Concerns that toxicological test guidelines may not optimally detect effects on the endocrine system have lead to proposals to enhance the current sub-acute rodent OECD Test Guideline No. 407 (OECD 1995). The efficacy of the modified enhanced (phase 2) protocol (OECD 2000) was investigated in a worldwide effort by 13 laboratories using 10 endocrinologically-active compounds. This test conducted studies with ethinylestradiol. The main objectives of the study were (1) to determine which of the current and/or additional parameters will detect the endocrine effects of ethinylestradiol reliably and sensitively, and (2) to assess intra-laboratory variability by performing two identical studies in parallel. In addition, and outside the scope of the enhanced protocol, effects of ethinylestradiol on metabolizing liver enzymes were investigated.
Andrews P, Freyberger A, Hartmann E, Eiben R, Loof I, Schmidt U, Temerowski M, Folkerts A, Stahl B, Kayser M (2002). Sensitive detection of the endocrine effects of the estrogen analogue Ethinylestradiol using a modified enhanced subacute rat study protocol (OECD Test Guideline no 407). Arch Toxicol 76:194-202 Andrews P, Freyberger A, Hartmann E, Eiben R, Loof I, Schmidt U, Temerowski M, Becka M (2001). Feasibility and potential gain of enhancing the subacute rat study protocol (OECD test guideline no. 407) by additional parameters selected to determine endocrine modulation. A pre-validation study to determine endocrine-mediated effects of the antiandrogenic drug flutamide. Arch Toxicol 75:67-73 Hofmann A., The enhanced subacute toxicity test OECD TG 407 for the detection of endocrine active chemicals. Comparison with toxicity tests of longer duration. Presentation given to the 6th LRI Workshop, 17-18 November 2004, Brussels