W1045: AGROCHEMICAL IMPACTS ON HUMAN AND ENVIRONMENTAL HEALTH: MECHANISMS AND MITIGATION
Statement of Issues and Justification
Statement of the Problem.The growing demand for food and fiber will place greater strain on agricultural production and environmental stewardship. Agrochemicals will remain fundamental as integrated pest management tools to assure an abundant food supply. Inevitably, a significant portion of applied agrochemicals may be lost to the surrounding environment, where they can adversely affect human and environmental health. The use of conventional and emerging crop protection chemistries in agricultural and urban pest management will require research on the fate and effects of agrochemicals, along with mitigation strategies, to minimize risks to humans and the environment. Replacement of the W-45 multistate research project will enable multistate collaborations to more effectively advance and transfer science to agricultural and regulatory stakeholders, who require solutions to complex human and environmental health concerns that are beyond the scope of any individual State Agricultural Experiment Station or ARS.
Justification.
Over the next quarter century, the world's population is expected to increase by an unprecedented 90 million people per year. The growing demand for food and fiber will place a greater pressure on agricultural production and growers needs for affordable and efficacious pest management. The need to increase production while reducing associated pressures of agrochemical use on natural ecosystems and human health will pose a difficult challenge for scientists in all areas of basic and applied agricultural research. Although it will be important to provide growers with a variety of biologically-based, sustainable production alternatives, the use of agrochemicals will remain essential in pest management. Exotic weeds and weeds with herbicide resistance or environmental tolerance can invade open habitats very rapidly. Understanding the effects of agrochemicals on target and non-target species will improve our ability to predict and integrate current and potential pest management strategies, providing environmentally sound and cost effective approaches to pest management. These approaches will lead to reduced application of pesticides.
Agrochemical use currently exceeds 500 million kg each year in the U.S. alone (Kiely, et. al., 2004). An unquantifiable but considerable portion of this total does not reach or leaves its target; this proportion may contaminate air or water, may be transformed in the soil/air/water system, and may come into contact with non-target biological systems. The continued responsible use of conventional and emerging crop protection chemistries will require a mechanistic understanding of their fate and effects (beginning at the molecular level) and integration of this basic knowledge to develop a fuller understanding of their behavior in agroecological systems. The W-45 project focuses on building collaborations between land-grant extension specialists, researchers, USDA-ARS scientists, and institution representatives from basic and applied research disciplines to identify and develop appropriate research and strategies for minimizing adverse impacts to humans and the environment resulting from agrochemical use. This multidisciplinary effort enables technology transfer and opportunities for region-wide collaboration on complex environmental fate and effects issues that are beyond the scope of a single State Agricultural Experiment Station or ARS. The outcomes of the W-45 project are deliverables that can be utilized by regulatory agencies, growers, agrochemical manufacturers and applicators, and regional agricultural commodity groups for making prudent pesticide management decisions. In partnership with CSREES, other research institutions and agencies, and the Cooperative Extension Service, replacement of the W-45 multistate research project will further enable meaningful multistate collaborations for problem-solving on high-priority research topics (as identified in CSREES Strategic Plan for FY 2004-2009) while enhancing environmental stewardship.
A better understanding of off-target movement via volatilization, runoff, and leaching, and the acute and sublethal effects at the ecosystem level are essential for determining risks to biota in the surrounding environment and for characterizing human occupational and non-occupational exposures. Currently, quantifying exposure remains the weak link for evaluating risks associated with human and environmental health. Collaborations between W-45 scientists at the University of California (Davis and Riverside), Washington State extension specialists, and state health regulators will have enormous implications in addressing occupational exposures. This work will include environmental and biological monitoring of a variety of work tasks of pesticide handlers and harvesters of treated crops. These data will serve to clarify the extent of risk resulting from exposure and provide exposure data for more objective establishment of field entry intervals and the effectiveness of personal protective equipment. This project will also evaluate the adequacy of commercial blood cholinesterase kits used by clinical testing laboratories for monitoring farm worker exposure.
Information sharing will be vital for state health agencies to formulate appropriate baseline exposure criteria and risk management policies. Off-target fumigant emissions remain a primary source of non-occupational exposure at the individual and community health level as underscored in the California Office of Environmental Health Hazard Assessment (OEHHA) community health studies at Lompoc, California, which suggested an increased incidence of certain respiratory illnesses and lung and bronchus cancers in the Lompoc area (Wisniewski et al., 1998). To reduce non-occupational inhalation exposures, W-45 members at the USDA-ARS in Riverside, CA and the University of Florida are taking leading roles in developing novel technologies to reduce atmospheric emissions of fumigants while providing adequate dispersion in the root zone to achieve good pest-control efficacy. Reducing volatilization by covering the soil surface during fumigation with plastic tarps or with newly-developed water soluble, biodegradable, and non-toxic reactive surface barriers will have enormous benefits for crop production practices throughout the United States by increasing fumigant efficacy, reducing chemical use, and substantially minimizing inhalation exposures to surrounding communities.
Monitoring studies have indicated widespread contamination of surface water and groundwater by herbicides and herbicide transformation products throughout the United States. Many states remain hesitant to register new pesticides unless explicit chemical leaching and runoff studies are performed using soil types and conditions typical of the region. Collaborative research among W-45 members will develop regional data on the environmental fate and movement of nutrients and new pesticides and their transformation products that are not currently available to regulatory agencies. This information will be important in accelerating and evaluating the conditional registration of environmentally safer alternative herbicides, and will aid in the development of best management practices to reduce the potential for surface and ground water contamination. This project will further advance water quality protection through education opportunities such as the Integrated Soil Nutrient and Pest (iSNAP) Water Quality Education Project and will provide technical training and resources to agricultural professionals on nutrient management and integrated pest management practices that protect water quality.
Turf management (including golf courses, parks and recreation facilities, sports fields, and home residential lawns) typically involves very intensive agrochemical use patterns. Researchers at Mississippi State University will collaborate with USDA-ARS scientists in St. Paul, MN to identify environmental factors and management practices influencing agrochemical losses from turf by runoff and to develop deterministic models to estimate the impact of new and existing chemistries on aquatic systems under suburban management practices. The data gained from this research can be used to identify which compounds exceed the environments natural attenuative capacity and to develop best management practices to reduce the movement of these pesticides to non-target aquatic systems.
There is growing evidence that historical and current use pesticides may undergo atmospheric long-range transport (including trans-Pacific atmospheric transport) and deposition to remote high latitude and high elevation ecosystems in the U.S. These pesticides may originate in North America or may be present in Eurasian air masses. This project will measure historical and current use pesticides to study the fate of these compounds in sensitive, high elevation ecosystems. Research results will influence global regulatory strategies on the use of pesticides in developing countries and will aid the U.S. National Park Service in managing exposure to pesticides due to long-range atmospheric transport.
The environmental fate of airborne organic pollutants, i.e., their atmospheric lifetime, can often be governed by their distribution between the gas and particle phases. For chemicals that are relatively persistent in the atmosphere, removal of the particle-bound fraction by dry deposition or scavenging by rain, snow and fog may be the most important depositional process. However, previous results developed by the USDA-ARS indicated that polar chemicals do not follow established prediction models for partitioning between the gas and particle phases. Over the next five years, collaborations among W-45 members at the USDA-ARS in Beltsville, MD, the University of Nevada, and Washington State University will be critical for better understanding complex atmospheric interactions of volatile organic pollutants. Their collaborative expertise, together with novel atmospheric reaction vessels and key instrument resources, will strengthen atmospheric research in evaluating and modeling distributional phenomena and gas-phase chemical reactivity, which is required for assessments of human and environmental exposure.
Environmental exposures from the improper disposal of unwanted pesticides and rinse water from pesticide containers and application equipment can trigger regulatory actions that have immediate and irreversible consequences for agriculture. W-45 scientists and extension specialists are developing efficient, fast, low cost, and easily operated technology that can be utilized by growers, commercial applicators, and others for treating highly-concentrated pesticide wastewater onsite. This level of on-site treatment takes on added significance since the occurrence of agrochemicals above detectable concentrations in surface waters may have important regulatory consequences for threatened salmonid species in the western states.
At the watershed level, there is also an immediate need for multistate involvement to understand the consequences of agricultural and urban agrochemical surface water discharges, particularly in the Pacific Northwest where certain salmonid species are listed as threatened under the Endangered Species Act of 1973. The recent implementation of EPAs Endangered Species Protection Program (ESPP) will place greater pressure on agriculture to control agrochemical discharges at the watershed level. Over the next 5 years, W-45 scientists and extension specialists will investigate aquatic exposures to agrochemicals. This work will lead to the formulation of watershed management plans that can adequately protect salmonid species while avoiding an unnecessary burden on agriculture and other pesticide users. The results of this work will aid EPA in forming prudent biological opinions on salmonid health and assist in better defining aquatic exposure parameters in state plans such as the Oregon Plan for Salmon and Watersheds and the anticipated Washington State Endangered Species Protection Plan for Pesticide Use. The ESPP may also place greater pressure on agriculture to understand the influence of sublethal effects of agrochemicals on threatened and endangered migratory avian species. W-45 scientists are evaluating the effect of acute low-dose exposure to various cholinesterase inhibitor agrochemicals on homing pigeon migratory behavior and fertility. This project will provide insights into the effects of acute low-dose exposure on pigeon fertility and fetal development that can have implications at the molecular level for threatened and endangered migratory avian species.
Since its early beginnings, W-45 has effectively responded to western region grower and stakeholder concerns for understanding the effects of post-application pesticide transport and fate, and the toxicological implications of agrochemical uses. Today, the work of W-45 scientists extends well beyond the western region boundary. This growing collaboration among chemists, biologists, toxicologists, and ecologists with expertise in the basic and applied sciences remains essential for responding to emerging chemical fate and effect issues in accordance with the need for realistic human and environmental exposure information under the provisions of the Endangered Species Act and the Food Quality Protection Act. The strong collaborations among land-grant university scientists and extension specialists together with USDA agricultural research scientists provide a unique amalgamation of research and extension capabilities. This project will continue in its goal to advance science-based strategies to prevent or mitigate unacceptable adverse impacts on humans and the environment while affording joint research, extension, and training opportunities through multistate collaboration and shared use of key research and educational resources.
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