Polychlorinated biphenyl exposure and impacts on reproduction and health parameters that affect mortality risk in bottlenose dolphins
Year: 2026
Type: article
Abstract: Polychlorinated biphenyls (PCBs) are legacy pollutants associated with numerous adverse health effects. We synthesized PCB and health data collected over multiple decades and across six bottlenose dolphin ( Tursiops spp.) populations, including a population near the heavily PCB-contaminated LCP Chemicals Site in Brunswick, Georgia, US. We used samples from males and juvenile females (n=396) to compare PCBs across populations, explore fine-scale spatial trends near the LCP Chemicals Site, and examine temporal trends for bottlenose dolphins sampled near Brunswick, and near Charleston, South Carolina. As females depurate a large portion of their PCB burden to their offspring, we also used the full sample set (n=580) to examine timing of decrease in blubber PCB burden in females as an indicator of first successful reproduction. Finally, we investigated associations of PCB concentrations with health indicators and thyroid hormones. We found that, although PCBs declined over time (3.54% and 5.01% decline per year for Brunswick and Charleston, respectively), concentrations are still extremely high in dolphins sampled near the LCP Chemicals Site. Geometric mean total PCBs combined over years for the Brunswick population was 236 (95% CI:198–280) μg/g lipid, but ranged from only 46 to 60 μg/g lipid for populations outside southern Georgia. At Brunswick, concentrations of summed congeners of Aroclor 1268, the commercial PCB mixture associated with LCP Chemicals Site operations but rarely used elsewhere, decreased with increasing sampling distance from the site. The median age for females classified to the sample group that had presumably successfully reproduced, indicated by decreased PCB concentration, was 20.4 years for Brunswick, compared with 11.6 years for other populations, suggesting that Brunswick females experience a number of failed attempts at breeding prior to their first success. Aroclor 1268 levels were associated with decreases in health indicators. Strongest associations were with alkaline phosphatase and albumin; for both, low measures have been associated with substantial increase in mortality risk for dolphins. In addition, all three thyroid hormones decreased with increasing Aroclor 1268. Previous human studies have found that hypothyroidism is associated with infertility, miscarriage, and poor fetal outcome, suggesting a likely pathway for PCB-related effects on reproduction in bottlenose dolphins.
Source: Frontiers in Marine Science
Authors: Lori H. Schwacke, Len Thomas, Ryan Takeshita, Brian Balmer, Ashley Barratclough, Tracy K. Collier, Sylvain De Guise, Russell Clay George, Michel Gielazyn, Forrest M. Gomez, John Kucklick, Ross Martinson, Irvin Schultz, Brian Quigley, Kyle Ross, Todd Speakman, Nicole L. Vollmer, Randall S. Wells, Lynsey A. Wilcox Talbot, Ed Wirth, Gina M. Ylitalo, Eric Zolman, Teresa K. Rowles, Cynthia R. Smith
Institutions: Marine Mammal Commission, University of St Andrews, National Marine Mammal Foundation, Western Washington University, University of Connecticut, Georgia Department of Natural Resources, National Oceanic and Atmospheric Administration, NOAA National Ocean Service, NOAA Office of Response and Restoration, NOAA National Marine Fisheries Service, NOAA National Marine Fisheries Service Northwest Fisheries Science Center, University of Miami, NOAA National Marine Fisheries Service Southeast Fisheries Science Center, Mote Marine Laboratory, Brookfield Zoo Chicago
Language: English
Subfield: Health, Toxicology and Mutagenesis
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,801
OpenAlex ID: W7211899752