title: Environmental health impacts of equine estrogens derived from hormone replacement therapy.
abstract: Many factors have been considered in evaluations of the risk-benefit balance of hormone replacement therapy (HRT), used for treating menopausal symptoms in women, but not its potential risks for the environment We investigated the possible environmental health implications of conjugated equine estrogens (CEEs), the most common components of HRT, including their discharge into the environment, their uptake, potency, and ability to induce biological effects in wildlife. Influents and effluents from four U.K. sewage treatment works (STWs), and bile of effluent-exposed fish, were screened for six equine estrogens. In vitro estrogen receptor (ER) activation assays were applied in humans and fish to compare their potencies, followed by in vivo exposures of fish to equine estrogens and evaluation of bioaccumulation, estrogenic responses, and ER gene expression. The equine estrogen equilenin (Eqn), and its metabolite 17beta-dihydroequilenin (17beta-Eqn), were detected by tandem GC-MSMS in all STW influent samples and 83% of STW effluent samples analyzed, respectively, at low concentrations (0.07-2.6 ng/L) and were taken-up into effluent-exposed fish. As occurs in humans, these estrogens bound to and activated the fish ERs, with potencies at ERalpha 2.4-3490% of thatfor 17beta-estradiol. Exposure of fish for 21 days to Eqn and 17beta-Eqn induced estrogenic responses including hepatic growth and vitellogenin production at concentrations as low as 0.6-4.2 ng/L. Associated with these effects were inductions of hepatic ERalpha and ERbeta1 gene expression, suggesting ER-mediated mechanism(s) of action. These data provide evidence for the discharge of equine estrogens from HRT into the aquatic environment and highlight a strong likelihood that these compounds contribute to feminization in exposed wildlife.
authors: School of Biosciences, University of Exeter, Exeter, United Kingdom. c.r.tyler@exeter.ac.uk
authors: Charles R
authors: CR
authors: Tyler
authors: Amy L
authors: AL
authors: Filby
authors: Lisa K
authors: LK
authors: Bickley
authors: Rob I
authors: RI
authors: Cumming
authors: Richard
authors: R
authors: Gibson
authors: Pierre
authors: P
authors: Labadie
authors: Yoshinao
authors: Y
authors: Katsu
authors: Katherine E
authors: KE
authors: Liney
authors: Janice A
authors: JA
authors: Shears
authors: Vanessa
authors: V
authors: Silva-Castro
authors: Hiroshi
authors: H
authors: Urushitani
authors: Anke
authors: A
authors: Lange
authors: Matthew J
authors: MJ
authors: Winter
authors: Taisen
authors: T
authors: Iguchi
authors: Elizabeth M
authors: EM
authors: Hill
mesh_terms: D000818:Animals; D004781:Environmental Exposure; D004782:Environmental Health; D047628:Estrogen Receptor alpha / Q000378:metabolism; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000737:chemistry / Q000633:toxicity*; D005399:Fishes / Q000378:metabolism; D006736:Horses / Q000378:metabolism*; D006801:Humans; D012722:Sewage; D006113:United Kingdom; D014865:Waste Disposal, Fluid
chemical_list: D047628:Estrogen Receptor alpha; D004967:Estrogens; D012722:Sewage