Analysis of steroid hormones in a typical dairy waste disposal system.

The environmental loading of steroid hormones contained in dairy wastes may cause an adverse effect on aquatic species. To better assess the potential risks of hormone contamination resulting from land application of dairy wastes, various steroid hormones were determined in a typical dairy waste disposal system. Quantitative methods using gas chromatography/mass spectrometry (GC/MS) were developed to monitor low levels of steroid hormones in complex solid and liquid samples contaminated with dairy manure. The preparation method for wastewater analysis consisted of solid-phase extraction and purification steps, which minimized interference from the sample matrices and achieved low detection limits for the studied hormones. In the dairy wastewater and lagoon water, three endogenous hormones-17alpha-estradiol, 17beta-estradiol, and estrone-were detected. The concentration of 17alpha-estradiol in fresh milk parlor effluent rapidly decreased along the wastewater disposal route, whereas the concentration of estrone increased along this same pathway. This suggests that 17alpha-estradiol was readily oxidized to the metabolite estrone. Levels of total steroid hormones in the sequencing lagoon water were approximately 1-3 orders of magnitude lower than those in the fresh dairy wastewaters, indicating significant removal of these hormones during the transport of dairy wastewater from source to field. In solid dairy waste samples, four steroid hormones were identified and quantified. Increasing the piling time of solid wastes and increasing the residence time of wastewater in sequencing lagoons are suggested to be economical and efficient agriculture practices to extend the degradation time of hormone contaminants and thereby reduce the hormone load to the environment.