DEVELOPMENT OF A FIXED-DOSE APPROACH FOR THE FLUORESCEIN LEAKAGE TEST

To answer the question, ''How toxic is this material?'', rather than t he question more usually asked in in vitro toxicology, ''At what conce ntration does this material produce a given degree of toxicity?'', a t ired-dose approach has been developed with the FRAME fluorescein leaka ge (FL) test. Recovery from the initial cytotoxic effect was also note d sometimes, after the cells had been maintained in fresh medium for a further 72 hr. Chemicals rated R41 or R36 in vivo gave a level of FL above 20% immediately, and 66% or more 72 hr later (i.e. there was fur ther deterioration, rather than recovery). Acetaldehyde, when duplicat ed and tested either in Hanks' balanced salt solution or oil, showed g reater toxicity in the oil because of its high volatility. The chemica ls classified as no-label gave FL values below 12% immediately after e xposure, except Brij-35, which showed no further deterioration during the 72-hr period in fresh medium.