The use of cell cultures as an alternative to live animals in acute fish toxicity testing

The toxicity of various chemicals was investigated in vitro and in vivo in carp ('Cyprinus carpio') and tilapia ('Oreochromis spilurus'). In order to study tilapia in vitro it was necessary to establish and characterise a cell line. A fibroblastic cell line, called TSB cells was derived tilapia brain. A cytotoxicity assay was devised utilising cultures of EPC cells (of carp epithelioma origin) and TSB cells. The effects of the test chemicals were assessed quantitatively by protein assay or lysosomal uptake of Neutral Red dye, and subjectively by light microscopy. The in vivo toxicities of the same chemicals were studied in static 96h LC[sub]50 bioassays. The responses by carp and tilapia to the effects of the chemicals were recorded. In addition, histopathological examination was carried out on a number of tissues of fish employed in the LC[sub]50 tests. From these examinations, further information as to the nature of toxicity caused by each chemical in carp and tilapia was produced. Correlations between in vitro and in vivo acute toxicities were generally good, although the in vitro assays lacked comparable sensitivity. It is therefore not possible at this stage to adequately replace live animals with cell cultures in toxicity testing. However, the results obtained here clearly establish that the use of cell cultures in toxicity assessment programmes could lead to a reduction in the numbers of fish being used. This investigation has also clearly identified the avenues future research has to explore if the use of live fish is to be minimised.