Determination of dioxins in environmental samples: Comparison of biological and chemical-analytical results

Toxic equivalents (TE) of dioxins, furans and related compounds can be determined directly by measuring the aryl hydrocarbon hydroxylase activity (AHH-assay) in rat hepatoma cells. This method has major advantages over the classical chemical-analytical approach, if TEs in complex environmental samples are to be determined with little expense in terms of work and time. The specific bioassay covers all compounds with dioxin-like effects. These include over 5000 possible mixed halogenated dioxins and furans (PXDD/F) and in addition mixed halogenated biphenyls (PXB). Statutory regulations stipulate that only 17 selected chlorinated dioxins and furans (PCDD/F) have to be determined by chemical-analytical means [3]. Previous results show [1, 2], that the biologically determined TEs are higher than TEs calculated from chemical-analytical data. Exact reasons for this are unknown. The AHH-assay allows inexpensive screening for TEs in environmental samples. Our results indicate that there are compounds with dioxin-like effects, which are unknown or have not yet been recorded by chemical analysis.