Abstract
The Threshold of Toxicological Concern (TTC) concept developed generic human threshold values by grouping compounds into three structural groups (Cramer et al., 1978). The present thresh-olds for non-genotoxic compounds were derived based on the 5thpercentile NOEL (no observed effect level) of a broad database containing in vivo studies with oral exposure (Munro et al., 1996).Route to route extrapolation is a difficult topic in human health risk assessment. Especially the evaluation of local effects, which frequently occur after inhalation but rarely after oral exposure is a difficult topic. It is therefore of interest to determine the conditions under which the TTC concept can be applied to assess toxicity for non-oral exposure i.e. inhalation or dermal. In this lecture recent results on TTC values for inhalation exposure will be introduced and strength and limitations discussed (Carthew et al., 2009; Escher et al., 2010, CEFIC LRI-B8). Further an overview on recent TTC approaches for dermal exposure will be given (www.cosmostox.eu).