Environmental quality criteria for organic chemicals predicted from internal effect concentrations and a food web model

Abstract

Environmental quality criteria (EQC) for hydrophobic organic chemicals were calculated with a model for bioaccumulation in food webs. The model was calibrated and verified using polychlorinated biphenyl concentrations in food webs of shallow lakes. The EQCs in water and sediment were derived based on internal effect concentrations (IECs) for several modes of toxic action. By reverse calculation with the food web model for each organism in the web, a different water or sediment concentration is calculated corresponding to the IEC in each organism. A statistical procedure with an acute-to-chronic value is used to derive chronic EQCs based on bioaccumulation. The model-based chronic EQCs were compared with previously established EQCs. The EQCs calculated with the food web model generally are within an order of magnitude of the previously derived EQCs based on toxicity data on individual chemicals. Some previously derived EQCs are much lower than model predictions and usually based on small samples of toxicity data such as no-observed-effect concentrations (NOECs) with large assessment factors. When faced with data gaps, it is proposed to use model-based chronic EQCs for (polar) narcotic chemicals. Other modes of action require a different model concept to account for receptor-based toxicity.

Evaluation of Bioaccumulation Using In Vivo Laboratory and Field Studies

“…In addition, body burdens of specific chemicals in field‐collected organisms can be compared to known critical body residues derived from laboratory data, thus allowing prediction of risk of adverse effects. Traas et al (2004) coupled critical body residues to food web bioaccumulation models to develop environmental quality criteria that agree well, in most cases, with criteria based on data from toxicity testing. Thus, this method allows risk to be evaluated even when more traditional forms of bioaccumulation data for specific chemicals or components of the food web are lacking.…”

Transport, Accumulation and Transformation Processes

“…It is evident that with an increasing solidswater ratio and partition coefficient, the fraction of the chemical in the solid phase of the system also increases. For a chemical with a K p value of 10 5 L/kg, only some 10% would be associated with the particles (typically 78 Transport, accumulation and transformation processes 10 mg/L on a dry weight basis, FR w = small) in surface water. In a typical soil system where FR w = FR s = 40%, only as little as 10 -6 % of the same chemical would be present in the water phase.…”

“…The great advantage of these models is that food webs of any dimension can be described with as many food sources as required, and concentrations in all species can be calculated simultaneously [76]. In general, food web models successfully predict steady-state concentrations of persistent halogenated organic pollutants which are slowly metabolized [77,78]. However, these models are still relatively difficult to use for screening a large number of chemicals.…”

Critical Body Residues Linked to Octanol−Water Partitioning, Organism Composition, and LC50QSARs: Meta-analysis and Model

“…Variability is at least partly due to differences in the type of interval calculated (minimummaximum versus 90 percentile) and the substances and species included (4,5,69).…”