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Livestock Links: Examining the role of baceria in breaking down steroid sex hormones

February 5, 2010

[Source: Sarah Lupis, Institute for Livestock and the Environment and Thomas Borch, Assistant Professor, Soil and Crop Sciences/Chemistry for CLA’s Today, an e-newsletter of the Colorado Livestock Association]

Water quality has been a hot topic in the news lately, with both recent articles in national newspapers and a recent lawsuit that demands the Environmental Protection Agency establish water-quality criteria for a previously unregulated class of chemicals—endocrine-disrupting chemicals, including steroid sex hormones, which effect growth, development, and reproduction (all parts of the “endocrine system” of living organisms).

Both natural and synthetic hormones are present in the environment. All living creatures produce hormones which are also found in the feces and urine they produce. Synthetic hormones may be used in birth control and cancer treating drugs for humans and both synthetic and natural hormones are sometimes used to promote growth and production in livestock. Hormones make it into streams, lakes, and ground water from a variety of sources. Often, it is hard to pin down their origin. Potential sources of hormones in the environment include runoff from agricultural fields that have been fertilized with manure or biosolids, confined animal feeding operation (CAFO) effluent, and municipal waste water treatment facilities. In some situations, exposure to these can have lasting and profound effects on fish, frogs, and other wildlife that live in aquatic systems. For example, exposed fish may have both male and female reproductive organs. If exposed through drinking water, humans may potentially be harmed by these chemicals.

Little is known about what happens to hormones once they enter the natural environment. Many factors, such as temperature, oxygen, and pH influence how these compounds break-down. To better understand some of these questions, Thomas Borch, Lawrence Goodridge, and Jessica Davis, all faculty with CSU’s Institute for Livestock and the Environment, have been investigating how hormones in swine manure break down in a laboratory setting—one that mimics natural conditions. They found that the bacteria naturally present in the swine manure would break down the hormones under a wide range of environmentally relevant conditions. Here’s how it works: researchers take a small sample of swine manure and separate out the bacteria living in it. Then, they grow, or “culture,” these bacteria in a laboratory environment kept at conditions similar to that found in nature (i.e., similar pH, temperature, and oxygen are present). The bacteria are fed a diet containing sugar and nutrients, which they eat voraciously, causing them to produce enzymes. These enzymes then get to work on the hormones, breaking them down into new chemical compounds.

The resulting degradation products, although less potent than the parent compounds, are still themselves a type of hormone and may still have the potential to cause harm (i.e., disruption of the endocrine system) to wildlife in the natural environment.

Research on hormones is ongoing at the CSU’s Institute for Livestock and the Environment, both in the lab and in the field. Additional research projects will help scientists understand what the bacteria in manure will do to hormones in long-term studies and how rainfall events in real-world settings impact hormone run-off from agricultural soils fertilized with biosolids.

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