PARENT SESSION

(560) Evaluation of marine sediments from the Southern California bight for estrogenic activity using in vitro and in vivo assays.

Hwang, W¹, Sapozhnikova, Y¹, Kelly, M², Montagne, D³, Armstrong, J⁴, Schlenk, D¹, ¹ Environmental Toxicology Program, University of California, Riverside, CA, USA² City of San Diego, Metropolitan Wastewater Department, San Diego, CA, USA³ Los Angeles County Sanitation District, Whittier, CA, USA⁴ Orange County Sanitation District, Fountain Valley, CA, USA

ABSTRACT- The exposure and uptake of environmental estrogenic compounds have been reported in previous studies of demersal flatfish species in the Central Southern California Bight (SCB). The objective of this study was to evaluate the estrogenic activity of the marine sediments from the SCB by using in vitro and in vivo assays. Sediment extracts were collected at the wastewater outfall regions of LA County (LAC), Orange County (OC) and San Diego County (SDC). The in vitro estrogenic activity of each extract was evaluated by the yeast estrogenic screen (YES) assay. Estrogenic YES activity from sediment ranged from 0.1-1 ng/g 17-estradiol (E2) equivalents. Cultured male California Halibut (Paralichtys californicus) were used to determine the biological response to xenoestrogen exposure by measuring the level of serum vitellogenin. Three laboratory exposure experiments were conducted: (1) sediment-only, (2) single injection of sediment extract and (3) 2-injections of extract over 7 days. There was a significant elevation of vitellogenin in adult male CH following a 7 day exposure to sediments. Single injection experiments failed to significantly induce vitellogenin. In contrast, approximately 1-90 g/kg E2 equivalent was observed in CH when sediment extracts from the 3 outfalls were injected twice over 7 days. The E2 equivalent of the LAC sediment extract was 6.6-fold higher than the SDC, and 70.7-fold higher than the OC outfall extract. These results reveal that a 7-day sediment-only exposure was sufficient to induce estrogenic activity in male CH. Moreover, other exposure routes, such as dietary routes, may also contribute to estrogenic activity observed in flatfish collected in the SCB (Supported by Coastal Environmental Quality Initiative, UC-Marine Council).

Key words: yeast estrogenic screen assay, demersal flatfish, estradiol, vitellogenin