17β-estradiol and testosterone in soil and runoff from grasslands amended with broiler litter

In 1998, the U.S. poultry industry generated almost 12 million Mg of broiler (Gallus gallus domesticus) litter, most of which was applied to grasslands as fertilizer. This litter contains appreciable concentrations of estradiol and testosterone, sex hormones of environmental concern. We measured estradiol and testosterone concentrations in soil and runoff water from large (0.8 ha) grazed and ungrazed grasslands amended with broiler litter. Samples were analyzed by enzyme immunoassay. In runoff, background concentrations were 50 to 150 ng estradiol L-1 and 15 to 125 ng testosterone L-1. No significant differences were observed in runoff concentrations between hayed and grazed plots (p = 0.1). Therefore, grazing animals did not contribute hormones to runoff. When litter was applied, runoff concentrations were 20 to 2530 ng estradiol L-1 and 10 to 1830 ng testosterone L-1, depending on litter application rate and time between application and runoff. In soil, the background concentration for estradiol was 55 ng kg(-1). Depending on litter application rate and time from application, the estradiol concentration in soil increased up to 675 ng kg(-1). Testosterone followed a similar trend; however, concentrations of testosterone were significantly higher in grazed than in hayed plots (p = 0.1). These results show sizable edge-of-field losses of estradiol and testosterone from broiler litter-amended grasslands, and are the first studies to measure estradiol and testosterone in soil. Future research needs to examine the persistence and degradation of estradiol and testosterone in broiler litter, soil, and runoff.