In vitro cytotoxicity assessment of the biocidal agents sodium o-phenylphenol, sodium o-benzyl-p-chlorophenol, and sodium p-tertiary amylphenol using established fish cell lines

The cytotoxicity of three biocidal agents frequently employed as active ingredients in phenolic-based disinfectants, were evaluated in three established fish cell lines (EPC, CHSE and RTG-2). Cell viability was assessed using two fluorescent indicator dyes, Alamar Blue™ for metabolism and neutral red for lysosomal activity. Total protein content was also quantified as a measure of cell detachment. In order to evaluate the sensitivity of the cell cultures, the results obtained were compared with toxicity data obtained from a previous study with the same three compounds and the in vivo lethality test with rainbow trout. Results from this study established that each of the three cell lines ranked the tested chemicals in the same order of toxicity as the in vivo test; however, the cell cultures were found to be an order of magnitude less sensitive than whole fish studies with the same compounds. The chemical sodium o-benzyl-p-chlorophenol was consistently ranked the most toxic of the tested compounds with each cell line and the endpoints employed. The rank order of toxicity was always sodium o-benzyl-p-chlorophenol > sodium p-tertiary amylphenol > sodium o-phenylphenol. The EPC cells were found to be the most sensitive cell line tested based on Alamar Blue™ IC₅₀ data, and the Alamar Blue™ assay was consistently found to be the most sensitive endpoint of the three cytotoxicity assays employed.