Effects of Dietary Metal/Metalloid Exposure on Aquatic Organisms
Conventional wisdom in aquatic toxicology has been that water is the primary exposure route determining the toxicity of most metals and metalloids (e.g., Cu, Zn, Ni, Cd, Pb, As) to fish and other aquatic organisms. Relative to water exposure, toxicity from contaminated diets did not appear to be a significant pathway in determining toxicity, with the exception of mercury and selenium. Thus, environmental criteria and other risk assessments for these toxicants have focused on waterborne toxicity.
However, some research efforts have indicated that dietary exposure can be important for some metal/metalloids, species, and exposure conditions, but this issue is mired in conflicting and insufficient data. To determine if and how dietary exposure should be considered in metal/metalloid risk assessments, MED is both reviewing past research and conducting new studies on metal/metalloid dietary toxicity.Particular emphasis is being given to contaminated diets similar to what would occur in natural systems; to that end, toxicity to fish is being assessed using a diet of live aquatic worms that have been exposed to contaminated sediment and/or water. The effects of copper, zinc, lead, cadmium, and arsenic on the growth of fish have been investigated, which identified dietary arsenic as being of particular concern for certain mining-contaminated sites. Current work is characterizing the arsenic contamination at such sites, relating dietary toxicity to fish to different arsenic forms, addressing mechanisms by which this toxicity occurs, and establishing the combined effects of waterborne and dietary exposure. Future work will expand efforts to other aquatic species and toxicants.
Erickson, R.J., J.D. Fernandez, T.L. Highland, J.R. Hockett, D.J. Hoff, C.T. Jenson, and D.R. Mount. Arsenic toxicity to juvenile fish: Effects of exposure route, arsenic speciation, and fish species. SETAC, Boston, MA, November 13-17, 2011.
Hoff, D.J., T.L. Highland, J.R. Hockett, C.T. Jenson, and M. Poe. Dietary arsenic toxicity in subadult rainbow trout: Growth effects, nutrient absorption, and tissue bioaccumulation. SETAC, Boston, MA, November 13-17, 2011.
Erickson, R.J., D.R. Mount, T.L. Highland, J.R. Hockett, and C.T. Jenson. 2011. The relative importance of waterborne and dietborne arsenic exposure on survival and growth of juvenile rainbow trout. Aquatic Toxicology 104:108-115.
Erickson, R.J. and D.R. Mount. 2011. Dietborne metals exposure issues for USEPA aquatic life criteria. Report to USEPA Office of Water.
|J. Russell Hockett|
Research project update date
June 22, 2011