ESTP comments on the draft updated OECD test guideline 407.

Area of Science:

• Toxicology
• Endocrinology
• Chemical Safety Assessment

Background:

• The Organisation for Economic Co-operation and Development (OECD) Test Guideline (TG) 407, a repeated dose 28-day oral toxicity study in rodents, is undergoing revision.
• The revision aims to incorporate new endpoints specifically designed to detect endocrine activities of chemicals.
• These new endpoints may impact existing core endpoints within this study type.

Purpose of the Study:

• To evaluate the proposed revisions to the OECD TG 407 guideline.
• To assess the implications of new endocrine activity endpoints on the established study protocol.
• To consider the scientific and practical aspects of proposed methodical changes.

Main Methods:

• Expert group review by the European Society of Toxicologic Pathologists (ESTP).
• Discussion of specific methodological changes: necropsy timing in females, synchronized blood collection for clinical chemistry and hematology, thyroid gland weighing, and detailed prostate lobe weighing.
• Consideration of potential alternative approaches.

Main Results:

• The revision focuses on enhancing the detection of endocrine disruptors.
• Methodical changes, such as specific necropsy timing and organ weighing, were critically evaluated.
• Both advantages and disadvantages of proposed changes were considered by experts.

Conclusions:

• The revised OECD TG 407 aims to improve the assessment of chemical endocrine activity.
• Careful consideration of methodological changes is crucial for maintaining scientific validity and practicality.
• The ESTP's input highlights the importance of expert evaluation in guideline development.