Global demand for beef is projected to increase into the foreseeable future (Smith et al. 2018). Thus, affordable, efficient, humane, and low–environmental impact production systems must evolve to keep pace. Unfortunately, efforts to satisfy growing appetites for nutritious and inexpensive beef necessitate significant reallocation of natural resources and ultimately produce more wastes than can reasonably be accommodated in traditional fertilizer/crop cycles. Generation and release of greenhouse gases, odors, excessive nutrient loading, and depletion of available feedstock and water resources are but a few environmental consequences of increasingly industrialized animal protein production.

However, the focus of this Point of Reference is limited to environmental dissemination and potential impacts of veterinary pharmaceuticals and pesticides used during the end stages of the modern beef production sequence. The proportion of cattle finished on industrial feeding operations or feedyards worldwide continues to grow (Smith et al. 2018). “Finishing” refers to a period of several months in which cattle are fed energy‐dense diets to add muscle and fat prior to slaughter and is common practice throughout the United States, Canada, and Australia, with increasing prevalence in Mexico, China, Paraguay, Brazil, and Argentina. Emergence of commercial feedyard operations is made possible by improved cattle genetics but also use of veterinary pharmaceuticals and pesticides to 1) improve feed conversion efficiency, and 2) curb diseases, pests, and undesirable behaviors and physiological processes. Commercial feedyards could not operate profitably without synthetic anabolic steroids, beta‐adrenergic agonists, pesticides, and antimicrobials.

The animal production agriculture sector is the single greatest consumer of antimicrobials. In the United States, animals account for 80% of all antimicrobial use, 70% of which is nontherapeutic. Not surprisingly, antimicrobials are detectable in manures and soils to which manure has been applied (Kay et al. 2004). Less well characterized, yet potentially more far‐reaching than land application is aerial transport. McEachran et al. (2015) discovered that airborne particulate matter (PM) emissions from beef cattle feedyards contained antimicrobials and antimicrobial resistance gene sequences. In addition to antimicrobials, fugitive feedyard particulate matter has been identified as transport media for synthetic steroids (androgens, estrogens, and progestins; Blackwell et al. 2015). These veterinary drugs are among the most potent endocrine disruptors in use today because they are specifically designed to interact with endocrine receptors in vivo.

A wide array of pesticides has also been quantified in fugitive feedyard particulate matter at concentrations much higher than those of airborne growth promoters. Feedyard agrochemicals have been detected in surface waters, on wildflowers, and on wild pollinators collected in the vicinity of feedyards. Peterson et al. (2020) extrapolated permethrin concentrations in feedyard particulate matter to total particulate matter potentially released from all US feedyards. Considered in the context of honeybee toxicity values, particulate matter emitted each day from feedyards in the United States theoretically contains enough permethrin to kill over a billion honeybees.

To gain perspective on the magnitude of waste and potential agrochemical releases from cattle feedyards, consider that a single adult steer or heifer produces roughly 31.8 kg of waste daily. There are approximately 9 million head of cattle on feedyards in the United States at any given time, which translates to approximately 286 200 000 kg of waste generated each day. Ecological receptors may be directly exposed to agrochemicals during land application or via particulate matter deposition of wastes, though indirect exposure pathways such as plant uptake, surface water runoff, or groundwater contamination pose additional risk to humans, wildlife, and aquatic systems. Feedyard waste‐management strategies, when used appropriately, can mitigate introduction of agrochemicals into the environment; but implementation can be costly.

Because many feedyards, especially those in the United States, are located in arid to semiarid regions, aerial transport of agrochemicals via particulate matter emission is more significant than most realize. McEachran and colleagues (2015) estimated that 234 840 kg of airborne PM₁₀ and 21 000 kg of PM_2.5 arose each day from the 8.24 million cattle housed on feedyards in Texas, Oklahoma, Kansas, Nebraska, and Colorado during March 2014. The total mass of suspended particulates is much greater because a significant proportion consists of particles >10 μm in size. Larger particulates are deposited within relatively short distances from originating sources, but the distances that smaller, lighter particulates travel are unknown. Given the annual transatlantic movement of particulates from the Saharan Desert that settle in the United States, it would appear there is potential for feedyard‐derived agrochemicals piggybacking on airborne particulates to reach distant ecological receptors and systems.

A limited number of laws and regulations addressing odors, dust emissions, and water contamination have arisen in response to complaints from people living in the vicinity of feedyards. However, no regulations address the agrochemical content of feedyard particulate matter emissions. Environmental impact assessment guidance for the Food and Drug Administration's New Animal Drug Application process does not recognize particulate‐driven aerial transport of drugs into the environment. Globally, regulations on the use of agrochemicals in beef production vary considerably, and many countries exclude beef imports from countries which permit use of growth promoters and antimicrobials. Import exclusions are primarily related to concerns about human consumption of veterinary pharmaceuticals, not environmental impacts. As a result, open‐air beef cattle feedyards may collectively represent one of the largest unconstrained and unrecognized sources of pesticide, antimicrobial, and endocrine‐disrupting chemical emissions on earth.

The indirect, variable, and difficult‐to‐trace aerial transport pathway presents significant challenges to those of us who are accustomed to studying and regulating contaminants that are directly deposited in the environment and relatively locally distributed. Nonetheless, aerial transport and subsequent ecotoxicological impacts of chemicals in general, and feedyard‐derived agrochemicals specifically, merit further consideration. The need to produce affordable, readily available, and nutritious beef is steadily increasing; but it should not be met at the expense of environmental and human health. Potential ameliorative approaches may include reduced reliance on veterinary pharmaceuticals that have potential to adversely impact local and distant ecosystems, development of alternative green chemistries, integrated pest‐management strategies, effective waste‐treatment and ‐management strategies, and broader understanding of the impacts of agrochemical dissemination. Given the paucity of information available on this topic to date and the influence of powerful lobbying groups associated with the beef cattle industry, insightful, progressive consideration and management of this environmental issue may not keep pace with the demand for beef.