Sound oral to inhalation extrapolation factors (EFs) for human health risk assessment

Introduction

• Route to Route extrapolation (R2R) is required if no in vivo data on the appropriate route are available
• R2R needs to be performed in a case by case approach for the individual substance
• Criteria for R2R are: only systemic toxicity; critical toxic effect is not a local effect; no significant differences in metabolism in both routes; first pass effect is minimal; the substance is soluble in body fluids; account for differences in absorption (ECHA default factor of 2)