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(P524) Teleost embryotoxicity testing of alkyl-phenanthrenes with a partition controlled delivery exposure protocol.
Kiparissis, Yiannis*,1, Akhtar, Parveen1, Alexander, Alexa1, Turcotte, Dominique1, Hodson, Peter1, Brown, Stephen1, 1 Queen's University, Kingston, ON, Canada
ABSTRACT- There are considerable uncertainties in risk assessments and water quality criteria for hydrophobic compounds when based on conventional static exposure toxicity tests. Due to adsorption and volatization, estimated toxic concentrations often exceed solubility limits because excess chemical must be added to achieve an adequate exposure. To overcome these uncertainties, we developed a reliable, partition controlled delivery (PCD) protocol to deliver and maintain constant concentrations of hydrophobic compounds in test solutions at or below their solubility limits over extended periods. Polydimethylsiloxane (PDMS) films containing various concentrations of C1-C4 phenanthrenes were deposited on the side of 20 mL vials and equilibrated with 10 mL of test media for 24 h. Fertilized Japanese medaka (Oryzias latipes) eggs were added for a 17-day embryotoxicity test at 25oC. Results from parallel 24h-static renewal assays demonstrated that the prevalence of blue-sac disease (BSD) symptoms in larvae increased in an exposure-dependent manner in both test regimes. In the static-renewal assays, only one compound caused toxicity below its water solubility limit, and EC50s of the other three compounds exceeded their solubility limits by 5 to 50 times. In contrast, all EC50s in the PCD assay were within the water solubility limits, indicating that this is a more realistic protocol for assessing the embryotoxicity of non-polar compounds.
Key words: embryotoxicity, new methods, alkyl-PAHs, Japanese medaka
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