The teratogenicity and cardiotoxicity of phenanthrene in zebrafish, Danio rerio

Phenanthrene, classified as a tricyclic polycyclic aromatic hydrocarbon (PAH) and listed as a priority pollutant by the US Environmental Protection Agency, poses a potential hazard to fish. This study evaluated the effects of phenanthrene on the early development of zebrafish (Danio rerio) using an innovative passive dosing system. This system maintained consistent concentrations of phenanthrene below water solubility limits through a 5-d acute exposure period, allowing for an accurate assessment of its potential lethal, teratogenic, and cardiotoxic effects. Concentrations up to solubility limits did not result in sufficient mortality to calculate LC50 values, however, the derived 5-d LOEC (lowest-observed-effect concentration) and NOEC (no-observed-effect concentration) values for mortality were 110 and 50 μg/L, respectively. Following exposure, the maximal prevalence of teratogenic effects observed above the controls was 17 % pericardial edema, 15 % yolk edema, 18 % tail kinking and 15 % delayed hatching. Edemas showed evidence of reversibility. The cardiotoxic effects of phenanthrene in isolated adult zebrafish hearts exposed in situ (< 2 h) were examined using an optical mapping technique. Phenanthrene (110 μg/L) induced significant tachycardia (170 % ± 19.3 compared to control), shorter action potential durations (73.7 % ± 19.1) and calcium transient durations (89.2 % ± 30.0). A drug washout effect showed potential reversibility for the effects on heart rate, action potential, and calcium transient. The identified lethal, teratogenic, and cardiotoxic impacts arising from exposures to environmentally relevant concentrations of phenanthrene indicate possible implications for the overall survival and fitness of fish in phenanthrene contaminated environments.