Biological Evaluation of Pollution in the Sagami River Using the 7-Ethoxycoumarin O-Deethylase Activity Induced by River Sediment Extracts in HepG2 Cells

Abstract

The arylhydrocarbon receptor (AhR)-dependent induction of 7-ethoxycoumarin O-deethylase (ECOD) activity in HepG2 cells was employed in a longitudinal study of pollution in the Sagami River flowing into Sagami Bay using river sediment extracts. The six sampling points for river sediment were Ogurabashi, Shimomizo, Atsugi, Kurami, Shinomiya, and Hiratsuka (in descending order of distance from the estuary). In samples obtained at the four midpoints along the river, ECOD activity was induced almost to the same extent. Ogurabashi, the point farthest from the estuary, seemed less polluted than downstream areas based on ECOD activity, while a marginal increase in the activity above the baseline was found at the highest concentration in the sample from Hiratsuka. The points where the river sediment caused a marked induction of ECOD activity in HepG2 cells were surrounded by inland industrial areas scattered along the river.