M7 AM Metals in the Environment: Chemistry and Fate Issues
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 327-329

(WOO-1117-675119) How hard is that diet? Implications for metal accumulation and toxicity.

Wood, C¹, Franklin, N¹, Alves, L.¹, Ojo, A.¹, Niyogi, S.¹, Kamunde, C.¹, Pyle, G.¹, Chowdhury, J.¹, Kjoss, V.¹, Nadella, S.¹, ¹ McMaster University, Hamilton, Ontario, Canada

ABSTRACT- The importance of the hardness of the exposure water in reducing the uptake and toxicity of waterborne metals is well-established. However, the importance of dietary hardness has been largely overlooked. This presentation will synthesize recent evidence indicating that relatively small elevations (2- 3 fold) in the calcium content of the diet (added as CaCO3) can offer a major protective impact against the uptake and toxicity of both waterborne and dietary metals to freshwater rainbow trout. To date, protective effects have been documented against cadmium, zinc, and lead, all of which can behave as calcium analogues. Analogous protective effects of elevated dietary sodium (added as NaCl) may occur for metals such as copper which are sodium analogues. The mechanistic nature of this protection will be explored, with an emphasis on the sites and mechanisms of action in the digestive tract and gills.(Supported by NSERC, MITE-RN, ICA, CDA, NiPERA, ILZRO, Teck-Cominco, Noranda-Falconbridge, & Inco).

Key words: diet, calcium, cadmium, zinc