The potential risk associated with the sediment-borne organic micropollutan
ts from the River Po (Italy) was evaluated using algal toxicity bioassays o
n Selenastrum capricornutum. Bed sediment samples were taken downstream fro
m the confluence of the main tributaries of the river during two sampling s
easons. A solvent extraction procedure of sediment fine fraction was used f
or both analytical and toxicological characterization. A good agreement was
found between toxicity data and levels of most analyzed contaminants, sugg
esting a combined action of the organic mixtures affecting the algal respon
ses. The ecotoxicological approach proved to be sensitive for the detection
of pollution sites along the river course.