A quantitative method for assessing the sensitizing potency of low molecular weight chemicals using a local lymph node assay: employment of a regression method that includes determination of the uncertainty margins

Risk assessment of sensitizing chemicals requires, besides hazard identific ation, the assessment of potency. To examine the sensitizing capacity of lo w molecular weight chemicals, a murine local lymph node assay (LLNA) was us ed. The sensitizing capacity of known allergens was quantified by dose-resp onse modeling. At a stimulatory index (SI) of 3, the corresponding estimate d concentration was calculated (EC,), together with a confidence interval t o take account of the quality of the particular data set. We tested ten all ergens (ethyl-p-aminobenzoate (benzocaine), diethylamine (DEA), 2,4-dinitro chlorobenzene (DNCB), 2-mercaptobenzothiazole (MBT), 4-ethoxymethylene 2-ph enyl oxazol-5-one (oxazolone), phthalic anhydride (PA), toluene diisocyanat e (TDI), trimellitic anhydride (TMA), tetramethylthiuramdisulfide (TMTD) an d zincdimethyldithiocarbamate (ZDMC)). Oxazolone showed the strongest sensi tizing potency followed in this order by DNCB, TDI, TMA, PA, TMTD, ZDMC, MB T, benzocaine and DEA. The approach performed in this study is a way to acc urately assess the potency of sensitizing chemicals and thus a possibility for classification. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.