SREL Reprint #1862





Synopsis of Discussion Session on the Bioavailability of Inorganic Contaminants

William H. Benson (Chair), James J. Alberts, Herbert E. Allen, Carlton D. Hunt, and Michael C. Newman


Bioavailability is a widely accepted concept based on the implicit knowledge that before an organism may accumulate or show a biological response to a chemical, that element or compound must be available to the organism. While the concept of bioavailability is widely accepted, the processes that control it are poorly understood. This latter situation results from an incomplete understanding of basic processes in aquatic systems, which is further exacerbated by the numerous and sometimes conflicting qualitative definitions of bioavailability used by investigators from different scientific disciplines.

Bioavailability is defined here as the degree to which a chemical is able to move into or onto an organism. This definition is given here only to provide a framework in which to discuss limitations in the understanding of bioavailability as it pertains to inorganic species in aquatic systems-not because we feel that this should be the only definition. We focus on the bulk chemistry of the aquatic phase as it affects speciation and, presumably, availability of inorganic contaminants. It is assumed that transfer mechanisms operate within the diffusion layer existing between the bulk phase and membrane(s) to move the chemical into the organism. We further assume that transfer must occur within the solution phase regardless of the membrane type or location within the organism (e.g., gill, gut, or dermis). Thus, inorganic species in phases that are not dissolved within the bulk solution must involve dissolution for the chemical to become bioavailable.

SREL Reprint #1862

Benson, W.H., J.J. Alberts, H.E. Allen, C.D. Hunt, and M.C. Newman. 1994. Synopsis of discussion session on the bioavailability of inorganic contaminants. p. 63-71. In Bioavailability: Physical, Chemical and Biological Interactions, edited by J.L. Hamelink, P.F. Landrum, H.L. Bergman, and W.H. Benson. Lewis Publishers. Proceedings of the Thirteenth Pellston Workshop, Pellston, MI.

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