Innovative exposure assessment in multimedia environments

Exposure Assessment

The established cell-based bioassays are invaluable for the hazard assessment and environmental monitoring of chemical mixtures but they require careful adaptation before they can be applied to environmental samples. Assay robustness and specificity in the presence of matrix components and other chemicals must be characterised and validated prior to their implementation within monitoring. Environmental samples contain not only the organic pollutants that are our target of interest, but also salts, metals and natural organic matter or lipids. Furthermore, samples usually need enrichment, in particular from pristine environments. Passive sampling methods offer useful and straightforward tools to enrich the chemicals of interest while largely leaving the matrix behind.

Comparing measured equilibrium partitioning concentrations in polymer-based passive samplers equilibrated with different media can serve as a proxy for differences in chemical activity between these media which can indicate e.g. the direction of diffusion. We use silicone polymers as the reference phase and employ them as “chemometers” that reflect these differences. As an example, we apply equilibrium-sampling techniques in samples from the aquatic environment as a novel, empirical and thermodynamically based approach to describe bioaccumulation. The approach provides novel insight into bioaccumulation and the partitioning properties of the major sorptive phases in biota, i.e., lipids, and in sediment, i.e., organic carbon. The “chemometer” approach has the potential to become a powerful tool to study the thermodynamic controls on the cycling and fate of persistent organic chemicals in the environment, and we work on extending it to other environmental compartments.