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2B - Natural Stressors and Toxicants (TUP/67) Ohio 4: Eco-epidemiological validation of the concept of Species Sensitivity Distribution and mixture risk assessment. Posthuma, Leo1, de Zwart, Dick1, Dyer, Scott2, Hawkins, Charles3, 1 RIVM, Bilthoven, The Netherlands2 The Procter & Gamble Company, Cincinnati, Ohio3 Utah State University, Logan, Utah ABSTRACT- Ohio rivers have extensively been monitored for the occurrence of fish species in relation to habitat suitability and chemical exposure. By applying Species Sensitivity Distributions (SSD), availability assessment and mixture toxicity calculus, the toxic chemical exposure has been converted into a groupwise (industrial origin, household products and eventually pesticides) cumulative measure of toxic risk per sampling site. The calculated multiple substance Potentially Affected Fraction (msPAF) is considered to express toxic risk on a relative scale. The Ohio data have been used for eco-epidemiological modeling that quantifies the observed ecological effects on species composition and that attributes the effects to the probable underlying causes (see posters Ohio 1-3). Putting the focus on the modeled effects in relation to the risks calculated for the different groups of toxic compounds enables interpretation of the relative and dimensionless msPAF-scale in more absolute terms: "Loss of Species" and "Extra Species", for the sensitive and opportunistic species respectively. Key words: mixture toxicity, ssd, multiple stressors, eco-epidemiology |
