PARENT SESSION

PT07 Chemical and Biological Analysis of Endocrine Disrupting Compounds
Exhibit Hall
8:00 AM - Tuesday

(PT129) Characterization of dioxin-like and estrogenic activities in river sediments from Masan and Lake Shihwa, Korea using in vitro bioassay.

Yoo, H.¹, Khim, J.S.², Giesy, J.P.¹, ¹ Michigan State University, National Food Safety and Toxicology Center, East Lansing, MI, USA² Seoul National University, School of Earth and Environmental Sciences, Seoul, Korea

ABSTRACT- Extracts of river and creek sediments collected from inland areas of Masan Bay (n=15) and Lake Shihwa (n=21), were screened for their ability to induce aryl hydrocarbon receptor (AhR)- and estrogen receptor (ER)- mediated gene expression in vitro. Additionally, the cell viability test using molecular probes was conducted to determine an overall cytotoxicity of sediment extracts. Based on the screening of raw extracts, 34 of 36 sediment samples showed significant dioxin-like activity in the H4IIE-luc bioassay. The greatest magnitude of dioxin-like response observed was 130% of the maximum response elicited by a 1250 pM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) standard and about half of Lake Shihwa raw extracts exceeded 90%-TCDD-max. While, 27 sediment raw extracts out of 36 induced significant estrogenic responses in the MVLN bioassay, where the magnitudes of induction were usually less than 50% of the maximum response elicited by a 1000 pM 17-estradiol standard. Relative potencies (REPs) were, expressed as a range of values, calculated over multiple levels of response from 20-80%-standard-max. (REP_20-80-ranges) in order to account for potential uncertainty due to deviations from parallelism to the standard curve. The REP_20-80-ranges varied within a factor of two in the H4IIE-luc bioassay, where as the MVLN bioassay resulted in 100-fold variation in the REP_20-80-ranges. Thus, the evaluation of the dose-response relationships based on multiple point estimates showed that deviations from parallelism to the standard curve resulted in up to 100-fold uncertainty in point estimates of relative potency for the environmental samples examined. Some of raw extracts tested in the MVLN bioassay were cytotoxic. Overall, in vitro bioassay was a useful and rapid screening tool to characterize the causative agents and/or potential toxic compounds presented in river and creek sediments from Masan and Lake Shihwa areas

Key words: relative potency, sediment, in vitro bioassay