4 Chapter 4: The Impact of Soil Contamination in Urban Gardens on Nutritional Quality of Food and the Communities that Use Them
By Suzette Alancheril
Introduction
Urban gardens, defined as small-scale food production sites within urban areas (CoDyre et al., 2015), have emerged as vital community spaces with the purpose of enhancing local food access, particularly in areas struggling with food insecurity. Urban gardens are connected to the concept of food justice, which asserts the fundamental right of individuals to grow and consume healthy and affordable foods regardless of economic status (Broad, 2016). However, the potential benefits of urban agriculture are threatened by the accumulation of contaminants present in urban soils due to historical and ongoing industrial activities. It is critical to understand what types of pollutants are contaminating urban soils, how they impact the nutritional quality of crops and the communities reliant on these gardens, and how to remediate and mitigate soil contamination. Ensuring the safety and health of urban garden soils is fundamental for achieving food justice, but requires nuanced understandings of biology, urban land use, environmental justice, racial discrimination, and public health.
Section 1. Types of Soil Contaminants
Urban gardens are subject to an array of complex contaminants, a consequence of historical and ongoing industrial activity within city environments. Soil pollutants include herbicides, fertilisers, leachate from landfills, and heavy metals coming from smelters—a furnace used to separate metals from ores and melt raw materials— scrap yards, shipping yards, and paint factories (Hazelton & Murphy, 2021, p. 95-99), causing lead, chromium, cadmium, mercury, and more to pollute the soil. This illustrates how urban soils are a potential sink and accretion site for a range of pollutants. The accumulation of past industrial practices has a long-lasting footprint that can remain in the soil decades later. Centuries of anthropogenic/human activity have modified the cycling of transfer elements in and out of the ecosystem (Gruszka et al., 2024). This becomes problematic and poses health risks when people work with and consume produce grown in contaminated soil. Industrial pollutants such as Polychlorinated Biphenyls (PCBs), now banned in the United States, but historically used in electrical equipment, do not break down easily and remain in the environment for long periods, cycling through water, soil, and air (Hazelton & Murphy, 2021, p. 99). PCBs are also commonly detected in meat and dairy products, contributing to human exposure to this compound (Lee et al., 2022). Petroleum products also point to byproducts from vehicle exhausts and various urban industries on soil quality (Hazelton & Murphy, 2021, p. 99).
Additionally, the Environmental Protection Agency (EPA) does not have a definitive soil standard for growing food in contaminated areas, nor connect soil health and food safety, and lacks regulations over testing soil within urban spaces for safety (Malone et al., 2023).
Geographical location and proximity to highway pollution further exacerbate these risks of soil contamination due to exhaust drift. Land-use patterns, the different ways humans utilize land within cities, are a pathway towards food and soil contamination, highlighting how historical zoning and infrastructure development create environmental vulnerabilities in specific urban areas. Red-lined districts, a racially discriminatory practice used to restrict where marginalized communities could buy or rent housing (Nardone et al., 2020), have urban gardens to compensate for limited access to healthy grocery stores. Redlined districts often have a highway running through them, lack green spaces, and are close to landfill sites. This implies that not all urban gardens are equally safe, and those located in historically industrialized or high-traffic zones may pose a greater risk to the individuals who cultivate and consume their produce. This necessitates a nuanced understanding of urban land-use history and its impact on present-day soil quality.
Section 2. Impact on Nutritional Quality of Crops and Human Health
As contaminants permeate the soil, crop health and productivity are negatively affected (Rashid et al., 2023). For example, when heavy metals, such as lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), and chromium (Cr), infiltrate soil, plants absorb these contaminants and are ingested by humans. Exposure of the human body to high concentrations of heavy metals and other contaminants can lead to the “development of cancer, neural damage, kidney damage, and bone fragility” (Malone, 2022). High levels of heavy metals within soil can negatively affect plant growth and may impair nutrient uptake and utilization. Although urban gardens are intended to increase access to caloric needs, the decline in essential nutrients may pose a threat to nutritional security in food swamps reliant on urban gardens for fresh produce.
Cd, for example, causes browning, decomposition, gelatinous and viscous roots, stunted plane shoots, reduced coloration of leaves of the plant, and rolling leaves (Riaz et al., 2021). Damage to plants as a result of Cd presence in soil can hinder a plant’s ability to absorb and utilize essential nutrients within the soil. Additionally, a healthy root system is integral for water and nutrient uptake. If Cd damages the roots, the plant will not have the capacity to absorb necessary nutrients and grow nutritionally adequate crops. Cd toxicity also affects photosynthesis, a fundamental process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen (Riaz et al., 2021). Photosynthesis also aids in the production of nutrients, minerals, and vitamins. The overall degradation of the plant consequently lowers the nutritional quality of the plant. Therefore, consuming these crops may lead to inadequate utilization of vitamins and minerals, potentially causing malnutrition and other health issues over time. This especially impacts communities within food deserts and food swamps where dietary diversity is limited. Low-income communities reliant on urban gardens in contaminated areas exemplify an environmental justice issue, where communities are not only exposed to higher levels of pollution, but may also have reduced nutrient access through their food sources.
The presence of contaminants in urban gardens creates a double burden: direct exposure to harmful substances and erosion of the nutritional makeup of locally grown food. This compromises the intended purpose of the gardens to serve vulnerable populations and creates a barrier to equitable access to safe and nutritious food.
Section 3. Socio-Economic Impacts on Low-Income Communities
While not exclusive to low-income communities, urban community gardens are often found in redlined or low-income areas to address challenges regarding food insecurity and access to fresh produce (How Urban Gardens Create Greener, Healthier Cities | The Wilderness Society, n.d.). Redlining was a discriminatory and racialized zoning practice implemented in the United States, primarily in the 1930s, that systemically denied fair access to home loans and other financial services to Black residents and residents of color (Lee et al., 2022). Contemporary research reveals that the health of residents in historically redlined areas is significantly compromised, indicating an increased risk of various adverse health outcomes. Although the Fair Housing Act of 1968 outlawed redlining, the redlined neighborhoods are still home to low-to-moderate income and communities of color (Nardone et al., 2020). Additional discriminatory policies, namely the Federal Housing Act of 1949, led to the destruction of Black neighborhoods, and transportation policies, such as the Federal Aid Highway Act of 1965, authorized the demolition of urban areas labeled as “unhealthy slums” to make way for interstate highways (Nardone et al., 2020). Extensive research now shows how redlining and housing policies have led to ongoing racial residential segregation and the continuation of poverty, inadequate access to healthy food, declined quality of green spaces, high levels of pollution, and other factors that influence health (Nardone et al., 2020).
Due to systemic policies rooted in racism, redlined and low-income districts are often subjected to high concentrations of pollution and environmental injustices (Bisgaeir & Pollan, 2018), resulting in contaminated soil that undermines the health of the food intended to combat food insecurity within their urban gardens. This paradox highlights a fundamental contradiction to the intended purpose of urban gardens and their goal to provide access to fresh food in food deserts.
To further illustrate the influence of soil contamination in urban gardens and its implications for vulnerable communities, this chapter will draw upon the findings of a recent study conducted in the Seattle Metropolitan region (Malone et al., 2023). This study gathered data from communities of color due to the higher percentages of people of color who are disproportionately exposed to contamination, and locations with land use histories that may put community members at risk. These locations are also close to major roads and former industrial activity. The study linked the issue of contamination to systemic racism, racist policies, and poor health regulations. This directly connects to the historical context of redlining and environmental racism, leading to pollution in low-income areas. The researchers also interviewed gardeners of the land sites they investigated and found that they were often unaware of the potential harms and poor regulation of contaminants. This lack of information and oversight disproportionately affects low-income communities with less access to resources to test and remediate soils. There are limited choices for gardeners seeking access to healthy food, and the food itself is harmful to their health.
Soil contamination in urban gardens is an environmental justice issue with significant socio-economic consequences for low-income communities. These communities are often reliant on these spaces to combat food insecurity, but are disproportionately burdened by historical policies. Urban gardens are intended to address food justice inequalities, yet they are undermined by disproportionate contamination.
Section 4. Remediation and Mitigation Strategies
Due to the presence of pollutants in urban community gardens, developing remediation and mitigation strategies to promote and maintain healthy environments is integral.
One technique is regular soil testing. This is a foundational first step for any remediation or mitigation effort and is necessary to determine what contaminants are present and the extent of contamination (Amrita Mukherjee, 2024). Testing the soil also provides necessary data for subsequent remediation actions. Additionally, gardeners should test compost for contaminants to ensure they are not importing pollutants into their gardens.
A possible method of soil remediation is phytoremediation, involving the use of plants to get rid of toxins within the soil (Amrita Mukherjee, 2024). This method could potentially be a sustainable and cost-effective strategy. However, another study on phytoremediation determined that this method can often take several months or years to remove the contaminants, and uptake of contaminants is dependent on “bioavailability of contaminants to plants” (Malone, 2022). The study found phytoremediation, although effective, was not a good option for Pb because plants generally do not uptake Pb.
Another potential for soil remediation is bioremediation, involving the use of microorganisms to break down contaminants into less hazardous forms (Amrita Mukherjee, 2024). This can come in the form of bacteria and fungi to break down petroleum hydrocarbons in contaminated soils.
Simpler options include building raised beds filled with clean soil over contaminated soil (Kessler, 2013). Exposed polluted soil can be covered with mulch or grass. However, raised beds can also pick up contamination from urban activity, such as exhaust drift and high-lead soil blown from surrounding gardens (Kessler, 2013).
An integral component of remediation is expert guidance and community involvement (Malone, 2022). Involving communities is essential for creating practical solutions where gardeners can offer valuable insight into what solutions are practical, affordable, and culturally appropriate. Gardeners have firsthand experience with their land sites and knowledge of their land history. Open communication from experts and researchers to community members also builds trust and addresses knowledge gaps in understanding complex scientific information about contaminants and remediation strategies. When gardeners can vocalise their concerns, remediation efforts are more likely to align with their values and perspectives. As discussed in section 3, soil contamination in urban gardens often disproportionately affects marginalized communities and is a product of environmental injustice. Involving residents in the remediation and mitigation planning process empowers them to take control over their environment, health, and well-being, challenging the power imbalances that resulted in the contamination in the first place. Involving both expert guidance and community gardeners ensures that remediation strategies are not only technically sound but also socially just, fostering more effective and equitable outcomes.
Section 5. Interdisciplinary Connections
The widespread contamination of soil in urban community gardens requires an interdisciplinary approach. Urban gardens aid the food justice movement by aiming to increase access to nutritious food in low-income food deserts. The polluted nature of soil within urban gardens and their potential pathways into plants poses risks to plant and human health, creating an environmental and public health issue. The impact of heavy metals on plant growth and nutrient uptake has implications for plant physiology and human nutrition. The historical context behind industrial activity, past discriminatory policies, including redlining, and the long-lasting impact of persistent pollutants, similar to PCBs, is crucial to understanding current contamination patterns and how they disproportionately affect marginalized populations. Ultimately, addressing the complexity of soil contamination in urban community gardens and its effect on food justice necessitates an integrated interdisciplinary approach. Through the combined insights of environmental science, policy, anthropology, history, and food systems, effective mitigation strategies can be developed in order to promote equitable access to food and foster just and sustainable communities through urban agriculture.
Conclusion
The prevalence of soil contamination in urban gardens, particularly within historically marginalized and low-income communities, illustrates negligence in achieving food justice. While these gardens represent a great effort to combat food insecurity and increase access to fresh produce in food swamps and deserts, their potential is severely undermined by the environmental burdens these communities disproportionately bear. Failing to address this paradoxical issue not only perpetuates health disparities but also undermines the very foundation of food justice – the right of all people to access healthy and safe food. Strides to remediate contaminated soil should continue to be taken to better address systemic injustices that compromise access to safe and nutritious food.
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