Use of bioassays to identify contaminants of emerging concern in the San Francisco Bay Delta

Title:	Use of bioassays to identify contaminants of emerging concern in the San Francisco Bay Delta
Category:	Oekotoxzentrum - Aktuelle Stunde
Date:	25. May 2012, 14:00 - 15:00
Venue:	Eawag Dübendorf
	Forum Chriesbach C24
Speaker:	Dr. Daniel Schlenk, Professor of Aquatic Ecotoxicology, University of California Riverside, USA
Leader:	Dr. Inge Werner, Oekotoxzentrum, Eawag/EPFL
Download:	as calendar event

Contaminants of Emerging Concern (CECs) represent a “universe” of known and unknown compounds including pharmaceutical and personal care products, nanomaterials, and human metabolites. Aquatic organisms tend to have the greatest exposure to human-derived CECs due to point source discharge of domestic wastewater effluents and to non-point source runoff to surface water. Significant uncertainty exists in determining the ecotoxicological risk of these compounds. Some studies have shown that exposure to relatively low concentrations of synthetic hormones have abolished populations of fish. Populations of threatened and endangered species of fish in the San Francisco Bay Delta have shown significant declines leading to changes in water allocations to the Central Valley and Southern California. Using an easily measured endocrine response (estrogenic activity), evaluations of surface waters that drain into the estuarary were carried out. Site-specific patterns of activity were observed with causal compounds varying between the Napa River and the Delta of the Sacramento River. Further analyses of the Sacramento River Delta have indicated the potential for pyrethroid insecticides, herbicides and surfactant mixtures as contributing factors to this response. Whether estrogenic activity is causally linked to population decline is uncertain. However, the temporal association between urban pyrethroid use and population declines in Delta fish species indicates further research is necessary.