Potential Policy and Community Implications of Equitable Organic Waste, Compost, and Urban Agricultural Systems in the United States

Abstract

Background:

Urban organic waste diverted from landfills for use as compost feedstock may help mitigate and adapt to the effects of our changing climate. Yet, compost produced from urban food and yard waste is often a source of contaminants harmful to human and environmental health. Efforts by multiple municipalities are increasing residential and commercial food and yard waste collection; however, finished, tested compost is typically unavailable to those contributing the waste and whose gardens would benefit.

Objectives:

This commentary evaluates the relative equity and safety of U.S. organic waste cycles in relation to urban and peri-urban agriculture (UA) and waste stewardship. We a) explore historical structures that have led to siloed food and waste systems and b) provide recommendations to promote safer compost production from urban organic waste inputs. The engagement of intersectional partners in the creation of equitable policies and contracts that integrate food and waste justice is crucial to this work.

Methods:

A 15-y relationship between community, academic, and government partners in Boston, Massachusetts, has increased access to health-promoting community gardens. Historical concerns raised by gardeners resulted in improvement to the quality of compost sourced from municipal organic waste and motivated a case study of Boston and three other cities (Seattle, Washington; San Francisco, California; New York, New York). This case study provides the approaches used to source, collect, process, test, and deliver urban organic waste as compost for UA. It informed recommendations to improve the safety and equity of organic waste-to-compost cycles.

Discussion:

Strict feedstock regulation and required compost safety testing are essential to produce safe, city-sourced compost. Balancing the needs of landfill diversion with equitable distribution to all contributors, particularly low-income and food-insecure people, will help concentrate UA benefits within marginalized communities. Adoption of a public health lens may help ensure the safety of nutrient-rich compost available for urban growers through legislation at state and local levels, along with explicit industry contracts. https://doi.org/10.1289/EHP12921

Introduction

Urban agriculture (UA) ranges in form and size from backyard gardens to community gardens (CGs) and small-scale farms. UA has great potential for health benefits through access to green spaces and fresh produce, increased food security, and social connectedness.^1–4 Models predict reduced greenhouse gas (GHG) emissions through UA with decreased food transportation and increased carbon sequestration.^5,6 Although these protective health factors may be especially beneficial for low-income, food-insecure communities, some evidence suggests that UA may contribute to the displacement of low-income individuals while benefiting organizations with greater financial or physical resources.^7,8 In addition, CGs are often created in spaces with heavy previous contamination, including Brownfield sites, Superfund sites, or abandoned lots, with increased likelihood of residual soil contamination by metals and toxic organic chemicals.⁸

Historically, patterns of waste management (collection, treatment, disposal, dumping, or incineration) have disproportionately impacted the health and well-being of low-income communities of color,⁹ but at the same time contributed to increased GHG emissions as organic waste decomposes in landfills.¹⁰ We argue that coordination of urban waste stewardship and food production can build food security while also mitigating and adapting to climate change, though current waste and food systems are often politically, financially, and logistically siloed. We contend that use of compost created from organic waste in UA is of the upmost importance because it reflects waste stewardship through landfill and incinerator diversion^11–13 and decreases bioavailability of some existing soil hazards while increasing water retention and crop yield.¹⁴ Though compost made from recycled waste will never be hazard-free, we provide recommendations to minimize and help prevent continual rises in background hazard levels.

Definitions of organic waste range from very broad—any carbon-based biodegradable material—to more specific, such as paper products, biosolids, and wood. Here, “organic” does not imply “safe,” beneficial, or an achieved certification. We define organic waste as food waste and leaf-yard waste (or green and brown waste). Organic waste can be heterogenous, which means it is a mixture of organics sourced from an establishment, restaurant, or residential source, or homogenous, which means it is one type of waste, such as lettuce waste from a lettuce grower. The U.S. Environmental Protection Agency (U.S. EPA) defines yard waste as materials such as “leaves, grass clippings, brush, and tree prunings.”¹⁵ Through decomposition by microorganisms, organic matter is processed into nutrient-rich compost in the presence of oxygen (aerobic digestion).

Compost created from urban waste inputs presents a different set of concerns in comparison with compost produced in rural or farm settings. For example, urban residential leaf and yard waste may contain lead dust from buildings painted before 1978,¹⁶ and waste from grassy or maintained spaces (i.e., parks) can contain high levels of pesticides or herbicides.¹⁷ Inclusion of municipal solid waste, “compostable” food packaging and tableware, or biosolids (sludge) may introduce other hazards, including per- and polyfluoroalkyl substances (PFAS)¹⁸ and microplastics.¹⁹ The U.S. EPA recognizes food waste and compostable food packaging as sources of PFAS in compost; compost made from food and green waste had higher PFAS concentrations than compost from green waste alone.^20,21 A monitoring study in Boston, Massachusetts, found that City of Boston (CoB) collection of urban residential leaf and yard waste disrupts biogeochemical cycling of carbon (C) and nitrogen (N) in the localized area from where it was taken.²² Therefore, application of compost may be an important source of C and N for urban growing areas where leaf and yard waste are routinely removed, potentially creating nutrient hot spots for targeted growing efforts.²²

Historical land use, density of people and combustion engines, and proximity to industrial operations raise concerns about heavy metals and organic chemicals in UA settings. Through gardening and play, particles containing heavy metals and organic chemicals can be inhaled and ingested.^23–25 Susceptible populations, such as people of child-bearing age and young children, may be at increased risk of adverse health effects from exposure to hazards in soil and soil amendments.^26,27 Weather and the built environment also impact systemic contamination of soil and compost.²⁶ Research has demonstrated both the spread of particles through wind resuspension as a contribution to urban loads of particulate matter with aerodynamic diameter $\le 10\mathrm{\mu }\mathrm{m}$ (${\mathrm{PM}}_{10}$)²⁸ and contamination of groundwater by heavy metals in compost and compost leachate.²⁹

Guidelines for heavy metal content of some soils (including those at Superfund sites and other potentially regulated priority locations) exist at the federal level,³⁰ although none exist for urban soils used to grow consumables. Many states have their own standards or guidelines for metals and synthetic organic chemicals in urban soils.³¹ No federal guidelines exist for compost composition. Several states also lack guidelines related to compost as a soil amendment for growing food. As of 2021, nine states and seven cities had some version of a residential or commercial organic waste ban or requirement for food scrap collection, though bans on organics sent to the landfill do not necessarily imply use as compost feedstock.³² The U.S. Composting Council (USCC) has been working on compost production and use since 1990, and its certification criteria for safe, quality compost are widely accepted (“The Seal of Testing Assurance Program”).³³ The USCC provides recommendations for compost composition and acceptable contaminant levels.³⁴ Though these criteria are not enforceable by any legal entities, they may provide a helpful reference for compost producers and users. Without existing compost standards, guidelines or regulations, community groups and urban growers face the burden of self-identifying hazards of concern.⁸

After community gardeners in Boston, Massachusetts, raised concerns over the quality and content of city-sourced compost, a community partner requested recommendations for how to ensure the safety of compost made from organic waste. Hence, an examination of waste-to-compost cycles in four U.S. cities was conducted to inform the dynamic relationships among urban organic waste collection, compost production, and compost use. Three cities in addition to Boston were selected for review based on current policies and historical efforts to improve UA access: San Francisco (SF), California; Seattle, Washington; New York (NYC), New York. The objectives of this commentary are two-fold: a) to compile the processes of organic waste collection and compost use in urban agriculture by investigating what has led to siloed food and waste systems in the United States, and b) to provide thematic takeaways and recommendations from existing programs on how to integrate organic waste management and urban agriculture by centering safety and equity.

Methods

Collective Case Study

From June-July 2022, a collective case study³⁵ was conducted by reviewing online sources of community activities, city programming, and state legislation related to organic waste diversion and urban compost for UA. In a collective case study, multiple cases are reviewed simultaneously to understand general trends related to the study objective.³⁵ The original motivator of this case study was development of a Best Management Practice (BMP) guidance document requested by a community partner, The Trustees of Reservations (The Trustees). Our BMP is included as a Supplemental File. The search engines Google, Google Scholar, and the National Center for Biotechnological Information’s PubMed were used to capture academic and nonacademic sources that investigated the following topics within each city: a) presence and/or history of urban agriculture; b) use of compost in UA; c) source and composition of compost used; d) compost testing that occurs and whether it is legally mandated; e) organic waste collection and/or bans on landfilling; and f) policies and/or contracts related to the relationship of organic waste collection and compost production. Search terms were designed to meet the study objectives and included municipal compost; urban compost; compost testing; compost regulations; community garden; urban agriculture; UA; UA regulations; municipal solid waste, and MSW. From an initial online search and the historical efforts in the United States around urban agriculture and community gardening,³⁶ SF,³⁷ Seattle,³⁸ and NYC³⁹ were identified as large urban areas with historical and well-financed municipal compost and UA programs. These three cities also have state-level codes that regulate compost composition. Because our community partner was most interested in the safety of compost sourced from municipal organic waste feedstock, it was important that the cities we chose to review in addition to Boston (SF, Seattle, and NYC) were in states with existing legislation on compost contaminants. The findings of our four-city case study were consolidated into thematic takeaways at the community and policy levels, which informed recommendations for an expanding waste-to-compost program in Boston. The original recommendations provided to the CoB have been expanded to a larger conversation on equity in waste and food programming, which may be useful to other municipalities implementing waste-to-compost programs in UA.

Review of the information about these four cities was complemented by informational interviews with managers of The Trustees’ affiliated community gardens and farms, as well as community organizers and urban farm managers in Iowa and Detroit, Michigan. The informational interviews were conducted via phone or video call to learn about compost use, source, testing strategies, and waste stewardship with the objective of informing the BMP for Boston. Three open-ended questions were asked. Question 1: Is compost used in your program, and if so, where does it come from? Question 2: Do you partner with any organizations that participate in waste-to-compost cycles? Question 3: What would be helpful for you to see in this BMP concerning organic waste and the production of safe and accessible compost for urban agriculture? These informational interviews were intentionally open-ended, and the interviewer (academic partner) took a listening role, where notes on the conversation were taken and repeated to the person being interviewed.

Community Partnership

With engaged community partnerships, city-derived compost can be implemented as a resource for UA. By way of example, The Trustees have worked collaboratively with academics at the Boston University School of Public Health (BUSPH) and members of CoB’s Public Works Department (DPW) for more than 15 y. The Trustees are a preservation and land conservation nonprofit, the largest in Massachusetts and the first of its kind internationally.⁴⁰ In addition to owning and managing diverse properties like parks, forests, and buildings, The Trustees oversee more than 50 community gardens in the Boston area. Their work promotes access to green spaces, local food production, and community engagement. About half (49%) of The Trustees’ CGs are in the three Boston neighborhoods with the greatest percentage of Supplemental Nutrition Assistance Program enrollment as of 2016 (Roxbury, Dorchester, Mattapan).⁴¹ The identity of each garden is based on the culture and traditions of its gardeners, which is especially important given the high proportion of foreign-born gardeners who grow food on The Trustees’ properties. Annual events such as The Trustees’ Gardener’s Gathering facilitate communal knowledge and trade sharing. Researchers at the BUSPH have partnered with the Trustees through honest and frequent communication about soil and compost testing and analyses, environmental conditions, garden renovations, and political advocacy.⁴² In 2006, gardeners raised concerns about the quality of the compost, which resulted in analysis of the compost, new initiatives, and contracts to improve the compost quality. These actions were made possible through the trusting partnership developed and maintained between the gardeners, The Trustees and the BUSPH.

The BUSPH and The Trustees have engaged with Boston’s DPW and mayor’s offices through multiple administrations to help ensure that the compost available for the community gardens is as safe for use as reasonably possible.⁴² This mutually beneficial partnership has been built on honesty, trust, and commitments to shared goals. Engagement of The Trustees has helped inform city policy needs, whereas the two previous mayoral administrations and the current administration have annually delivered compost sourced from residential leaf and yard waste to Boston community gardeners. Currently, The Trustees are fielding a growing number of questions from gardeners about soil content in urban gardeners, as well as the composition and safety of compost received annually from the CoB. Thus, the BUSPH–Trustees partnership has together developed recommendations for compost safety and use in urban agriculture.

Discussion

Our case study investigation of organic waste collection and compost use in urban areas highlighted the importance of these interconnected fields with regard to environmental and social justice. We found that multidisciplinary partnerships backed by policy and regulations support organic waste diversion from landfills and incinerators, which reflects waste stewardship.⁴³ Therefore, we recommend that some forms of organic waste should be sourced as feedstock for compost and, depending on the feedstock’s origin and quality, should be available for growers. Especially in a changing climate where droughts are increasing in severity and temperatures are reaching all-time sustained highs, use of compost to retain moisture and provide nutrients is integral to addressing food insecurity through UA.^12,14 To this end, we suggest that municipalities must support an analytically tested waste-to-compost cycle to address carbon emissions, waste justice, and food security. As displayed in Figure 1, we found that partnerships between communities and governing bodies, creation of equitable policies and contracts, and intentional allocation of funds lie at the intersection of climate, waste, and food justice. We recognize that testing will evolve with time as analytical methods improve and we learn more about the characteristics of emerging hazards. When organic materials and compost are given the value they deserve as nutrient-dense resources of regeneration, it is an issue of justice to remove compost inputs without returning finished compost. Urban growers must be equipped with the resources to grow safe, healthy food to address issues of food security.

Figure 1.

Conceptual map showing organic waste nutrient cycling in urban areas. System guiding principles describe themes important to the safe production of compost from organic waste and subsequent use in urban agriculture.

Case Study Summary

The U.S. EPA estimates that 63% of total municipal solid waste produced in the United States in 2018 was organic.⁴⁴ In 2019, organic waste suitable as compost feedstock comprised just over 30% of Massachusetts total waste,⁴⁵ with commercial businesses and residents responsible for 55% and 45%, respectively, of the food waste found in trash.⁴⁶ Restaurants and supermarkets contributed the most food waste of all commercial sources in Massachusetts.⁴⁶ In general, food waste from hospitals and residential centers, including universities, may account for a larger proportion of municipal waste than residents.

Of the four cities reviewed, only SF^47–49 and Seattle⁵⁰ have mandatory bans against landfilling organic waste that apply to both residents and commercial businesses. In 2020, a consultant found that nearly 63% of the State of Washington’s food waste was reclaimed for hunger relief, composted, digested anaerobically, or used for animal feed; 37% was landfilled or incinerated, the majority of which was landfilled (96%).⁵¹ SF composts 80% of the city’s organic waste, whereas the remainder is landfilled or incinerated.⁵² NYC⁵³ and Boston⁵⁴ have different levels of bans related to commercial organic waste and varying “opt-in” choices for residential organics. These differences reflect reliance on industry partners for collection, sorting, composting, and testing (where done), who are often contracted by city offices or departments of public works. Research suggests that state- and federal-level landfill and incineration bans will be important for sustainable management of organic waste.⁵⁵

In addition, state-level regulations differ among the four states surveyed. California,^56–58 Washington,⁵⁹ and New York⁶⁰ have state-level standards for allowable heavy metals, chemicals, and some physical contaminants in finished compost (Table 1).^56–60 There is no required codified state standard for compost feedstock or content in Massachusetts. Municipalities are often required to contract with the lowest bidders, which, in states with no testing or analyte standards, may be less likely to test compost. Therefore, contracts must reflect increased costs for analytical testing necessary to evaluate compost safety, even if not required by state law.

Table 1.

Case study results showing compost production and organic waste cycling in four urban areas.

		San Francisco, California	Seattle, Washington	New York City, New York	Boston, Massachusetts
Regulation of compost production	Regulatory code for compost production	CCR 17868.1 CCR 17868.2 CCR 17868.3 (Established 2018)	WAC 173-450-220 (Established October 2019)	6 CRR-NY 361-3.2 6 CRR-NY 361-3.9 (Established March 2021)	310 Mass Reg 40.0975 (Updated July 2022) These S-1 Soil Standards do not apply to compost. S-1 Standards are reported for comparison to other states’ compost standards.
	Applicable facilities	Compost producers that sell or give away $>\mathrm{1,000}\text{\hspace{0.17em}cubic yd}$ annually.	Compost producers that use solid waste. Anaerobic digesters, composting produced to treat contaminated soil, composting produced from bovine and equine carcasses are exempt and covered by other regulations.	Compost producers that accept between 3,000–10,000 cubic yd of yard trimmings per year.	−
	Sampling strategies and frequency	Composite samples (from 12 individual samples) must be taken for every $\mathrm{5,000}\text{\hspace{0.17em}cubic yd}$ of produced compost, or annually (whichever comes first). A state-certified testing laboratory must analyze the samples.	Annually; Sampling methods described by the U.S. Composting Council (Method 02.01-A through E from 2002 recommendations) may be used.	Annually; Composite samples (from five individual samples) must be collected for analysis.	−
Organic waste cycling	Organic waste bans and legislation	AB 341 enacted in 2011 for businesses; Code 1826 enacted in 2014 for residents SB 1383: Statewide organic waste ban enacted in 2022	Seattle Municipal Code 21.36.082 and 21.36.083: enacted in 2015, updated 2021	Law number 2013/146: enacted in 2013, updated in 2022	310 CMR 19.000: Statewide organic waste ban enacted in 2014, updated in 2022
	Applicable parties	Residents and businesses	Residents and businesses	Select businesses (those producing $\ge \mathrm{2,000}$ tons of food waste per week)	Select businesses only; no regulation of residential waste
	Contracted compost producera	Recology	Cedar Grove Composting	McEnroe Organics; NYC Composting Projecta	Landscape Express; Save That Stuff
	Resources for residents: waste sorting	https://www.recology.com/recology-san-francisco/what-goes-where/#:∼:text=We%20accept%20all%20food%20scraps,placed%20in%20your%20green%20cart	https://www.seattle.gov/utilities/your-services/collection-and-disposal/food-and-yard/food-waste-requirements	https://www1.nyc.gov/assets/dsny/site/services/food-scraps-and-yard-waste-page/brooklyn-composting	https://www.boston.gov/departments/public-works/project-oscar
	Allowable organic waste inputs of potential concernb	Food wrapping; cardboard take-out containers; any products labeled “Compostable”	Food wrapping; cardboard take-out containers	Food-soiled paper products	Compostable plastics; cardboard take-out containers
	Fate of city-sourced finished compost	Recology uses organic waste collected on the west coast (California, Oregon, and Washington) to produce compost for commercial sale. No contracts were found to confirm free Recology-sourced compost for San Francisco residents, though the San Francisco Parks & Recreation Department advertised free compost for residents.	Collected food and yard waste is produced into compost for discounted purchase by Seattle residents.	Community partner organizations produce compost in the city for free/reduced purchase by residents,c though commercial composters produce food-waste based compost for commercial sale outside of city.	Yard and leaf waste have been used to produce compost for free delivery to requesting community gardeners; starting fall 2022, collected food waste will be used by commercial compost producers as feedstock for commercially sold compost.

Note: PFAS, per- and polyfluoroalkyl substances

^a As of summer 2022.

^b Here, we define waste inputs “of potential concern” because of the presence of PFAS inherent to these materials. Beginning in 2023, Washington State banned the addition of PFAS into compostable food packaging.

^c Includes compost-producing partners: Big Reuse, Brooklyn Botanic Garden, Earth Matter NY, LES Ecology Center, The New York Botanical Garden, Queens Botanical Garden, and Snug Harbor Cultural Center & Botanical Garden. It is unclear whether resident organic waste is officially collected by DSNY and processed at these locations, though these organizations do produce compost available for residents.

Our case study found grassroots organizations to be a common factor in implementing regenerative growing practices. In some cities, grassroots activities have been at the nexus of waste-to-resource cycles, often preceding government intervention, including P-Patch in Seattle^38,61 and the NYC Compost Project in NYC (Table 1).⁶² Engagement of community organizations, academic institutions, and legislative bodies is important to allocate resources, advocate for protective policies, and empower communities.⁶³ Addressing waste and its potential contamination with interdisciplinary partners is also integral to promoting safe and sustainable UA, though it is important to acknowledge that waste will never be pristine. In practice, government intervention and regulation may be barriers for urban growers. In addition, we acknowledge that funding for CG management and supplies (including compost production and distribution) is a necessary element to sustainable programming (Figure 1).

The major limitations of this commentary are largely due to the scope and magnitude of the sources. This case study is limited in scope because most of our sources represent electronically publicized growers and growing methods, a narrow sliver in the ancient schema of food growers. In an effort to address the limitations of dependence on electronic sources, direct contact was made with community, city, state, and federal bodies that have an interest or stake in this work. CG and farm managers were consulted, though individual gardeners were not incorporated in this case study, which is a limitation. Although this commentary focused on government engagement in urban and community agriculture in the 21st century United States, the history and progress of composting and food production outside government engagement is invaluable. Below, we explore how our systems developed as they did and provide thematic takeaways and recommendations for pursuing safe, equitable, and complimentary food and waste programs.

Objective One: Historical Structures Have Separated Food and Waste Systems

Across the globe, indigenous individuals and communities have been land stewards and food growers for centuries, often in the face of land dispossession and oppression.^2,64 During the 1600s, European settler-colonizers invaded land occupied and cared for by Indigenous peoples on the North American continent. Indigenous food systems were harshly disrupted through land dispossession, forced dependencies, and assimilation.⁶⁵ Around the same time, 1619 marked the first recorded sale of enslaved individuals in British North America, where the transatlantic slave trade would continue to deliver stolen people from Africa throughout the Americas.⁶⁶ From 1619 to 1860, it is estimated that $\sim 10\text{\hspace{0.17em}million}$ slaves worked $\sim 410\text{\hspace{0.17em}billion}$ hours in the United States.⁶⁶ Agricultural disenfranchisement continued after the Civil War through sharecropping, economic exploitation, and forced removal and killings of Black individuals during the Jim Crow era and beyond.⁶⁷

These trends of exploitation for market economy growth have continued in the modern food systems. American Indian and Alaskan Natives (AI/AN),⁶⁸ non-Hispanic Black, and Hispanic⁶⁹ populations experience disproportionate levels of food insecurity and have higher poverty rates in comparison with White populations. From a national survey analysis, AI/AN individuals living in urban areas were found to have higher rates of food insecurity than AI/AN individuals living in rural or reservation settings, a trend not observed in any other racial/ethnic group.⁶⁸ The remnants of slavery and historically marginalizing practices like redlining and criminalization of immigration have formed the building blocks of a broken food system, clearly seen through land dispossession, labor exploitation, and food inequality.^70–73 Underprotected (im)migrant workers make up $\sim 75\%$ of U.S. farmworkers, most of whom are from Mexico and Central America.⁷⁴ Farmworkers report high rates of injury,⁷⁵ high rates of food insecurity,⁷⁶ and burdens of psychosocial stress and discrimination.^74,77 Today, historically marginalized populations are using UA practices to reclaim agricultural agency and build food sovereignty, elements of which are explored in excellent case studies of Baltimore, Maryland, by Colson-Fearon and Versey⁶³ and of Philadelphia, Pennsylvania, by Gripper.⁷⁸ Challenges such as land access, food distribution, and cost likely impact some urban growers more than others.^78,79

Although marginalized populations have historically been burdened with hazards in our waste systems,⁹ we posit that methods of waste stewardship like urban composting can benefit and uplift UA movements. Environmental justice (EJ) efforts have often faced waste-related emergencies.⁸⁰ The U.S. EPA defines EJ as “the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation and enforcement of environmental laws, regulations and policies.”⁸¹ It is well documented that a disproportionate number of waste facilities, including landfills, incinerators, manufacturers, and hazardous waste sites, are located in residential areas with high proportions of low-income people and/or people of color.^9,82 Composting provides an efficient opportunity for taking accountability of waste and promoting use of an emission-reducing resource.^13,83 Therefore, we argue that justice-oriented policy planning efforts must incorporate proper waste disposal.

Objective Two: Thematic Trends and Associated Recommendations to Promote Equitable Access to Safe Compost

From the case study analysis and through decades of personal experience at the forefront of community garden organizations, we present three themes central to the promotion of safe organic waste cycles, compost production, and compost use in U.S. municipalities.

First, grassroots efforts led by community organizers and members have driven local food production in urban spaces.⁶³ Records show successful grassroot urban composting and gardening in the 1990s (NYC)⁶² and 1970s (Seattle).⁸⁴ Several present-day, city-funded or managed gardens began through community efforts and organizing (like the NYC Compost Program and Seattle’s P-Patch program), though we acknowledge that the electronically publicized efforts are a small sampling of UA efforts that have existed and continue in the United States. In addition to the four cities included in this case study, there are innumerable communities along the urban to rural gradient producing compost and using it to grow food in creative and important ways.^85–87 Urban food production does not need to be formalized or tied to municipal works to increase access to healthy food and foster community empowerment,⁷⁸ though responsibility for the safety of city-sourced growing materials should not burden growers and consumers.⁸

Second, when relationships are approached with mutual respect and goals are communicated clearly, formalized partnerships that include UA organizers, industrial compost producers, and city offices may be beneficial. In the authors’ experience, it has been important to involve groups along the continuum of waste production to compost use (including, but not limited to, residents and businesses, waste collectors, compost producers, sample collectors, certified laboratory analysts, compost users, regulators, and organizers) for successful city-wide waste stewardship systems. Engagement, accessibility, and practicality of residents’ waste production and sorting habits are necessary to achieve legally mandated actions (i.e., organic waste bans). Collaboration between community groups and city officials is needed to negotiate contracts that regulate compost content and accessibility, which are important for the successful use of city-sourced compost.

Third, we found that financial contracts based on state legislation require explicit language around source material, sample collection, and analysis to help ensure safety and accessibility of compost by establishing allowable levels of compost contaminants.^58,88 Contracts between municipal departments and industrial compost producers are important to ensure that compost is as safe as possible. Testing, along with communication and translation of complete test results, gives agency to community organizations and local growers about whether produced compost can be accepted with certainty of content. Training by knowledgeable practitioners, academics, or licensed site professionals is necessary for community organizations and/or growers to advocate for tested compost and to interpret analytical test results. In turn, this practice incentivizes compost producers and waste collectors to ensure safety of feedstock before formal compost production begins.

Compost testing is required in contracts between Seattle Public Utilities and the companies Lenz Composting⁸⁸ and Cedar Grove.⁸⁹ In California, composite samples of compost must be analyzed by a state-certified laboratory before compost is moved off site or used beneficially; frequency of testing is mandated by the state, and percentage of physical contaminants, metal concentrations, and pathogen concentrations in finished compost must meet state standards (Table 1).^56–58 Contracts provide the specifics—they are traceable, binding, and must comply with state standards. Contracts are tools also used to ensure residents’ accessibility to finished compost. Though contracts may present an up-front cost for the city and the compost producer, compost accessibility is important for UA.

Recommendations

We make the following recommendations based on study results, thematic analysis, and the authors’ field experience. Table 2 displays how thematic takeaways from our case study have informed our recommendations, which are grouped into two categories: a) community engagement, programming, and partnerships; and b) policy and legislation.

Table 2.

Thematic takeaways and associated recommendations to promote safety and equity in organic waste cycling for compost use in urban agriculture.

	Themes	Recommendations
Community	Grassroot efforts	Use multilingual and multi-media communication to engage all community members Advocate for specific areas of support based on knowing and working with gardeners and local cultural organizations
	Interdisciplinary partnerships	Establish shared goals Provide reliable and timely communication between groups to build trust among partners
Policy	State-level legislation	Institute organic waste bans, which have been shown to divert organic waste from landfills and incinerators, thus decreasing greenhouse gas emissions Establish codes detailing mandatory testing schemes and allowable contaminant levels of compost to help protect compost safety
	Municipal contracts	Specify allowable compost feedstock, which should exclude materials of concern likes those containing PFAS, metals, or organic chemicals Mandate testing of compost and specify allowable contaminant levelsa Guarantee availability and accessibility of finished compost to community gardeners that want it

^a We provide recommended contaminant levels in our Best Management Practice document (Supplemental File).

Community engagement, programming, and partnership.

Tailored communication and education.

Appropriate communication considers the specific individuals that are using communal growing spaces and city-sourced compost. Especially in urban areas with large immigrant populations, multilingual communication may be necessary and important to include all individuals and all voices. Nonwritten, multimedia communication routes, such as messaging through local radio channels or health centers, can also be used to broaden the scope of garden advertisements and announcements. Similarly, education on the importance of growing food locally, how to secure and establish a growing space in an urban CG, and how to grow and harvest desired foods in urban settings equips individuals and families to access healthy and culturally relevant food to supplement food budgets. Educational and communal conversations around food sovereignty may also help build structures of empowerment.

Advocating for intra-neighborhood specific issues.

Volunteer garden coordinators and neighborhood community organizers may be well suited to advocate for gardener needs that are unique to a specific neighborhood. Residential racial and economic segregation is increasing across U.S. metropolitan areas, with the Boston–Cambridge–Quincy region (Massachusetts) in the top 10 metros with the greatest increase in racial segregation from 1990 to 2010.⁹⁰ Racial segregation and community characteristics vary within cities,⁹⁰ and averaging or generalizing measurements of neighborhood-level need may effectively ignore the unique characteristics of an area. This insider knowledge of specific gardener populations may not be represented in aggregated neighborhood measurements used by local governments but could impact city-wide allocation of funds and resources.

Policy and legislation.

Adoption of organic waste bans and proper pick-up for separated wastes.

Legislation banning organic waste disposal to landfills and incinerators is in place for commercial businesses and organizations in all four cities studied (SF,⁴⁸ Seattle,⁵⁰ NYC,⁵³ Boston⁵⁴) and residential organics bans are active in SF⁵² and Seattle.⁵⁰ These bans reflect coordinated efforts between residents and businesses, city officials, and contractors.

Contracts that regulate compost feedstock and testing of finished compost.

Compost feedstock should be well defined and traceable. States should strongly consider regulating compost inputs and testing requirements, including mandatory minimum frequency of testing, how samples should be collected, and components to test for. Although most compost regulations and permitting processes assessed in this study specify acceptable organic wastes for collection and thus compost input, all four cities allow compostable plastics and food wares in their residential food waste pickups (Table 1). These inputs should be evaluated as a source of chemicals (including PFAS), which will impact testing and application of regulatory standards. Well-defined inputs help ensure safe outputs.

There is no better way to understand the potential hazard or nutrient content of compost than through analytical testing. Though samples can be tested for numerous components, safety testing generally assesses a metals panel, physical hazards, pH, and organic chemicals. Analytical organics panels could also include pesticides, herbicides, and polycyclic aromatic hydrocarbons (PAHs). In 2000–2001, the presence of the herbicide clopyralid in yard waste compost was found responsible for killing or damaging nursery and food crop plants in Washington; the State of Oregon issued a warning that the same herbicide in compost had damaged plants in 2020.⁹¹ Quality testing—for micronutrients, some trace minerals, and biological health—is an important addition to safety testing.

The presence of PFAS in compost is of rising concern across the country.²¹ PFAS contamination of biosolids is well documented as a soil amendment often applied to agricultural fields.^92–94 As methods become available to adequately screen for the presence of PFAS, especially in compost from food waste, it will be important to do so. In the meantime, it is critical to exclude known sources of PFAS from feedstock. Beginning in 2023, the State of Washington has banned the addition of PFAS into food packaging made from plant-based material, exemplifying the power of legislation to protect compost feedstock.⁹⁵ Greater understanding of background PFAS levels and associated human health risks is needed to inform standard development.

Equitable availability and access to finished compost.

Urban agriculture should be tailored to local communities. Especially for food-insecure neighborhoods, CGs and urban farms may provide strong benefits. Use of compost is well accepted as a regenerative growing process. Availability of and access to compost must be ensured for communities with low food security and high climate risk. Removal of organic waste without a contractual obligation to return the tested, finished product to residents who want the compost threatens the equity of growing and minimizes the potential benefits of urban agriculture.

Guaranteeing the safety and accessibility of compost created from urban organic waste is a direct translation of waste stewardship and regenerative agriculture, both justice-centered themes impacted by industry contracts and state-level legislation. Communities contributing organic waste to city-level compost production must be guaranteed recipients of tested, finished compost, if desired. This work is an important step toward regenerative and sustainable UA.