THE NEUTRAL RED UPTAKE ASSAY - COMMENTS ON THE RESULTS OF THE ISTITUTO-SUPERIORE-DI-SANITA IN THE EC HO VALIDATION-STUDY/

The neutral red uptake (NRU) assay was included, among others, in a va lidation study sponsored by the European Commission/British Home Offic e (EC/HO) study, for its reliability as an in vitro alternative to the Draize eye irritancy test. The test was performed in parallel by four laboratories (Istituto Superiore di Sanita [ISS], Microbiological Ass ociates, Hatano Research Institute and Kurabo Industries) on 60 select ed chemicals. The results obtained by the ISS are reported in this pap er. A poor rank correlation was obtained between the in vivo endpoint and the ISS in vitro results for the full set of chemicals and for the subsets, with the exception of surfactants, by an independent statist ics group. The same unsatisfactory results were obtained by the ISS gr oup when the rank correlation was calculated for compounds divided int o chemical groups. The performance of the NRU assay, as an alternative to the Draize eye irritancy test, is discussed.