Effects of an environmentally relevant polychlorinated biphenyl (PCB) mixture on embryonic survival and cardiac development in the domestic chicken
A 58‐congener polychlorinated biphenyl (PCB) mixture based on contaminant analysis of spotted sandpiper eggs collected along the Upper Hudson River, New York in 2004 was used to study in ovo PCB effects on cardiac development in the domestic chicken. Fertile eggs were injected prior to incubation with the following doses of the PCB mixture: untreated, sham, 0.0, 0.03, 0.08, 0.30, 0.50, 0.70, and 2.06 µg PCBs/g egg wt (TEQ range of 0.004‐0.266 ng/g). In addition, there were untreated and sham‐control groups. Embryonic development was monitored throughout incubation and chicks were necropsied at hatch. Hatchability followed a dose‐dependent curve with significant (p<0.05) mortality above the 0.50 µg PCBs/g egg wt treatment compared to controls. The LD50 of this PCB mixture in hatchling chicks was estimated as 0.40 µg/g egg wt (0.052 ng TEQ/g egg weight) based on the lethality curve. Cardiac arrhythmia was observed at embryonic day (ED) 14 of development in embryos treated at concentrations of 0.50 µg/g egg wt and above. Histological analysis was utilized to characterize any cardiac abnormalities. Cardiomyopathies increased across treatments in a dose‐dependent manner compared to control groups. Identified abnormalities included the absence of the trabeculated layer of the ventricular wall, ventricular dilation, thinning of the ventricular walls, malformation of the septal wall, and most commonly, absence of the compact layer of the ventricular wall. Chick heart width, depth, total area, compact layer depth, septal width, chamber area, and ventricular wall dimensions did not differ across treatments. This study supports prior reports of adverse developmental effects of PCBs on cardiovascular systems in birds. Although the eggs hatched, the measured cardiomyopathies suggest potential deleterious long‐term impacts on individual health and fitness. Environ. Toxicol. Chem. © 2013 SETAC
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