding manufacturing industries. Flooding did not appear to influence the distribution of these heavy metals.