Title: Bioanalytical approaches for the detection of dioxin and related halogenated aromatic hydrocarbons

Auteur(s): Denison MS ; Nagy SR ; Clark GC ; Chu M ; brown DJ ; Murata H ; Shan G ; Sanborn JR ; Hammock BD ;  ; 

Year: 2001

Journal: Organohalogen Compounds

Subject(s): dioxin ; polychlorinated ; polychlorinated dibenzo-p-dioxins ; PCBs ; PCB ; toxicity ; food ; identification ; extraction ; screening bioassay ; bioassay ; TCDD ; Ah receptor ; Luciferase ; Reporter gene ; gene expression ;  ; 

Summary: Halogenated aromatic hydrocarbons (HAHs), such as polychlorinated dibenzo-p-dioxins (PCDDs), biphenyls (PCBs) and dibenzofurans (PCDFs), represent a large group of compounds which because of their ubiquitous distribution, resistance to biological 'and chemical degradation, high toxicity and potential for bioaccumulation/biomagnification, can have a significant impact on the health and well being of human and animals. HAHs have been identified worldwide in a variety of wildlife, domestic and human tissues as weil as in food. water, and soil samples. Given these issues. the detection and quantitation of these chemicals in biological. environmental and food samples is of paramount importance. Since HAHs are found not as individual congeners, but as complex HAH mixtures, one problem in the evaluation of risk to HAHs is the identification and quantitation of the toxic/bioactive HAH congeners in a given sample. Although chemical extraction procedures coup led with high resolution gas chromatography-mass spectrometry (HRGCIMS) is considered the gold standard for the identification and quantitation of individual PCDD, PCB and PCDF congeners, these procedures are very costly and time-consuming. Accordingly, a variety of rapid and inexpensive screening bioassays capable of detecting and estimating tbe relative potency of complex mixtures of HAHs have been developed by our lab and others. These bioanalytical methods are based on the ability of the compounds to be specifically recognized and bound by antibodies (immunoassays) or their ability to transduce a specific biological response in vitro or in cells in culture (bioassays). Current bioassays are based on the mechanism of act ion of TCDD and relaled HAHs and utilize the Ah receptor (AhR), a ligand-dependent factor which mediates both tbe effects of these chemicals. One major HAH bioassay (Chemically Activated Luciferase Expression (CALUX» utilizes a cell line that contains a stably integrated AhR-responsive luciferase reporter gene and this system takes advantage of the ability of the AhR to activate gene expression in a ligand-dependent manner. Exposure of these cells to extracts containing TCDD and/or related HAHs results in the induction of luciferase gene expression in a time-, dose- and chemical specific manner. The second is an in vitro assay which measures the ability of a chemical (ligand/agonist) to bind to the AhR and stimulate its transformation and DNA .binding. Both assays are quantitative in that the responses are proportional to the amount of AhR agonist (TCDD/HAH) in the test sample. Although these bioanalytical methods can detect HAHs and related chemicals, each has advantages and disadvantages.