Relative sensitivities among avian species to individual and mixtures of aryl hydrocarbon receptor–active compounds

Abstract

Dioxins and dioxin-like compounds (DLCs) are potent toxicants to most vertebrates. Sensitivities to DLCs vary among species. In the present study, the sensitivities of avian species (chicken [Gallus gallus], ring-necked pheasant [Phasianus colchicus], and Japanese quail [Coturnix japonica]) to some polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) were determined by using species-specific, in vitro, transactivation assays based on a luciferase reporter gene under control of species-specific aryl hydrocarbon receptors. In ring-necked pheasant and Japanese quail, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was not the most potent inducer of toxic effects. Especially for Japanese quail, the relative potency values of most of 9 PCDD/Fs tested were greater than for TCDD. The rank order of avian species sensitivities to DLCs was chicken > ring-necked pheasant > Japanese quail. Effects of binary mixtures of TCDD, 2,3,7,8-tetrachlorodibenzofuran, and 2,3,4,7,8-pentachlorodibenzofuran were strictly additive. Moreover, we also found that the primary DLCs that were responsible for most of the potency of the DLC mixtures can be deduced by using ordination in a multidimensional space defined by the avian species sensitivities. Overall, the relative potency and the species sensitivities of these chemicals could guide risk assessments to wild species when exposure to mixtures of DLCs in the environment.

Using In Vitro and Machine Learning Approaches to Determine Species-Specific Dioxin-like Potency and Congener-Specific Relative Sensitivity among Birds for Brominated Dioxin Analogues

“…Given that WHO−TEFs were derived primarily from chicken toxicity data, the avian species-specific ReP values of brominated dioxins derived in the present study were also compared with those of several PCDD/Fs and dl-PCBs derived from the same avian AHR1−LRG assays published previously. 59 Significant or apparent differences of species-specific ReP values existed between several PCDD/Fs, dl-PCBs, and their corresponding brominated analogues (Figure S5 and Tables S4 and S5), including 1,2,3,4,6,7,8-PXDD, 2,3,7,8-PXDF, 2,3,4,7,8-PXDF, PXB 77, and PXB 126. Some of the differences for ring-necked pheasant exposed to 1,2,3,4,6,7,8-PXDD, PXB 77, and PXB 126, and those for Japanese quail exposed to 1,2,3,4,6,7,8-PXDD, reached an order of magnitude.…”

Using In Vitro and Machine Learning Approaches to Determine Species-Specific Dioxin-like Potency and Congener-Specific Relative Sensitivity among Birds for Brominated Dioxin Analogues

“…Relative potency (ReP) of PBDD/Fs and dl-PBBs evaluated in the chicken, ring-necked pheasant and Japanese quail AHR1 constructs. 19 RePavg values for chlorinated congeners (RePCl) were calculated based on EC50-, PC10-, PC20-, PC50-and PC80 values from our previous avian AHR1-LRG assays, 20 which were listed in Table S5, unless otherwise indicated. RePavg values for brominated congeners (RePBr) were calculated from EC50-, PC10-, PC20-, PC50-and PC80-based ReP values listed in Table S3.…”

“…‡ It was the average of RePaverage value derived by Farmahin 21 and RePavg value listed in Table S5 For comparison among the avian WHO-TEFs and AHR1-LRG assays-derived ReP values for chlorinated and brominated congeners, the avian AHR1-LRG data for PCDD/Fs from our previous study 20 were reanalyzed following the same approaches as used in the present study. EC50, PC10, PC20, PC50 and PC80 values represent the average of three replicates ± standard error (SE) obtained from three 96-well plates for each compound.…”