Correlations between the RTG-2 cytotoxicity test EC50 and in vivo LC50 rainbow trout bioassay

This paper presents data on the validation of the RTG-2 in vitro cytotoxicity test. Correlations between in vivo 96h LC50s on rainbow trout and in vitro EC50s obtained with this test, were established. The acute cytotoxicity of 16 common aquatic pollutants were determined in vitro on RTG-2 cells, an established fibroblastic-like cell line derived from rainbow trout, using three quantitative analyses, as toxicological endpoints, on the same cell microplate: intracellular ATP content; cellular viability using neutral red assay (NR), and detachment of the grown surface substratum using FRAME KB protein assay (KBP). The three values obtained, were also transformed by a cytotoxicity index (CI), in a singular value of cytotoxicity. Dose-response curves were obtained. Good correlations between in vivo LC50s and in vitro EC50s for each endpoint and for the cytotoxicity index (CI) were found. Correlation coefficients were 0.965, 0.968, 0.977 and 0.970 for ATP, NR, KBP and CI50 respectively. Results indicate the applicability of the RTG-2 test as alternative protocol to estimate the acute toxicity of chemicals on fish without using live animals. The inclusion of this test instead of standard toxicity tests on fish would provide a fully alternative system, without testing on vertebrate animals, for the classification and preliminary risk assessment of the environmental hazard of substances.