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ECHA’s Advice on Determining Dose Levels in Toxicity Testing

Date: 18 March 2022

ECHA has recently published guidance on dose setting for repeated-dose toxicity studies. The new guidance advices to justify dose setting for all doses, including spacing. The dose setting should be determined by range-finding studies, not by acute toxicity studies or toxicokinetics. ECHA considers 2- to 4-fold intervals to be optimal. For larger intervals between dosages, e.g. 6- to 10-fold, ECHA recommends adding a fourth test group. The length of the range-finding studies requires to be at least 7 days for subacute studies and at least 14 days for subchronic studies. The range-finding studies should be provided in separate endpoint study records (ESRs).

If sensitivity differs between sexes, they should be tested at different doses.

Sexual function and fertility should be prioritised in the study design of the OECD TG 443, thus dose levels should not be reduced to get enough offspring for the assessment of developmental toxicity.

For more information, please visit: https://www.echa.europa.eu/-/new-advice-for-determining-dose-levels-in-toxicity-testing