• photobacteria;
  • Vibrio fischeri;
  • luminescence;
  • Flash method;
  • Microtox;
  • EILATox-Oregon Workshop;
  • toxicity;
  • ec50


The Flash test, which can be used to measure the toxicity from clear, turbid and coloured samples with identical protocol, was used in the EILATox-Oregon Workshop. During the workshop, 17 synthetic samples and three environmental samples were tested. In the Flash method the photobacteria Vibrio fischeri are initially dispensed on top of the sample and the light output of the bioluminescence reaction is recorded at a rate of several readings per second. The change in the light production was measured at two points: 30 s and 30 min after exposure at room temperature. Toxicity calculations were done by using either the peak height of the sample or the peak height of the control sample (maximum signal at 0–2 s). When the peak height of the sample is used as a reference, the colour and turbidity effect of solid particles are taken into account throughout the whole measurement period. In the EILATox-Oregon Workshop toxicity was seen in samples 1 (chlordimeform), 4 (phosdrin), 5 (HgCl2), 6 (sodium arsenite), 8 (metham sodium), 12 (p-chlorophenol), 14 (sodium selenite) and 17 (MNNG). Only samples 1, 4 and 12 showed different ec50 values between different calculations of toxicity. The ec50 values were calculated and compared with the ec50 values of Microtox derived from the literature. The Flash test will not replace the standardized photobacteria test, but is the advanced version of it and is needed when the sample matrix is complex and when speed and low costs are required. Copyright © 2004 John Wiley & Sons, Ltd.