DOSE DEPENDENT BENEFICIAL OR ADVERSE EFFECT OF ESTRADIOL IN NORMAL AND CADMIUM TREATED AMPHIBIAN EMBRYOS

JORGE HERKOVITS, CRISTINA SILVIA PEREZ COLL1,2 AND OSVALDO FRIDMAN1

Baltimore, Maryland

Congreso; XXVI Annual meeting SETAC N. A.; 2005

Setac N. A.

Because the large number of inorganic and organic chemicals with hormonelike activity, endocrine disruption is of major concern from an ecotoxicological perspective. In previous studies we reported the toxicity of estradiol and its adverse effect on cadmium treated amphibian embryos. The main purpose of this study is to report that the beneficial or adverse effect of E2 depend on its concentration both for normal and cadmium treated embryos. Batches of 10 embryos by triplicate at complete operculum stage were maintained in 40 ml of  Amphytox Solution (AS) and treated with (A) 0.2 mg/L Cd2+, (B) 0.2 mg/L Cd2+ and 0.1µmol/L E2, (C) 0.2 mg/L Cd2+ and 1µmol/L E2, (D) 0.2 mg/L Cd2+ and 10µmol/L E2, (E) 0.1µmol/L E2, (F) 1 µmol/L E2, (G) 10µmol/L E2 and (H) control embryos maintained in AS. The lethality was registered daily and in the case of this study no food was administrated during the whole experimental period. The lethality (in percentage) at 96 and 168 hr of exposure were (A) 13.3 and 86.7; (B) 3.3 and 6.7; (C) 30.0 and 36.7; (D) 50.0 and 100; (E) 13.3 and 20.0; (F) 6.7 and 10.0; (G) 23.3 and 93.3; (H) 3.3 and 26.7 respectively. The results point out that 0.2mg Cd2+/L exert 13.3 and 86.7% of lethality within acute and short-term chronic exposure respectively, and E2 exert a beneficial or adverse effect on control as well as cadmium treated embryos depending on the dose administered. Low level exposure (0.1 µmol/L E2) exert a maximal beneficial effect, middle concentration (1 µmol/L E2) exert a slight beneficial effect and high concentrations (10 µmol/L E2) exert an adverse effect both in control and cadmium treated embryos. Taking into account that the estrogenic potencies of xenobiotics are usually 1,000-fold lower than those observed for estradiol, eventual beneficial or adverse effects due to xenoestrogenic substances will depend on their concentration in the environment.