Evaluation of route-to-route extrapolation factors based on assessment of repeated dose toxicity studies compiled in the database RepDose ® .

•R2R extrapolation factors (oral-to-dermal and oral-to-inhalation) are derived based on no/lowest effect levels (NOELs/LOELs) in the Fraunhofer RepDose® database.•R2R extrapolation oral-to-inhalation: the analysis is based on a big dataset consisting of 246 study pairs on 110 chemicals.•Extrapolation factors and associated uncertainties are evaluated.•An EF of 3 for the extrapolation oral-to-inhalation is proposed. It covers also the uncertainty that unexpected local effects may occur in an inhalation study.