Steroid Estrogens and Estrogenic Activity in Farm Dairy Shed Effluents
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Estrogenic contamination of waterways is of world-wide concern due to the adverse effects observed in aquatic biota. Recently, wastes from agricultural activities have been identified as likely sources of steroid estrogens released into the environment. Wastes from dairying activities are of particular concern in New Zealand. This project included development of analytical methods to measure free and conjugated estrogens, measurement of estrogens from the source to receiving environments and an investigation of effluent treatment technologies. The analytical method developed in this study was based on GC-MS measurement of free estrogens (17α-estradiol (17α-E2), 17β-estradiol (17β-E2) and estrone (E1)) and LC-IT-MS measurement of their sulfate-conjugates (17α-E2-3S, 17β-3S, E1-3S) in raw and treated farm dairy shed effluents (DSE). Effluents from farms in the Canterbury and Waikato Regions, two regions where dairy farming is the dominant land-use, were collected and analysed. All effluents demonstrated high concentrations of steroid estrogens, particularly 17α-E2 (median 760 ng/L). Estrogenic activity was also elevated, at up to 500 ng/L 17β-E2 equivalents using the E-Screen, an in vitro cell proliferation bioassay. Comparison to the chemical data indicated that for most samples, the highest proportion of estrogenic activity was derived from steroid estrogens naturally excreted by dairy cows. Conjugated estrogens were measured in several raw effluent samples, at similar concentrations to those of free estrogens, particularly E1. Dairy effluent treatment systems reduced free estrogen concentrations by 63-99% and reduced estrogenic activity by up to 89%. In spite of high removal efficiencies, estrogens remained elevated in the treated effluents that are discharged into waterways. Steroid estrogens and estrogenic activity were detected in streams and groundwater in areas impacted by dairy farming. Although concentrations were generally low, in two streams the concentrations were above levels regarded as safe for aquatic biota (<1 ng/L). The results demonstrate that dairy effluents are indeed a major source of estrogens to the environment and to waterways.