Initial findings allay concerns about hormone runoff in soil, water
For close to 20 years concerns have grown over whether human and animal hormonal supplements could contaminate soil and water. Of particular interest is the fate of these compounds and their naturally produced counterparts, which are found in animal waste and used as a fertilizer.
For two years, University of Nebraska-Lincoln beef specialist Terry Mader has been trying to answer those concerns. Mader, along with a team of other scientists, has been cooperating on a cattle feeding project to study this issue.
The U.S. Environmental Protection Agency, which has funded the project, was particularly interested in knowing whether hormonal compounds such as estrogen, progesterone and androgen, which are derived from urine and feces, can run off into waterways.
"Preliminary data suggest that at least a portion of these concerns are unfounded," Mader said.
Ecologists are concerned that hormonal contamination in the waterways actually can change the sex of some species of fish, resulting in an imbalance in male-female ratio.
Hormonal supplements frequently are used in feedlots and have been shown to increase average daily weight gain by 20 percent, increase feed utilization by 10 percent and decrease the cost of achieving that gain by 10 percent, resulting in lower beef costs for the consumer, the Institute of Agriculture and Natural Resources scientist said.
The goal of UNL's research is to determine the extent naturally produced and synthetic hormonal compounds are excreted and whether those compounds stay biologically active in soil and water. The three-year research project is about at its midpoint.
To conduct the research, Mader used 100 heifers in each of two years at UNL's Haskell Ag Lab in Concord. For comparison purposes, 50 percent were given the hormonal supplements and 50 percent were not. The feeding trials were conducted to produce the waste.
Liquid waste that entered settling basins was sampled as was solid waste that was stockpiled and composted and later used as fertilizer on crops. A rain simulator was used to get runoff from the fields, which then was analyzed.
So far, 10 percent to 15 percent of the waste samples have been analyzed with no abnormal levels of the hormonal compounds found. The compounds have a natural decay rate, but the rate may vary depending on the compounds, manner of soil application and the environment. Previous studies have shown mixed results in rates of decay, with some compounds decaying rapidly and others slow.
"The preliminary findings would suggest there is significant amount of breakdown of these compounds in the body before they are excreted and there is further degradation in the deposited animal waste," Mader said.
However, since most of these compounds also are produced by plants and other life forms, some of the compounds are expected to be found in baseline soil and water samples, he said.
Mader said that to his knowledge, no data exists that has shown significant long-term and/or permanent changes in the aquatic species or environment due to naturally produced or manmade hormonal compounds derived from animal or human waste. However, it is important that the fate of these compounds is fully understood and the environment is protected, he said.