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University of Georgia Receives EPA Grant to Study Pollution from Hormones in Chicken Waste


The University of Georgia (UGA) received an EPA grant totaling $695,620 today to study the environmental fate and transport of hormones in broiler chicken litter.

Broilers are chickens less than 13 weeks old, constituting virtually all commercially produced chickens, and their litter is a mixture of manure, feathers, feed, water and bedding. Broilers produce natural hormones, including higher amounts of estradiol and testosterone than other animals, which become concentrated in litter. Litter is often recycled as compost, fertilizer, cattle feed and even biofuel, and the hormones can seep into ground and surface water and soil.

Nationally, many broilers are raised in concentrated animal feeding operations (CAFOs). These are facilities where animals are confined and fed for 45 or more days per year that also exceed a size threshold (for broilers, where over 125,000 are raised), exhibit certain water discharge characteristics or are designated by a regulatory official as contributing significantly to surface water pollution. Due to the volume of waste generated, CAFOs pose risks to the environment and public health. Besides hormones, litter contains nutrients and pathogens that must be controlled to avoid contaminating soil and water sources.

“Preventing and managing pollution from large-scale animal feeding operations is a major priority for EPA, especially in the Southeast,” said Jimmy Palmer, EPA Regional Administrator in Atlanta. “The results from this study will help us better protect ground and surface waters from contamination associated with hormones in waste from concentrated animal feeding operations.”

Through the project, UGA researchers will first determine the concentration of hormones in different classes of litter. Fertilizer is produced from litter using a method known as “deep stacking,” where several feet of litter is stacked for weeks until the action of bacteria raises the temperature and kills any pathogens. UGA will determine whether deep stacking changes the concentration of hormones in litter. Researchers will also investigate the transport, runoff and decomposition of hormones in litter applied as fertilizer.

“This project will allow us to identify the concentration of hormones among different broiler litter types, which vary depending on the broiler growth period and the type of bedding material used (i.e., sawdust, pine shavings, rice or peanut hulls, crushed corn cobs, sand, etc.), among other things,” said Dr. Miguel Cabrera, the principal UGA investigator. “The study will better focus our research efforts to reduce hormone concentrations and will also help identify management practices for broiler litter.”

According to a U.S. Department of Agriculture (USDA) report on broiler production and value published in April, Georgia produced 1.4 billion broilers—more than any other state—valued at $2.7 billion in 2006. Georgia produces roughly 15 percent of the country’s broilers annually.

Two departments within UGA’s College of Agricultural and Environmental Sciences and their Agricultural and Environmental Services Laboratory will sample broiler litter and stack houses and perform hormone analysis. Field studies will be carried out by the Department of Crop and Soil Sciences. Rainfall simulation studies to evaluate surface runoff from grasslands fertilized with broiler litter will be carried out in collaboration with USDA’s Agricultural Research Service in Watkinsville, Ga.

The EPA funded this project as part of its Science to Achieve Results program. The results of this research will improve estimates of the occurrence and risks of steroid hormones associated with animal waste. Further the research is expected to help in the development of new or improved animal waste handling systems and risk management options for steroid hormones in animal waste.

To read the full text of the grant opportunity through which this project was funded, go to For more general information about environmental impacts from concentrated animal feed operations (CAFOs) and associated guidelines, visit


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