There is a need to replace acute toxicity tests on fish (LC50) with more co
st effective assays. The main objective of this study was to explore whethe
r gill epithelial cells, hepatocytes and Daphnia magna could be used to pre
dict acute toxicity of surfactants on fish. The acute toxicity of 10 synthe
tic surfactants (anionic, cationic, nonionic and zwitterionic) and two resi
n acids were determined on hepatocytes and gill epithelial cells from rainb
ow trout (Oncorhynchus mykiss), on Daphnia magna and on fish. Cell viabilit
y was measured with the fluorescent viability probe calcein-AM, immobilizat
ion was determined for Daphnia and 24-hr LC50 for rainbow trout. The EC50 v
alues for the cellular tests were clearly higher than the corresponding val
ues for Daphnia and fish, indicating that the cellular tests with the endpo
int used are less sensitive than whole organisms. A combination of the EC50
values for Daphnia and freshly isolated gill epithelial cells in suspensio
n showed, however, a good correlation with acute toxicity on fish (r(2) = 0
.91 and slope = 1.09, The combination seems to be a promising in vitro alte
rnative to acute toxicity tests on fish (LC50), but a more exhaustive compa
rison, including a broad spectrum of chemicals should be made before the pr
edictive value of the combined ir vitro test can be evaluated. (C) 2000 Els
evier Science Ltd. All rights reserved.