Ecotoxicological assessment of bromobenzene using a test battery with five model systems

Bromobenzene (BrB) is used as a solvent for crystallization and as an additive to motor oils and may be released into the environment through various waste streams. However, there is limited available information about the toxic hazard of BrB in the aquatic environment. Consequently, the ecotoxicological effects induced by BrB were investigated using five model systems with representants from four trophic levels. The battery included bioluminescence inhibition of the bacterium Vibrio fischeri, growth inhibition of the alga Chlorella vulgaris and immobilization of the cladoceran Daphnia magna. Total protein content, neutral red uptake and MTS metabolization were reduced, while lysosomal function, succinate dehydrogenase activity, G6PDH activity and leakage, metallothionein levels and EROD activity were stimulated in PLHC-1 and RTG-2 fish cell lines. The most sensitive bioindicator was the bioluminiscence of V. fischeri, with an EC50 of 0.04 mM BrB at 15 min and a non-observed adverse effect level of 0.02 mM BrB. There is a large difference in sensitivity to BrB among the model systems probably due to the metabolic capacity of the different species. PLHC-1 cells were more sensitive to BrB than RTG-2 cells. The most prominent morphological effects observed were hydropic degeneration, loss of cells and of the perinuclear pattern of distribution of lysosomes. Therefore, BrB should be classified as toxic to aquatic organisms.