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Extracts of mollusks collected from eight cities along the coast of the Bohai Sea, China, were used to determine dioxinlike activity using an in vitro bioassay approach. Dioxinlike activity of total extracts was detected by measuring luciferase activity in a stable transfected rat hepatoma cell line, H4IIE, containing an aryl hydrocarbon receptor (AhR)-responsive element linked to a luciferase reporter gene. Luciferase activity was expressed as a percentage of the maximum response observed for 2,3,7,8-TCDD (% TCDD(max)). All mollusk samples elicited significant dioxinlike activity except those from Dalian (N1). The greatest magnitudes (+/-SD, data ex N1) of activity observed for these extracts ranged from 4.88+/-0.48% to 11.38+/-1.43% TCDD(max). The mean activity was 7.37+/-1.85% TCDD(max). Concentrations of TCDD-EQs in mollusk extracts were from 227.4 to 547.5 pg g(-1) lipid. The cytotoxic effect of the mollusk extracts on cells was assessed at the same time. Six of the mollusk extracts (N2, N3, N4, S1, S2, and S4) caused noticeable growth inhibition over the exposure period at concentrations higher than 0.33% of the extracts concentrations (0.83 microL extract well(-1)). All the dilutions of sample N1 were cytotoxic to the H4IIE cells.

Sediments from two rivers in China, the Haihe and Dagu Rivers, were examined for estrogenic activity using an estrogen receptor (ER)-mediated in vitro bioassay system. ER-active compounds were isolated from sediments by Soxhlet extraction, and the crude extracts were fractionated using a florisil column into three fractions. The estrogenic activity of each extract was detected by measuring luciferase activity in the human breast cancer cell line MCF-7 transfected with a luciferase receptor gene. Significant estrogenic activity was observed in each total extract. The 17beta-estradiol equivalents (E2-EQs) ranged from 8.24 to 95.28 ng E2 g(-1) dw. As a result, the relative estrogenic potencies of three fractions in this study descended in the order of Fraction 3>Fraction 2>Fraction 1. The results of the bioassay analysis indicated the heavy pollution status of these sites with estrogenic contaminants. In this study, five selected chemicals, the natural estrogens 17beta-estradiol (E2) and estrone (E1), and the xeno-estrogens 4-octylphenol (OP), 4-nonylphenol (NP), and Bisphenol A (BPA) were also analyzed using the in vitro bioassay. The estrogenic activity of these chemicals were E2>E1>NP>OP>BPA.