Premium
A toxicity identification evaluation approach to studying estrogenic substances in hog manure and agricultural runoff
Author(s) -
Burnison B. Kent,
Hartmann Andreas,
Lister Andrea,
Servos Mark R.,
Ternes Thomas,
Van Der Kraak Glen
Publication year - 2003
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/02-437
Subject(s) - equol , estrone , manure , bioassay , estrogen , metabolite , endocrine disruptor , chemistry , vitellogenin , environmental chemistry , biology , hormone , endocrine system , endocrinology , biochemistry , agronomy , ecology , daidzein , genistein , gene
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 17β‐estradiol (E 2 ) 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 E 2 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.