Seasonal variations of dioxine-like activity in sediments of the Bizerta lagoon (Tunisia) detected with in vitro cellular bioassays

Abstract : In order to evaluate sediment contamination in six stations from Bizerta lagoon, a combination of in vitro bioassays and chemical analysis was applied to sediment organic extracts. By using 7- ethoxyresorufin-O-deethylase (EROD) induction in the fish hepatoma cell line PLHC-1 after 4 h of cell exposure, dioxin-like activities were detected in all analysed samples. Dioxin-like activities were higher in winter than in summer. A highly significant correlation was observed between bioassay- and chemical analyses-derived toxic equivalents (TEQs), but PAHs accounted for only a small part of the detected biological activities. Our results suggest the presence of unknown readily metabolised EROD inducing compounds, which will need to be further characterized