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Toxicological report Bio 464

E2. Toxicological report Bio 464. Background. E2 or 17 β - estradiol is derived from female estrogen hormone The most potent form of mammalian estrogen steroid E2 and its synthetic derivative are important and relevant in ecotoxicology. Background.

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Toxicological report Bio 464

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  1. E2 Toxicological report Bio 464

  2. Background • E2 or 17β- estradiol is derived from female estrogen hormone • The most potent form of mammalian estrogen steroid • E2 and its synthetic derivative are important and relevant in ecotoxicology

  3. Background • Synthetic form EE2 or ethinylestradiol synthesized from estradiol • EE2 is often used in oral contraceptives

  4. Physical Properties • Fine white crystalline powder or cream • EE2 is a hemihydrate (one molecule of water for every two molecules of EE2) EE2 E2

  5. Physical property • Solubility in water (low solubility)– • E2: 3.60 mg/l @ 27 deg C • EE2: 11.3 mg/l @ 27 deg C • Both are susceptible to photodegradation • EE2 more resistant to biodegradation

  6. Source into the Aquatic Environment • High level of E2 and EE2 often found in municipal, agricultural and industrial wastewater outfall • Human and excretion is a primary source of xenoestrogens in an aquatic environment • Increasing use of estrogen in medicine and farming contribute to E2 and EE2 being found in aquatic environment

  7. Mechanism of Action • At the cellular level, estrogens increase the synthesis of DNA, RNA, and various proteins in target tissues. Pituitary mass is also increased. • As a lipophilic hormone, it diffuses readily through cellular membranes to bind to estrogen receptors situated in the nucleus.

  8. Toxic effects • Effects of an acute dose is mild and self-limiting • LD50 > 5000 mg/kg in Rats via oral route • Both E2 and EE2 are considered endocrine disrupting chemicals • Carcinogenic • Study in rats show growth of tumors from chronic exposure • Chronic exposure in human increase risk of endometrial, breast, and certain liver cancers • E2 and EE2 have genotoxic effect on sperm cells

  9. Toxic effects in aquatic systems • Feminization shown in fish especially near wastewater outfall sites • Genotoxicity shown in male fish sperm • Stress response also shown to be affected • Cortisol levels were depressed in male fish • Effects not as pronounced in bivalves • susceptible to damage by estrogens at certain points in their gametogenesis process

  10. Metabolism • Estradiolis rapidly and completely absorbed from the gastrointestinal tract • Bioavailability is reported at 40% • Bioaccumulation is short term • In rats and in humans, in that both species transform these steroids mainly by (aromatic) 2-hydroxylation • Estradiolis primarily converted to estriol, which is the major urinary metabolite • Ethinylestradiol is excreted in urine and feces in a ratio of about 4:6

  11. Bibliography • V. Matozzoet al. Vitellogenin as a biomarker of exposure to estrogenic compounds in aquatic invertebrates: A review. EnvironmentInternational 34 (2008) 531–545 • W.J. Langston et al. Oestrogens and xeno-oestrogens in the aquatic environment. Journal of the Marine Biological Association of the United Kingdom (2005) • International Programme on Chemical Safety; Poisons Information Monograph: Ethambutol (PIM 221) (1997) Available from, as of May 19, 2005: http://www.inchem.org/pages/pims.html • IARC. Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/index.php p. V72 503 (1999) • E.L. Gregoraszczuk et al. Effects of estradiol, PCB3, and their hydroxylated metabolites on proliferation, cell cycle, and apoptosis of human breast cancer cells. Environmental Toxicology and Pharmacology 25 (2008) 227–233 • M. Teles et al. Biotransformation, stress and genotoxic effects of 17β-estradiol in juvenilesea bass (Dicentrarchuslabrax L.).Environment International 32 (2006) 470–477

  12. Bibliography • D.M. Papoulias et al. An in vivo model fish system to test chemical effects on sexual differentiation and development: exposure to ethinylestradiol. Aquatic Toxicology 48 (2000) 37–50 • C.M. Ciocan et al. Effects of estrogen exposure in mussels, Mytilusedulis, at different stages of gametogenesis.Environmental Pollution 158 (2010) 2977-2984 • M. Ann Rempel et al. Evaluation of relationships between reproductive metrics, gender and vitellogeninexpression in demersal flatfish collected near the municipal wastewater outfall of Orange County, California, USA. Aquatic Toxicology 77 (2006) 241–249

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