MEPS 274:1-16 (2004)  -  doi:10.3354/meps274001

Protein model for pollutant uptake and elimination by living organisms and its implications for ecotoxicology

Susan Quinnell1,*, Kees Hulsman1, Peter J. F. Davie2

1Australian School of Environmental Studies, Nathan Campus, Griffith University, Queensland 4111, Australia
2Biodiversity Program, Queensland Museum, GPO Box 3300, South Brisbane, Queensland 4101, Australia

ABSTRACT: The conceptual model on which chemical assessment of pollutants is based is flawed. The assumption in ecotoxicology ‹ that pollutants cross the biological membrane only by passive diffusion of their solute phase (diffusion model) and thus, that only water-soluble pollutants are biologically available ‹ is inconsistent with the biologists¹ understanding of the role and functioning of the biological membrane. The biological membrane both isolates organisms, cells and organelles from their external environments and regulates cross-membrane trafficking of polar and non-polar substances. Trafficking regulation is a function of proteins dissolved within the membrane. An alternative protein model for pollutant uptake and elimination is proposed that provides a credible explanation of how solid-phase pollutants, such as those bound to aquatic sediments and soils, may be readily incorporated by living organisms. Current chemical testing is likely to underestimate the risk posed to organisms by sediment and soil-bound pollutants. New techniques for assessing the bioavailability and impacts of pollutants, based on the protein model, are urgently needed.

KEY WORDS: Ecotoxicology · Pollution · Protein model · Diffusion model · 3-phase model · Cell membrane · Equilibrium partitioning coefficient · Transport proteins · Sediment · Pore water

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