Environmental justice is a social movement of scholarship, policy, and activism that seeks to ensure a clean and healthy environment for all communities (Bullard 2021; Holifield, Chakraborty, and Walker 2018). Environmental health disparities are amplified by limited access to resources and decision-making processes among poor people, immigrants, and people of color (Perkins and Pulido 2022). California’s CalEnviroScreen and the national EJSCREEN are useful tools for revealing communities most burdened by environmental pollution and vulnerability to associated health effects (Faust et al. 2017; U.S. Environmental Protection Agency 2019). To ensure reproducibility and replicability, both tools rely on public databases such as health registries, census data, emitting facility and toxic release violation reports, cleanup site tracking, and environmental monitoring (Faust et al. 2017; U.S. Environmental Protection Agency 2019). However, these tools tend to lose statistical relevance when considering low-density rural areas. The value of regulatory assessment tools for agricultural communities is diluted by inadequate environmental monitoring infrastructure and extensive environmental transport of industrial agrochemicals. Californian agricultural communities need targeted public health and cumulative exposure assessments to develop effective environmental justice interventions. Our project co-developed solutions that address the specific community needs (Schuller et al. 2019) and countered attempts to just provide local decision-makers with extrapolations from regulatory datasets.

Our community-university partnership in Knights Landing (KL) followed community-based participatory action research (CBPAR) approaches to supplement local knowledge about environmental health. This project operated in close collaboration with the university student-run One Health Center and the Chicana/o Studies Department (Sweeney et al. 2018). Community-based participatory action research (CBPAR) is a research approach that engages community members as equal partners in the research process to address community-identified problems and develop solutions that are relevant to the community (Deeb-Sossa et al. 2022; Manzo et al. 2020). Local resident experts can use targeted health assessments and interventions to improve public health through measures such as educating community members about environmental risk, developing mutual aid systems, and advocating for policy changes by local businesses and regulatory authorities (Edgren et al. 2005; Heaney et al. 2011; Mutiga-Waititu 2021; Quandt et al. 2013; Ramírez et al. 2015; Sansom et al. 2016; Svendsen et al. 2010; Thompson et al. 2003). Local resident experts recruited student-researchers to study environmental health factors that could elevate cancer risks. Local resident experts included cancer survivors, fire fighters, parents, grandparents, local service providers, immigrants, community organizers, and experienced farm workers. Local resident experts volunteered to serve as promotora-researchers for this project with temporary university affiliation and hourly compensation for research design and data collection. A promotora-researcher is a community member who is trained to conduct research. They are often bilingual and have a deep understanding of the community's culture and values. Promotora-researchers can play a key role in CBPAR research by building trust with community members, recruiting participants, and collecting data (Bustillos and Sharkey 2015; Deeb-Sossa et al. 2022; Quandt et al. 2013). In our study, promotora-researchers included four Latinas and two white women. Through patchwork funding, the Knights Landing Environmental Health Project (2016-2023) built community partnerships while conducting qualitative and quantitative research (Deeb-Sossa et al. 2022).

KL is an agricultural community in Yolo County located in northern California with a predominantly Latina/o/x population of approximately 1,000 residents (US Census Bureau 2017). The growing season is year-round in the region which allowed most residents to remain in KL year-round without entering migrant farmwork. Despite the wealth produced by the local agricultural industry (Yolo County Department of Agriculture & Cooperative Extension 2022), nearly a quarter of the population lived below the poverty line (US Census Bureau 2017). The lack of environmental monitoring data and small population size made environmental justice research in KL particularly challenging. Further, state-mandated community health assessments often overlooked the specific needs of vulnerable communities like KL (Becker 2015; Diaz, Ainsworth, and Schmidtlein 2019; Ramírez et al. 2015; Schuller et al. 2019). For example, the eight surveys collected from KL residents for Yolo County’s 2014 Community Health Assessment were marginal compared to the 85% of 812 total respondents who reported a urban or suburban city of residence (Yolo County Community Health Branch 2014).

County public health reports aligned with KL community perceptions about a high cancer risk in their neighborhood but lacked ground-truthed data and tangible pathways to prevent toxic exposures. Yolo County vital records, for example, showed the highest unadjusted frequency of cancer fatalities in the northeastern census tract including KL (Figure 1) (Yolo County Community Health Branch 2015, 2018). Cancer was the leading cause of premature death in Yolo County with lung, colorectal, breast, and pancreatic cancers making up most deaths (Yolo County Community Health Branch 2015, 2018). Unlike the county disparities in mortality, the 5-year estimates of age-adjusted cancer incidence rates per 100,000 population in the California Health Map zones that represent KL were similar to the county and state rates for 2015-2019 (Table 1) (University of California San Francisco n.d.). Health indicators in CalEnviroscreen and the national EJSCREEN tool indicated higher environmentally-influenced disease burden in KL (Table 2).

After preliminary discussions between KL residents, the research team decided to identify which potential environmental risk factors for cancer should be prioritized for community-led interventions to reduce exposures to carcinogens. Additionally, the team considered some barriers to early diagnostics and healthy lifestyle options that are protective against cancer and are known to improve prognosis for those diagnosed with cancer. CBPAR was used to evaluate KL residents’ contact with potential carcinogens, which informed community-led efforts to reduce toxic exposures and increase access to cancer screenings for early detection and prevention. Community-owned and -managed research approaches enabled the development of culturally- and structurally-relevant assessment tools and weight of evidence strategies to assess environmental contributions to cancer risk for rural agricultural residents (Deeb-Sossa et al. 2022). This manuscript describes the community survey process, key results as interpreted by the promotora-researchers, and the actions in the community that were facilitated using this data.

Our first response to the perceived high prevalence of cancer among KL residents was developing a cross-sectional survey documenting household, occupational, and behavioral exposures to potential carcinogens. Following a community-owned and -managed approach (Heaney, Wilson, and Wilson 2007), six promotora-researchers assumed leadership of the research process, focusing on identifying and implementing solutions to community concerns. Undergraduate and graduate student-researchers volunteered, completed graduation requirements, and secured grants and fellowships to support project aims. Promotora-researchers took on the day-to-day management of the research. Weekly team meetings enabled identification of community priorities before developing research instruments. Promotora-researchers also engaged with new and existing stakeholders to ensure representative recruitment and analysis. For example, they periodically updated and integrated feedback from residents, community development organizations, faith-based organizations, and community health centers. As our project unfolded, the composition of promotora-researchers fluctuated slightly. Following data collection, for example, one Latina promotora-researcher left the project for personal reasons while two additional residents joined (Latina and white, respectively). The research was determined by the university Institutional Review Board to be exempt from full review due to minimal risk to participants.

Promotora-researchers distributed survey results through word-of-mouth with an infographic handout (Supplement 6), collected residents’ feedback, and invited community members to directly advise academic-researchers at our annual One Health Festival (September 2017). Residents overwhelmingly confirmed the consistency of survey results with their own lived experiences. Further documentation of environmental health and cancer risk perceptions was completed in 2018 through five focus groups and accompanying photovoice projects led by promotora-researchers. During weekly meetings, promotora-researchers prioritized concerns for further community-led action and research. They decided against using our limited resources to address regional issues like traffic or agricultural sources of pollution on account of the high likelihood of conflict within the community regarding action plans; high barriers to reaching and mobilizing regulators and industry; and the perceived threat to the local economy if structural solutions were proposed. As a result, the action priorities became household environmental carcinogen exposure, addictive substance misuse, access to cancer screening, occupational safety, and housing quality including neighborhood isolation from health services (Table 8). The research team built open communication and trust with community members to sustain a partnership that was responsive to existing and emerging needs (Deeb-Sossa et al. 2022). The project was also carefully designed to minimize and mitigate any negative impacts caused by the research.

Promotora-researchers prioritized pesticides for further investigation based on occupational exposure risks (Cockburn et al. 2011; Deziel et al. 2015; Thompson et al. 2003) and potential for drift into residential areas (Deziel et al. 2015; Harrison 2011). California Rural Legal Assistance Foundation and Western Center for Agricultural Health and Safety provided strategies to interrupt the occupational pesticide take-home pathway (Cockburn et al. 2011; Deziel et al. 2015; Thompson et al. 2003). Residential use of consumer pesticides in our sample was similar to other urban and farmworker households in California (Quirás-Alcal et al. 2011). Promotora-researchers shared strategies to reduce pest and pesticide entry with residents, acknowledging that housing quality and maintenance may be more important than knowledge of pesticide exposure prevention. Student-researchers mapped state-monitored potentially carcinogenic pesticide applications by industrial farms in KL and a neighboring organic region. Seasonal application and active ingredient patterns in these two growing regions were validated by quantifying potentially carcinogenic pesticides in household dust and tap water. Moving forward, we aim to evaluate the feasibility of collaboratively developing agricultural pesticide fate and transport models with farm-operators, applicators, and irrigators. In combination with regulatory monitoring, farm-operator tools and protective residential practices could reduce carcinogenic pesticide exposures.

KL drinking water contamination concerns were amplified after two of three public wells failed during a recent drought (2014-2017). In shallow, unregulated private wells further water quality concerns include septic system leakage and agrochemical percolation. KL also has a history of natural toxic metal leaching (Ayotte, Nolan, and Gronberg 2016). A neighboring town where many KL children attend elementary school received a state grant for bottled drinking water deliveries due to arsenic contamination of their community well. A follow-up sampling study, launched in collaboration with a neighboring organic agricultural community, investigated potential carcinogen contamination in private drinking water and irrigation wells. Promotora-researchers provided precautionary advice about effective drinking water treatment strategies and a public water bottle refill station is now being considered (Ayotte et al. 2016). Many residents of KL rely on bottled water due to uncertainty about water quality. Additionally, the research team stayed involved in KL Community Service District strategies to improve water infrastructure and security.

Promotora-researchers intend to address concerns about cumulative exposures to potentially carcinogenic combustion byproducts in KL (California Air Resources Board 2021; Noth et al. 2020; Stampfer et al. 2020). The COVID-19 pandemic delayed plans to partner with farm-operators and local organizations to reduce diesel exhaust, promote household appliance electrification and ventilation, and partner with the Air Quality Management District to address recreational wood and agricultural burning (California Mobile Source Control Division n.d.; Chen et al. 2007; Ross 2015). In response to smoking disparities (American Lung Association in California 2018; Liu et al. 2016; Stillman et al. 2018), promotora-researchers initiated research interviews with smokers and nonsmokers, which revealed a lack of sustainable mental/emotional health services and smoking cessation treatments. The student-run KL One Health Center was tasked to provide services for residents interested in reducing addictive substance dependence or recreational consumption. Promotora-researchers founded peer support groups for residents interested in reducing consumption of addictive substances and seeded youth-focused programs to provide healthy recreational alternatives. They also responded to the community’s food desert status and shortage of safe exercise spaces by constructing a community garden and piloting a micro-transit program to urgently increase access to neighboring city resources (Deeb-Sossa et al. 2022).

Environmental justice is a social movement that seeks to address the disproportionate exposure of marginalized communities to environmental health hazards. Academic research plays a critical role in the movement by raising awareness of environmental risks, providing evidence to support claims of environmental injustice, and helping to develop effective interventions (Heaney et al. 2007). However, criticisms of institution-led research often spotlight a lack of shared power and a focus on scientific priorities rather than community needs. A community-owned and -managed approach for conducting environmental justice research in marginalized communities is ideal because leadership of community members is emphasized throughout the research process, from the development of research questions to the dissemination of findings (Heaney et al. 2007). As such, community control over the research process ensures that the research focuses on finding successful solutions that benefit the community.

In this study, a cross-section of local experts assumed the role of promotora-researchers to conduct environmental justice research alongside interdisciplinary student-researchers in an agricultural community with a perceived high prevalence of environmental hazards and cancer. Background research revealed that national-, state-, and county-level reporting corroborated residential perceptions but was not actionable with limited community resources. A cross-sectional survey and community review process was agreed upon to document environmental health risks while refining environmental justice priorities within the resources of residents and local levels of government to affect. Despite the absence of local environmental public health data, our community-owned and -managed approach to environmental justice research sparked concentrated follow-up research that aligned with community needs and community-led interventions that were prompt and feasible (Abara et al. 2014; Brody et al. 2009; Deeb-Sossa et al. 2022; Sansom et al. 2016).

The research presented in this paper has several limitations. First, sampling was not randomized although promotora-researchers minimized clustering, so results may not be generalizable to other communities. Second, the data was collected by local experts and relied on participant self-reporting, which may have introduced response and recall bias into our results. Third, the research was conducted over a short period of time, which makes long-term trends difficult to identify such as the health impacts of chronic exposure to air pollution. Fourth, while our study was powered to document community-level patterns, the small sample size limited our ability to run statistical analyses. As a result, qualitative research was designed to subsequently document and address disparities within the KL population. Lastly, the research did not assess the cost effectiveness of the community-led environmental health assessment survey. Overall, this study provides valuable insights into the potential benefits of a community-owned and -managed approach to environmental justice research. However, our community-specific data, with modified questions, may limit both the ability to replicate our survey findings and the comparability of our community action results to other environmental health monitoring and environmental justice interventions.

Our study demonstrates the value of community-owned and -managed research to develop effective environmental public health interventions that reflect community needs. This approach can help identify and address environmental hazards that are disproportionately impacting California's rural agricultural communities. Findings from this study are analytically generalizable (Yin 2018) to other rural communities with similar population sizes, levels of environmental health information availability, and patterns of environmental risk (Cannon 2021). Details of the history of this community-university partnership and the resources that were available to this research team are detailed in Deeb-Sossa, 2022. Likewise, our approach may serve as a model for environmental justice researchers striving to promptly reduce environmental health risks in marginalized communities.

Community ownership and management, in combination with CBPAR, increased the rigor, reach, relevance, and representativeness of our environmental justice study in a small, agricultural community (Balazs and Morello-Frosch 2013; Heaney et al. 2007; Sansom et al. 2016). Local experts helped to overcome community-specific research challenges (Abara et al. 2014; Edgren et al. 2005; Quandt et al. 2013) and they provided critical context as community priorities advanced in response to interventions and current events (Banna et al. 2010; Quandt et al. 2013; Sansom et al. 2016). Likewise, student-researchers provided university resources to sustain research activity in the form of technical assistance and fundraising (Brody et al. 2009; Sansom et al. 2016). Student-researchers embraced CBPAR despite pressures to follow established extractive research routes and many academic sacrifices were made to prevent delays in community action (Deeb-Sossa et al. 2022). The survey process and results steered by local experts led to expanded research directions and implementation of feasible community actions over six years despite shortcomings in our sustained efforts to achieve structural change (Davis and Ramírez-Andreotta 2021).

CBPAR is a powerful tool for advancing environmental justice and improving environmental public health in the absence of local, representative data. Our team cautions that communities without existing institutional partnerships may struggle to replicate the scale and pace of action demonstrated here (survey was completed in 4 months with under $5,000 in pilot funding) (Abara et al. 2014; Balazs and Morello-Frosch 2013; Sansom et al. 2016). Such approaches are necessary to address multifactorial environmental justice concerns like cancer within a specific neighborhood or community context, even if statistical and other research limitations limit the academic utility of the data generated. Communities can initiate a swift, customized, representative environmental health assessment to serve as a starting point when seeking institutional support, funding, or larger research initiatives.