Cell bioassays for detection of aryl hydrocarbon (AhR) and estrogen receptor (ER) mediated activity in environmental samples

In vitro cell bioassays are useful techniques for the determination of rece ptor-mediated activities in environmental samples containing complex mixtur es of contaminants. The cell bioassays determine contamination by pollutant s that act through specific modes of action. This article presents strategi es for the evaluation of aryl hydrocarbon receptor (AhR)- (hereafter referr ed as dioxin-like) or estrogen receptor (ER)-mediated activities of potenti al endocrine disrupting compounds (EDCs) in complex environmental mixtures. Extracts from various types of environmental or food matrices can be teste d by this technique to evaluate their 2,3,7,8-tetrachlorodibenzo-p-dioxin e quivalents (TCDD-EQs) or estrogenic equivalents (E-2-EQs) and to identify c ontaminated samples that need further investigation using resource-intensiv e instrumental analyses. Fractionation of sample extracts exhibiting signif icant activities, and subsequent reanalysis with the bioassays can identify important classes of contaminants that are responsible for the observed ac tivity. Effect-directed chemical analysis is performed only for the active fractions to determine the responsible compounds. Mass-balance estimates of all major compounds contributing to the observed effects can be calculated to determine if all of the activity has been identified, and to assess the potential for interactions such as synergism or antagonism among contamina nts present in the complex mixtures. The bioassay approach is an efficient (fast and cost effective) screening system to identify the samples of inter est and to provide basic information for further analysis and risk evaluati on.