Organochlorine Contaminants in Loggerhead Sea Turtle Blood: Extraction Techniques and Distribution Among Plasma and Red Blood Cells

Abstract

Few studies have described the organochlorine (OC) contaminant concentrations found in sea turtle tissues. These studies have relied on the opportunistic sampling of either eggs or tissues from stranded carcasses. In this study, the use of whole blood samples as well as both blood components (plasma and red blood cells) were examined as a non-destructive alternative for monitoring OCs in free-ranging loggerhead sea turtles (Caretta caretta). Blood samples were collected from juvenile loggerhead sea turtles (n = 12) captured in Core Sound, North Carolina, USA and analyzed for 55 polychlorinated biphenyl (PCB) congeners and 24 OC pesticides by gas chromatography with electron capture detection and mass spectrometry. Using pooled loggerhead sea turtle whole blood, three different liquid:liquid extraction techniques were compared. Results were similar in terms of recovery of internal standards, lipids, and OC concentrations. An extraction technique, employing formic acid and 1:1 methyl-tert-butyl-ether:hexane, was found to be satisfactory. This method was applied to the extraction of OCs from whole blood, plasma, and red blood cell (RBC) samples from five loggerhead sea turtles. Plasma contained the highest OC concentrations on a wet mass basis, followed by whole blood and RBCs. The majority of each OC compound was found in the plasma rather than the RBCs, suggesting that OC compounds preferentially partition into the plasma. On average (SD), 89.4% (3.1%) of total PCBs, 83.4% (11.9%) of total chlordanes, 74.3% (15.1%) of mirex, 72.6% (4.8%) of total DDTs, and 80.1% (16.6%) of dieldrin were found in the plasma. The concentrations of total PCBs, mirex, total chlordanes, and total DDTs measured in both components of the blood significantly correlated to those in whole blood. These are the first reported OC concentrations in sea turtle blood. They were found to be similar to previously reported levels in blood components of humans and of reptiles from relatively clean sites, but lower than those measured in blood of fish-eating birds and marine mammals. The results indicate that blood, preferably plasma, can be used to detect and monitor OC contaminants in loggerhead sea turtles.