In addition, agricultural workers often distrust water supplied by employers, and do not bring enough of their own water to adequately hydrate during the day.However, the lack of association of volume depletion to AKI was surprising, given the above findings. Volume depletion has been posited as a mechanism for AKI and potentially further damage.Recent research suggests that chronic volume depletion leads to sustained release of vasopressin and increased uric acid levels, which may precipitate long-term damage to the kidneys.Our findings suggest that heat strain, not volume depletion, may be a more concerning risk factor in this population. Surprisingly, we found an inverse dose–response relationship of body weight and AKI, where those classified as overweight had lower odds of developing AKI than those classified as normal weight. Obesity is generally accepted as a risk factor for the development of AKI;however, one study found that increased BMI is associated with decreased mortality from AKI in elderly surgical patients.The inverse relationship of obesity to AKI in our results is puzzling, though potentially explained by the fact that the addition of occupational characteristics attenuated the relationship of BMI to AKI. If AKI is a result of agricultural work,bato bucket it is conceivable that obese participants modified or reduced their workload, thus reducing their risk of AKI.
Limitations of our study include using a convenience sample by approaching employers to recruit participants at their work sites. Farms that were willing to allow a team of researchers to measure hydration and heat strain may be more likely to protect their workers, for example, stopping work earlier in the day under conditions of extreme heat, and adhering to state regulations for high heat protection. Recruitment of agricultural workers in California is difficult, due to their mobile lifestyle and concerns regarding documentation status, and recruiting a convenience, employer-based sample was the only way to gain access to workers during the course of their work day. A second limitation is the calculation of the PSI variable, used to estimate heat strain. Owing to limitations of our equipment, some of the measurements of heart rate and core body temperature were missing, which may have affected our estimates. We were able to account for this by working with a team of exercise physiologists, clinicians and statisticians to provide robust and accurate estimations. Finally, estimates of AKI based on KDIGO guidelines use a 24-hour measure of urine output, which is not feasible in the field setting. Additionally, elevations in serum creatinine in our sample are potentially related to muscle injury , which we were unable to assess in our study. Despite these limitations, we were able to estimate the incidence of AKI over the course of a work shift and test associations between traditional and occupational risk factors. Agricultural workers are a vulnerable population, often undocumented, living in poverty, culturally and linguistically isolated, with reduced worker protections.The development of AKI over the course of a work shift in this population may lead to further kidney damage, including chronic kidney disease, particularly because it is unlikely that workers know they are damaging their kidneys while working in the fields.
Further research is needed to evaluate the long-term consequences of repeated AKI among farm workers. While occupational regulations are in place to protect workers from heat-related illness, we have shown that workers who experience high levels of heat strain and who are paid by the piece are at increased risk. Fortunately, these risk factors are both modifiable, and incident AKI associated with heat strain and piece rate work may be prevented. Urbanized areas are the fastest-growing habitat worldwide. In the United States, over 80% of the population now lives in cities. It is expected that urban populations will continue to increase significantly in the coming decades. Matching urban population growth is an increase in urban food production; urban agriculture has grown 30% in the United States in the last three decades. Growing food in the city has become an increasingly common pathway to affordable, nutrient-rich, and culturally appropriate foods for people who live in high-cost cities. A myriad of issues complicates urban agricultural production. Once urban farmers gain access to land, they must address many abiotic factors unique to cities that disrupt the ecosystem services many agroecological practices rely on. Increased impervious surface and decreased canopy cover affect hydrological and bio-geochemical cycles and increase urban temperatures. Past land uses can affect soil quality and composition. These abiotic factors often exacerbate crop damage from herbivorous insects. Herbivorous pests in urban agriculture can become more persistent and increase in abundance in response to favorable environmental conditions in cities and cause damage to crops. In urban agriculture, management of pests is almost universally accomplished through cultural practices as pesticides are rejected for environmental and health reasons.
Many urban agriculturalists turn to agroecological pest management practices to increase on-farm beneficial insects and regulate pest populations. Agroecological practices proven on rural farms, such as crop diversification and floral resource provisioning, have been implemented to varying degree in the built environment, often with conflicting results. This research focuses on understanding urbanization impacts on agroecological pest management in urban agriculture. Specifically, how on-farm diversification schemes affect biological control services from parasitic Hymenoptera . Recognizing how these biological control services function in fragmented urban landscapes is vital to urban farmers. Understanding agroecological pest management practices and factors that may affect ecosystem function on urban farms necessitates understanding urban farm biophysical composition. Over three years, biophysical data were collected on twenty-nine urban farms in the San Francisco Bay Area. The physical composition of urban farms were measured, including overall size, areas of production, and percentage of land not in agricultural production. Indicators of specific management practices, such as type and percentage of mulch and ground cover, floral diversity, and crop and non-crop biodiversity, were recorded, and overall production was assessed. We found that practices associated with APM are widely adopted and are often practiced concurrently. Our research shows that urban farms are highly productive, and most crops grown feed local community members. Land use and spatial composition of urban farms varied, but the production area as a percentage of the total area is often low,hydroponic grow kit and areas set aside for pollination gardens or beneficial habitat are common. As agroecological pest management in urban agriculture is an understudied topic, a systematic review of research specific to UA and biological control services was conducted. Previous findings recorded significant impacts on both natural enemy and herbivorous pest populations in response to landscape and local effects, but findings remain inconsistent. Local management factors related to agroecological practices, including increased floral abundance, mulch and leaf litter, high plant species richness, and structural diversity, had significant beneficial effects on natural enemy abundance, richness, and biological control services. We conducted a two-year experiment testing the effects of local management practices and landscape effects on parasitic Hymenoptera, aphids, and crop damage on common Brassica crops. Two fundamental hypotheses in conservation biological control: the enemies and the floral nectar provisioning hypotheses, were tested in novel urban agroecosystems. Local and landscape factors were measured and assessed for their influence on PH populations on eleven San Francisco Bay Area urban farms. Farms were selected to represent a variety of sizes and surrounding imperviousness. Our research indicated that Local factors, including increased mulch coverage, crop richness, and percent of non-crop areas, were predictors of increased PH abundance and aphid parasitism rates. To test the effects of floral provisioning on PH we sampled thirteen common floral species across community partner sites to link common floral species in urban farms to PH families and subfamilies known to utilize aphids as hosts. We found that PH had no feeding preference, and floral species had little impact on PH abundance. To assess the second criterion of the nectar provision hypothesis, a demonstrable reduction in pests or crop damage, we looked at aphid abundance, rates of parasitism, and overall crop damage on brassicas.
Our results show that farms with increased floral richness have lower aphid counts per plant. Our findings indicate that on-farm habitat manipulations can increase ecosystem function, supporting the enemies hypothesis in fragmented urban agriculture sites. Growing food in the city is not uncommon, but it has rarely been straightforward or without controversy. Historically, the practice has been implemented, supported, and championed during periods of domestic turbulence and economic stress. Conversely, urban agriculture has often been left with little support when “crises” have subsided, or even actively suppressed . Post-WW2, urban agriculture has been especially prevalent in the context of social movements . As worker wages stagnated in the late 60s and 70s, and access to culturally relevant foods became more difficult for rent-burdened people, urban agriculture became a means to supplement diets, especially in BIPOC communities. When the Black Panther Party started community garden networks to support their Free for Children Breakfast Program in the late 60s, the Hoover administration said that the program was the “most influential activity going for the BPP and, as such, is potentially the greatest threat to efforts by authorities to neutralize the party.” Fifty years later, Billy X Jennings, the official archivist of the BPP said that the Breakfast Program was “one of the biggest and baddest things [the BPP] ever did” . Oakland, California, was the epicenter of urban agriculture in the 60s. Presently, in Oakland and many other San Francisco Bay Area cities, urban farmers continue to farm the city. However, urban farmers continue to face challenges. Despite the inclusion of urban agriculture and sustainable urban food production in many city plans, formal policy and financial support are often lacking . Often, urban agriculture is relegated to degraded vacant lots on the margins of high-value urban land. Even though urban agriculture is very productive, it fails to generate substantial profit at scale, therefore, falls outside the concept of “highest and best use”, creating an economic disincentive for support . A lack of secure tenure affects the implementation of long-term practices and investment in farming operations. Despite these difficulties, urban agriculture seemingly thrives – growing every decade and providing fresh and culturally appropriate foods to a wide range of diverse urban communities . While urban agriculture exists in the margins of urban land use cycles, it also persists in a nexus of social, economic, and ecological factors that co-create and shape this land use. These social-ecological and biophysical factors can often seem insurmountable when creating and maintaining urban agroecosystems. Compacted soils must be remediated, and entire ecosystems created out of vacant lots, old sports fields, and former parking lots. Many innovative cultural technologies and practices are implemented during the creation and maintenance of urban agriculture sites. Every urban farmer must draw on a multitude of cultural technologies and agroecological knowledge to overcome the technical barriers of creating thriving agroecosystems that feed their community .Urban farmers often choose to manage pest outbreaks through cultural and mechanical practices that rely on regulating ecosystem services provided by naturally occurring “enemy” arthropods that predate or parasitize crop pests. During initial stages of the research project outlined in Chapter 1 of this dissertation, urban farmers demonstrated a great interest on the ecological management of crop pests, and questioned whether on-farm management practices, such as floral provisioning and agroecosystem diversification, would be impacted by the conditions in the built environment and, if so, whether on-farm management practices could essentially offset these impacts. Concerns about urbanization effects and pest management are not unfounded. Several conditions exist in urban areas that can impact ecosystem function regarding pest management. Firstly, urbanization fragments the landscape and creates a selection pressure for disturbance tolerant species . Frequently these disturbance tolerant species are herbivorous insects who impact urban cropping systems. Herbivorous insects in urban areas have been documented to be more fecund, larger, and persist for longer . Secondly, natural enemies have been shown to suffer detrimental effects from urbanization, disallowing them to reduce or stabilize urban herbivore populations in urban agroecosystems . Because urban farmers typically employ agroecological management practices for pest control, these effects are especially compelling.