Research & reports

Nazir Muhammad Abdullahi, Ernest Chukwusoro IGWE, Munir Abba Dandago, Naima Umar · FUDMA Journal of Sciences · Global

This review discusses heavy metal contamination in food crops, identifying wastewater irrigation, agrochemical abuse, contaminated fields, atmospheric deposition, and unethical mining as primary sources. Agricultural soil in urban and peri-urban areas is heavily contaminated due to anthropogenic activities, with wastewater irrigation intensifying this contamination. Heavy metals are transferred to food crops during production and subsequently to humans upon consumption, posing a detrimental risk.

Marta Crispo, Miriam C. Dobson, Roscoe S. Blevins, William Meredith, Janice A. Lake, Jill L. Edmondson · Environmental Pollution · United Kingdom

Heavy metal (HM) and metalloid concentrations were assessed in 200 urban horticultural soils across ten UK cities. HM were found to be widespread, with most concentrations below UK soil screening values (C4SLs). However, 83% of lead (Pb) concentrations exceeded C4SLs, which is a significant concern. Bioavailable HM concentrations represented a small fraction (0.01–1.8%) of total concentrations, and black carbon (BC) and organic carbon (OC) were suggested to contribute to HM immobilization.

Seema Purushothaman, Sheetal Patil, Raghvendra S. Vanjari, A. R. Shwetha · · India (Bengaluru)

A participatory assessment in Byramangala, Bengaluru, explored farmers' perspectives on using wastewater (domestic sewage with industrial effluents) for irrigation. The study found that farmers were adapting to a heavily polluted environment, which resulted in restricted crop choices, lower produce prices, health impacts, and socio-cultural consequences. Despite concerns about water quality, farmers prioritized health-imparting agriculture and were keen to continue farming, but their preference for treated wastewater was overshadowed by its potential diversion for urban use.

K. K. Dey, Maria Velez-Climent, P. Soria, Özgur Batuman, Vessela Mavrodieva, Guo Wei, Jun Zhou, Scott Adkins, John D. McVay · New Disease Reports · United States (Florida)

In October 2019, Tomato brown rugose fruit virus (ToBRFV) was detected in six of eight symptomatic tomato plants from a 1.6 ha community garden in Alachua County, Florida. The plants also showed symptoms of Tomato yellow leaf curl virus (TYLCV), with three samples testing positive for TYLCV. This marks the first report of ToBRFV infecting tomatoes in Florida, USA.

Camille Dumat · Aspects in Mining & Mineral Science · Global

This paper discusses the negative environmental and health impacts of mining, such as air and soil pollution, despite its socio-economic benefits. It highlights that urban agriculture, particularly in areas near former mining sites, faces challenges regarding soil quality and the production of unpolluted vegetables due to public concerns about contamination.

Ahmed Khadra · IGI Global eBooks · Global

This chapter examines the health effects of climate change, specifically focusing on the global issue of fecal peril caused by intestinal parasites. It suggests that water shortages, driven by climate change, increase pressure on water resources, leading to greater use of urban wastewater for irrigation in urban agriculture. Unsafe management and inappropriate wastewater use are likely to exacerbate the transmission of infectious diseases, including those caused by intestinal protozoa and helminths.

Iwona Makuch-Pietraś, A. Wójcikowska-Kapusta · Land · Poland

This research investigated the distribution, bioavailability, and total forms of zinc (Zn) in soils from domestic and family allotment gardens across six cities in south-eastern Poland. It found that horticultural treatments had a greater impact on sandy soils, and higher Zn contents were present in humus horizons. High values of concentration and Igeo indices indicated significant Zn pollution in these soils, with bioavailable zinc forms being notably high.

Francis Mwanza, Erick Komba, Dominic Kambarage · International Journal of Microbiology · Tanzania (Dar es Salaam)

This study in Dar es Salaam, Tanzania, investigated the occurrence, antimicrobial resistance, and genetic relatedness of E. coli isolates from 156 samples of manure, vegetables, and fish. Of these, 36 samples (23.1%) were positive for E. coli, yielding 48 isolates. A significant finding was that 25 (52.1%) of these isolates were resistant to at least one antimicrobial agent, and 12 (48.0%) showed multidrug resistance, indicating a potential microbial health risk to humans through contamination.

Adugnaw 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.

Cecilia Herbón, María Teresa Barral, Remigio Paradelo · Applied Sciences · Spain (Santiago de Compostela)

The concentrations of trace elements Cu, Pb, Zn, Ni, Cr, and As were investigated in 55 urban soils in Santiago de Compostela, northwestern Spain. While most soils showed higher trace element concentrations than regional backgrounds, they were not classified as contaminated according to Spanish regulations. However, geoaccumulation index values indicated low to moderate pollution levels in most soils, with Cu, Pb, and Zn highest in city center green areas, and Cr and Ni linked to parent material lithology.

Chammi P. Attanayake, Ganga M. Hettiarachchi, Mónica Palomo, Gary M. Pierzynski, Blanca Calderón · ACS Agricultural Science & Technology · United States

The effect of limestone and composted manure on lead (Pb) in vegetables and Pb bioaccessibility was assessed in a contaminated urban garden (total Pb ~200 mg kg⁻¹). Amendments did not affect Pb in vegetables or Pb bioaccessibility. Peeling reduced Pb concentration in radish by half, and removing surface dust reduced Pb in leafy vegetables by 40-50%. Daily Pb intake from consuming lettuce and carrot/beetroot from this garden was approximately 1.5 times higher than the interim reference level proposed by the U.S. Food and Drug Administration.

Xingjia Wang, Wenbo Li, Dongyan Wang, Songze Wu, Zhuoran Yan, Jiaqi Han · Ecological Indicators · China

A 'trinity' assessment method was developed to evaluate heavy-metal contamination in peri-urban soil–crop systems in Northeast China, covering total, available, and accumulated heavy metals. While traditional methods indicated less contamination, the trinity method revealed spatial clustering of heavy-metal contamination in cultivated lands caused by urbanization and industrialization, and a decreasing urban–rural trend in contaminated areas, particularly in transition zones.

Jonathan Hall, Isabel Shargo, Niya Khanjar, Jianna Howard, Laura Schmidt, Ashley Deng, Camryn Edwards, Isabelle Berman, Joseph Galarraga, Sacoby Wilson · Environmental Justice · United States

This study in Baltimore, Maryland, used GIS mapping and spatial analysis to assess the proximity of urban farms to environmental hazards, including those with heavy metal contamination. Analyses indicated that contamination of urban farms is a possibility due to proximity: more environmental hazards were found in census tracts with urban farms, and low-income communities of color had hazards near urban farms. Historically industrial areas showed a higher concentration of environmental hazards with heavy metal or unknown contamination.

Isabel Shargo, Jonathan Hall, Ashley Deng, Niya Khanjar, Camryn Edwards, Isabelle Berman, Joseph Galarraga, Sacoby Wilson · Landscape Journal · United States (Baltimore)

This study in Baltimore, Maryland, used GIS mapping and hotspot analysis to assess the proximity of urban farms to environmental hazards. Most urban farms were located in low-income communities of color. However, most environmental hazards were not near urban farms but in predominantly White areas or historical industrial centers. Despite a generally low risk of contamination, some urban farms in low-income and Black/African American communities were potentially contaminated by hazardous sites.

Elisabeth Ziss, Wolfgang Friesl‐Hanl, Sophia Götzinger, Christoph Noller, Markus Puschenreiter, Andrea Watzinger, Rebecca Hood‐Nowotny · Sustainability · Europe

In the "Heavy Metal City-Zen" citizen science project, community members in urban gardens in Vienna, Austria collaborated on collecting soil and plant samples to assess heavy metal contamination risk. Trace metal concentrations were generally below guideline thresholds, but at a few garden sites soil concentrations of lead, cadmium and zinc exceeded Austrian recommended limits, and at two sites plant trace metal concentrations exceeded European food standard limits; the project proposes expanding the citizen-led sampling to all of Vienna so new gardens can assess local soil risk before planting.

Anna Barra Caracciolo, Valentina Terenzi · Microorganisms · Global

A review of the rhizosphere as a microhabitat of intense chemical dialogue between plants and microorganisms covers synergistic interactions that can enhance plant function and productivity, including responses to stress conditions such as heavy metal (HM) contamination, alongside the risks such contamination poses. Where heavy metals are present in agricultural soils, there is a risk of metal uptake by edible plants leading to bioaccumulation in humans and animals with detrimental health consequences, and plant productivity itself can be negatively affected; many bacteria have defensive mechanisms for resisting heavy metals and can improve plant responses to HM stress, but achieving such beneficial rhizosphere interactions is described as hard to attain in agroecosystems managed with traditional practices that focus on maximizing crop yield.

Anthony Kamara, Foday Thullah · Journal of Nuclear Technologyin Applied Science (JNTAS) /Journal of Nuclear Technologyin Applied Science (JNTAS) · Africa

A study measured background radiation at the two major dumpsites in Freetown, Sierra Leone — Kingtom and Granville Brooke — which are also used for urban agriculture and where youths scavenge scrap metals and plastics daily. Using a portable Radiagem survey meter and GPS, researchers took 10 in-situ dose-rate measurements at each site. The mean equivalent dose rate was 0.8 mSv/year at Kingtom and 1.1 mSv/year at Granville Brooke; Kingtom slightly exceeded the UNSCEAR permissible limit but stayed below the ICRP limit, while Granville Brooke exceeded both the UNSCEAR and ICRP limits. The study concludes both dumpsites could become unsafe in the near future from cumulative radiation exposure for workers, scavengers and other exposed individuals.

Yvonne Ma, Jessica Chen, Karen Fong, Stephanie Nadya, Kevin J. Allen, Chad Laing, Kim Ziebell, Ed Topp, Laura M. Carroll, Martin Wiedmann, Pascal Delaquis, Siyun Wang · Antibiotics · Canada

Genomic and phenotypic analysis of 55 Shiga toxin-producing E. coli (STEC) isolates of diverse serotypes, recovered from surface waters and sediments in a mixed urban/agricultural landscape in British Columbia, Canada (Antibiotics, 2021), found reduced antibiotic susceptibility across multiple drug classes: florfenicol (65.5%), tetracycline (52.7%), ampicillin (49.1%), streptomycin (34.5%), amoxicillin/clavulanic acid (21.8%), kanamycin (20.0%), ceftiofur (18.2%), trimethoprim-sulfamethoxazole (12.7%), gentamicin (10.9%), chloramphenicol (7.3%), ceftriaxone (3.6%) and cefoxitin (3.6%), while all isolates remained susceptible to ciprofloxacin, nalidixic acid, ertapenem, imipenem and meropenem. Eight isolates (14.6%) were multidrug resistant, and resistance genes including floR, dfrA, sul1/2, tetA/B, aadA, aph, blaTEM-1b and blaCMY-2 were identified alongside multiple plasmid replicon types. The resistance profiles matched those reported in generic E. coli from food animals, and the authors conclude that aquatic environments in the region are a potential reservoir for the maintenance and transmission of antibiotic-resistant STEC, their resistance genes, and associated plasmids.

Olga Romanova, Sarah Taylor Lovell · Urban Agriculture & Regional Food Systems · Global

This review assesses the capacity of woody species (trees and shrubs) used in urban food forests to accumulate polycyclic aromatic hydrocarbons (PAHs), heavy metals (HMs), and metalloids, given limited existing literature on food-safety risk in urban fruit- and nut-producing trees compared with annual crops. General trends identified were (a) lower risk of HM and PAH accumulation in woody species than in vegetables, and (b) less accumulation in the fruit of woody species than in other parts of the same species. However, these trends are not always consistent, and accumulation depends on factors such as the concentration of a given contaminant in the environment, contaminant type, and species or variety. The review states there is a critical need for more research on the safety of growing edible fruits and nuts on trees and shrubs in contaminated urban environments.

Yuliia V. Medvedeva, Анатолій Кучер, Joanna Lipsa, Maria Hełdak · International Journal of Environmental Research and Public Health · Europe

A study assessed the safety of apples sampled across different functional zones of Kharkiv, Ukraine — from industrial areas to school gardens — for consumption. Heavy metal levels exceeded maximum allowable limits in apple samples from all sampling sites, with lead 11.47 to 38.86 times and cadmium 1.76 to 5.68 times the FAO/EU norms; the most contaminated samples came from residential areas, partly due to significant land pollution from various waste types. Hazard index (HI) values varied by age group: 24.37-70.11 for children aged 1-6, 10.28-29.59 for children aged 7-16, and 0.88-2.53 for adults aged 18-65. Non-carcinogenic risks were linked to disorders of the immune, blood, urinary, and nervous systems and to liver and kidney function, and the total carcinogenic risk from eating the apples exceeded the permissible level.

R. Holm Thomas · Lincoln (University of Nebraska) · United States (Lincoln)

This study investigated remediation strategies to reduce heavy metal uptake in soil from a potential community garden lot near a railroad in Lincoln, NE, where elevated concentrations of lead (Pb) and arsenic (As) were detected. In a greenhouse experiment, romaine lettuce was grown. Biochar amendment resulted in the lowest concentrations of Pb and As in lettuce leaves and stems, whereas coffee grounds amendment led to the highest concentrations across all tested plant parts.

Tanmoy Roy Tusher, Md. Eusuf Sarker, Sumaya Nasrin, Tapos Kormoker, Ram Proshad, Md. Saiful Islam, Shamim Al Mamun, A. R. M. Tareq · Toxin Reviews · Bangladesh

This study investigated toxic metal and PAH contamination in rooftop soils and vegetables (red amaranth, spinach) in urban and peri-urban Bangladesh. Urban rooftop soil and vegetables were highly contaminated with toxic metals and PAHs compared to peri-urban samples. Lead (Pb) and cadmium (Cd) concentrations in urban vegetables exceeded safe limits. However, health risk indices indicated that the levels of toxic metals and PAHs in urban rooftop vegetables would not pose carcinogenic or non-carcinogenic health risks for adults and children, deeming them safe for consumption.

Fabien Ilunga Mpanga, Michel Shengo Lutandula⃰ · The Global Environmental Engineers · Democratic Republic of Congo (Lubumbashi)

A study conducted in the Kasungami district of Lubumbashi, Democratic Republic of Congo, investigated the link between the use of polluted waters in urban agriculture and heavy metal contamination in soil and cultivated vegetables (amaranths, broccolis). Physicochemical and mineral analyses of water, soil, and plant samples revealed that heavy metals, except cobalt, were present in the water used for urban agriculture at concentrations below quality standards, but the soil contained heavy metals at phytotoxic concentrations. Only broccolis were contaminated with lead, while amaranths had heavy metals below quality standards. These findings suggest that urban agriculture in large agglomerations of the DRC could endanger consumers' health.

Gábor Teke, Katalin Hubai, Dorina Diósi, Nóra Kováts · Bulletin of Environmental Contamination and Toxicology · Global

This laboratory study assessed the foliar uptake and accumulation of airborne polyaromatic hydrocarbons (PAHs) in lettuce (Lactuca sativa) using an aqueous extract of urban aerosol, following OECD Guideline 227. The study found significant accumulation of PAHs in lettuce, with naphthalene showing the highest bioconcentration factors (BCFs) and anthracene, pyrene, and fluoranthene showing the lowest bioaccumulation potential. The BCF of each PAH strongly correlated with its molecular weight.

Cleusa Fernandes Ramos, Andréia Assunção Soares, Isabela Carvalho dos Santos, F. Ramos, Odair Alberton, Luciana Kazue Otutumi, Lidiane Nunes Barbosa, Ricardo de Melo Germano, Daniela Dib Gonçalves, Luiz Sérgio Merlini · Journal of Pure and Applied Microbiology · Brazil

This 2020 study in Brazil evaluated the bacteriological quality of six medicinal plants from community gardens, including Cymbopogon citratus and Aloysia citriodora. Analysis of cold extracts revealed bacterial contamination, with Plectranthus barbalus showing the highest aerobic mesophile count and Aloysia citriodora the highest coliform count at 45°C. However, the study concluded that heat treatment (boiling for teas) can significantly reduce or eliminate this bacteriological contamination, making the plants safe for consumption.