[Comparison of the methods for assessing Ah effects in aquatic system by semipermeable membrane device and caged...

Semipermeable membrane devices (SPMDs) in combination with in vitro ethoxyresorufin-O-deethylase (EROD) assay was used to assess the aryl hydrocarbon receptor (AhR) effects in aquatic system. In present work, polycyclic aromatic hydrocarbons (PAHs) were selected as target compounds and SPMDs were deployed simultaneously with caged crucian carp for 32 days at five sites in Meiliang Bay, Taihu Lake. The concentrations of PAHs in the SPMD dialysates and fish tissues were analyzed by gas chromatography-mass spectrometry. In addition, the EROD activity of SPMD dialysates was assayed with H4IIE rat hepatoma cells and the induction of EROD activity in pancreas and liver of fish was also assayed. It was found that dialysates from SPMDs with longer exposures generally induced stronger activity and the toxic potency of dialysates expressed as bioassay-derived 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents ranged from 3.8 pg/g to 6.2 pg/g for 32 days exposure. A correlation of toxicity equivalency quantity (TEQ) with chemical analysis and in vitro bioassay-derived TEQ(bio) of SPMD dialysates yielded an R2 of 0.88, therefore, indicated that PAHs were one of the important AhR agonists in the water. Empirical evidence suggests that PAHs can account for about 40% to 50% of the potency observed. Moreover, a good correlation was observed between the results of EROD bioassay in vivo and EROD bioassay in vitro (R2 = 0.62), thus reflected that these two methods can be complementarily each other. It is, therefore, suggested that the SPMD technique combined with chemical analyses and in vitro EROD assay might be a valuable monitoring tool to assess the levels and effects of AhR agonists in water ecosystem.