CYTOTOXICITY OF 12 CHEMICALS OF KNOWN HUMAN AND ANIMAL SKIN IRRITATION POTENTIAL IN HUMAN KERATINOCYTE CULTURES

12 chemicals were selected for cytotoxicity testing, based on a report of a collaborative study (EC Project 86E3-063/86-460) that compared in vitro cytotoxicity in animal cell models with animal irritation and non-invasive human in vivo data. Neutral red (NR) and acid phosphatase (AP) activity were chosen as endpoints of cytotoxicity. AP activity has been shown to be a specific indicator of cytotoxicity in keratinocytes. NR(50) values (concentration that produces a 50% reduction in NR uptake compared with controls) and AP((peak)) values (concentration at which a peak activity occurs) were calculated for each chemical. Both in vitro assays exhibited good correlations with the animal irritation data. Poor correlations were obtained for comparison of the cutaneous blood flow volume data. The data presented provide useful information on the relationship between in vivo skin irritation and in vitro experimental models.