CHARACTERIZATION OF THE H4IIE RAT HEPATOMA-CELL BIOASSAY AS A TOOL FOR ASSESSING TOXIC POTENCY OF PLANAR HALOGENATED HYDROCARBONS IN ENVIRONMENTAL-SAMPLES

An in vitro system, the H4IIE rat hepatoma cell bioassay, was characterized for use in assessing the overall toxic potency of PCBs, PCDDs, and PCDFs in extracts from environmental samples. This in vitro bioassay of cytochrome P450IA1 catalytic activity in the H4IIE cells in response to planar halogenated hydrocarbons (PHHs) was repeatable over time and standards were reproducible among laboratories when dosing conditions were similar. Three common extraction/cleanup procedures tested had no adverse affect on the response of the cells and biogenic interferences were not encountered. Comparison of the response of the H4IIE cells to extracts was calibrated against their response to the standard, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). This method of calibration proved to be effective for quantitation of known amounts of PHHs spiked into a sample matrix. The potential utility of this bioassay is as an integrative tool to assess the toxic potency of complex mixtures of PHHs. The results of this bioassay can complement chemical residue analysis and direct the need for such analysis, as well as aid in the interpretation of biological effects data from environmental studies.