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(65-07) Simple recipe for calculating multi-substance toxic pressure as indicator of the ecological impact of toxic substances. van de Meent, Dik*,1, Struijs, Jaap1, Sijm, Dick2, 1 RIVM, Bilthoven, The Netherlands2 RIVM, Bilthoven, The Netherlands ABSTRACT- A simple log-linear equation has been found useful as a meta model for indicating effects of multi substance emissions on ecosystems. Starting from known production volumes of chemicals and estimated emission fractions, exposure concentrations in water and soil on regional, continental and global spatial scales were calculated by means of the nested multi-media mass balance model SimpleBox. Toxic pressures (PAF) were calculated from these exposure concentrations using species sensitivity distributions (SSD). Applying standard rules for combining single substance PAF into multi substance PAF, the total toxic pressures on ecosystems that results from exposure to multiple chemicals was calculated. Model calculations of this kind have been performed for a large number of chemical substances in the EINECS database. The results indicate that use and emission of these chemical at the present rates leads to substantial overall toxic pressures on aquatic and terrestrial ecosystems. In a further multivariate analysis of the calculation results, a log-linear regression equation was derived that related the model output (toxic pressures) directly to the model input (production volumes, emission factors, physical-chemical substance properties, degradation rate constants, SSD-parameters). The equation obtained explained a sufficiently large part of the variance in the model output to be useful as a meta model for calculating toxic pressure on ecosystems directly from substance properties and emission rates, bypassing the SimpleBox/SSD modeling procedure. We believe that this meta model can now serve as a basis for routine (re)calculation of overall toxic pressure from spatially and temporally varying sets of emissions, indicating trends in total ecological impact of toxic substances. This could serve as a monitoring instrument (indicator) of the effectivity of world-wide toxic substances policy. Key words: persistent organic pollutants, multimedia models, toxic pressure, ecological risk |
