OECD GUIDELINES FOR THE TESTING OF CHEMICALS

2 In 1998, the OECD initiated a high-priority activity, to revise existing Test Guidelines and to develop new Test Guidelines for the screening and testing of potential endocrine disruptors (8). One element of the activity was to update the existing OECD guideline for “repeated dose 28-day oral toxicity study in rodents” (TG 407) by parameters suitable to detect endocrine activity of test substances. This procedure underwent an extensive international program to test for the relevance and practicability of the additional parameters, the performance of these parameters for chemicals with (anti)oestrogenic, (anti)androgenic, and (anti)thyroid activity, the intraand interlaboratory reproducibility, and the interference of the new parameters with those required by the prior TG 407. The large amount of data thereby obtained has been compiled and evaluated in detail in a comprehensive OECD report (9). This updated Test Guideline 407 is the outcome of the experience and results gained during the international test program. This TG 407 allows certain endocrine mediated effects to be put into context with other toxicological effects.