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(388) Is Food-borne Cadmium more Bioavailable than Sorbed/water-borne Cadmium? Metzler, David1, Kim, Sang2, Cha, Daniel1, Allen, Herbert1, 1 2 ABSTRACT- Freshwater algae are normally provided as the primary source of food during Ceriodaphina dubia toxicity tests. A large body of environmental literature demonstrates that algae are capable of accumulating heavy metals. Consequently, questions regarding whether or not the toxic metals incorporated in food particles (i.e. algae) influence laboratory-based toxicity tests must be addressed for a better understanding of variation that occurs in such tests and for improving the standardization of test procedures. The objective of this study was to investigate the effect of feeing Cd-laden algae on 7-day chronic toxicity tests. Including Cd to the feed of a chemostat culture of Selenastrum capricornutum provided a continuous supply of Cd-laden algae. The ability of algae to mediate Cd toxicity by making it more or less bioavailable was then determined by continuously delivering the chemostat effluent to a flow-through bioassay system containing Ceriodaphina dubia. A control system that introduced the same level of Cd prior to the bioassay chamber (after chemostat) was operated in parallel to assess the toxic effects resulting from a similar level of exposure to non-algal-incorporated Cd. The above bioassay was performed at 6 different concentrations of Cd for each algal regime. These results were used to compare the NOEL and LOEL values for the two different routes of Cd exposure. Key words: Bioassay, Ceriodaphina dubia, Bioavailability, Cadmium |
