A novel passive dosing system for determining the toxicity of phenanthrene to early life stages of zebrafish.

Reliable experimental early life stage chronic toxicity data for fish are limited and further data are needed for polyaromatic hydrocarbons to establish environmental quality objectives and compare with toxicity model predictions. Efforts are underway to develop a zebrafish embryo toxicity test guideline to reduce, refine and replace the use of vertebrates in animal testing. An adaptation of this method which includes embryo lethal and sub-lethal developmental endpoints after a 5-day exposure as well as larval survival and growth endpoints during a subsequent 25-day test period is described using phenanthrene as a model test substance. To deliver well controlled exposure concentrations, a passive dosing system consisting of silicone coated vials and silicone O-rings was employed. Acute results indicated that edema and spinal curvature were the most sensitive sub-lethal effects observed and in many cases preceded observed mortality. The 30-day LC/EC10 for larval survival and growth was 40 and 67 μg/L respectively. Concentrations shown to cause adverse effects in this study are in the range of previous studies that have investigated the chronic effects of phenanthrene on fish. Further, results indicate that predicted water quality objectives for phenanthrene derived using the target lipid model are protective of early life stage effects on zebrafish. Based on these results the predicted water quality objectives for phenanthrene derived using the target lipid model (10 μg/L) would be protective of early life stage effects on zebrafish.