Evidence of genotoxicity related to high PAH content of sediments in the upper part of the Seine estuary (Normandy, France).

In order to characterize the genotoxicity in the Seine estuary and Seine bay, chemical and toxicological analyses were performed on 17 sediments collected in June 2001 and June 2003. Many potent mutagenic and/or carcinogenic compounds - including polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and metals - were detected. Those compounds were found to be at relatively high concentrations in the upper part of the Seine estuary but were barely detectable at sites outside the plume from the Seine. The levels of pollution did not vary significantly between the two sampling periods, except that PAH concentrations in sediments collected at Oissel and Le Havre showed a marked increase in June 2003. The toxicity of organic extracts from sediments was evaluated by both embryotoxicity and in vitro genotoxicity (SOS Chromotest) assays. Organic extracts from sediments taken from the Seine estuary appeared significantly more embryotoxic than those from the Seine bay. In addition, the sediment extracts from the upper part of the Seine estuary exhibited higher genotoxicity than those from the lower part, and no genotoxicity was reported for sediments from the Seine bay. The genotoxic activity was detected only after adding an S9 microsomal fraction, suggesting the preponderant involvement of pro-genotoxic organic compounds. In addition, SOS Chromotest responses obtained with purified organic fractions revealed that PAH and, to a lesser extent, unknown polar organic compounds were probably responsible for this genotoxicity. Altogether, these results suggest that sediments from the upper Seine estuary are genotoxic and embryotoxic, and therefore, could be potentially hazardous for species living or feeding in the area.