title: A toxicity identification evaluation approach to studying estrogenic substances in hog manure and agricultural runoff.
abstract: Spreading liquid manure on agricultural fields is a routine way of disposing of animal manure and optimizing the use of nutrients for crops. Limited studies suggest that these wastes may contain a variety of endocrine-disrupting compounds (EDCs) that may be released into aquatic environments through runoff. The purpose of this study was to apply a toxicity identification and evaluation approach to isolate and identify estrogenic compounds in hog manure. A recombinant yeast estrogen screen bioassay was used to detect estrogenicity of high-performance liquid chromatography--separated hog manure fractions. Further analytical analyses of the fractions and comparison to authentic standards resulted in the identification of the endogenous estrogens 17 beta-estradiol (E2) and estrone, and the phytoestrogen metabolite, equol. High levels of equol (6.9-16.6 ppm) were found to be present in manure that was stored for several months. The endocrine-disrupting potential of equol was characterized further by using fish hormone estrogen receptor (ER), sex hormone binding protein (SSBP), and goldfish androgen receptor (AR) radioligand binding assays. Equol was found to be approximately 1,000- and 200-fold less potent that E2 in competing for binding sites of the SSBP and ER, respectively. Equol's potency was 2,200-fold less than testosterone for the AR. Additional studies confirmed the presence of compounds with estrogenic activity in tile drain water after application of hog manure to an agriculture field. In this case, the contribution of equol to the total estrogenicity of the tile drain water was minimal relative to that of natural estrogens. Overall, this study indicates that further work is warranted to assess the impact that EDCs that originate from agricultural runoff may have on the ecology or physiology of exposed biota.
authors.affiliation: National Water Research Institute, Burlington, Ontario L7R 4A6, Canada. kent.burnison@ec.gc.ca
authors.forename: B Kent
authors.initials: BK
authors.lastname: Burnison
authors.forename: Andreas
authors.initials: A
authors.lastname: Hartmann
authors.forename: Andrea
authors.initials: A
authors.lastname: Lister
authors.forename: Mark R
authors.initials: MR
authors.lastname: Servos
authors.forename: Thomas
authors.initials: T
authors.lastname: Ternes
authors.forename: Glen
authors.initials: G
authors.lastname: Van der Kraak
mesh_terms: D000383:Agriculture; D000818:Animals; D001681:Biological Assay / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D060754:Equol; D004967:Estrogens / Q000032:analysis / Q000096:biosynthesis*; D007529:Isoflavones / Q000032:analysis / Q000633:toxicity*; D008372:Manure; D011944:Receptors, Androgen / Q000187:drug effects / Q000502:physiology; D011960:Receptors, Estrogen / Q000187:drug effects / Q000502:physiology*; D012037:Refuse Disposal; D013552:Swine; D014873:Water Pollutants / Q000633:toxicity*; D015003:Yeasts
chemical_list: C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D004967:Estrogens; D007529:Isoflavones; D008372:Manure; D011944:Receptors, Androgen; D011960:Receptors, Estrogen; D014873:Water Pollutants; D060754:Equol