Toxicity of retene to early life stages of two freshwater fish species

Larval zebrafish (Danio rerio) were exposed for 14 d to graded nominal conc entrations of waterborne retene (7-isopropyl-1-methylphenanthrene) from 5 t o 336 h postfertilization. Reduced growth, yolk sac edema, and mortality we re observed before swim up at nominal concentrations of 320 mu g/L and high er in a concentration-dependent manner. Similarly, exposures of rainbow tro ut (Oncorhynchus mykiss) to retene (32-320 mu g/L) for 42 d from the eyed e gg stage to hatch and from hatch to the onset of swim up behavior caused ex posure-related increases in blue sac disease posthatch. Symptoms included i ncreased activity of cytochrome P4501A (CYP1A) enzymes, yolk sac edema, sub cutaneous hemorrhaging, reduced growth, and craniofacial malformations. Chr onic exposure to retene resulted in mortality before swim up. Blue sac symp toms were observed in fish exposed to nominal concentrations as low as 32 m u g/L, the lowest concentration tested, and fin erosion and opercular sloug hing were evident in 100% of retene-exposed swim up larvae. No symptoms wer e observed in control fish or in fish exposed to acetone, the solvent carri er. The observed pathology resembles the toxicity of 2,3,7,8-tetrachlorodib enzo-p-dioxin toxicity to developing stages of fish, and our results sugges t that chronic exposure to polycyclic aromatic hydrocarbons may be responsi ble for recruitment failure associated with pulp mill effluents and oil spi lls.