Pathogen and Contaminant Exposure Data from Southern Beaufort Sea Polar Bears, 2007-2014

Polar bears were captured and sampled during helicopter flights over the sea ice. Bears were immobilized by firing a projectile containing an immobilizing agent from a dart gun. Blood samples were collected from immobilized bears and stored in the field in coolers with heating pads that prevented freezing during field operations. At the end of the day, samples were centrifuged and the serum and plasma were removed and immediately frozen. Samples were transported frozen from the field to either the USGS office in Anchorage, Alaska, where they were put into long-term storage in -80C freezers until the time of analysis.

Each serum sample was tested for antibodies to Brucella spp., C. burnetii, T. gondii, F. tularensis, and N. caninum. Plasma samples from a subset of individuals that had antibodies to one or more of these pathogens were used to quantify exposure to PCBs and OC pesticides. The buffered Brucella antigen card test and standard plate test (SPT) were used to assess exposure to Brucella spp., and a sample was considered positive if either the card test or SPT was positive. C. burnetii exposure was determined via indirect fluorescence assay with a cut-off titer of 1:128 considered positive for prior exposure (Duncan et al. 2012). The modified agglutination test was used for the detection of T. gondii with a cut-off titer of 1:25 (Dubey 1997). For N. caninum testing, a similar agglutination test was used (Neospora agglutination test; Dubey and Thulliez 2005). To test polar bears for prior exposure to F. tularensis, a commercial slide agglutination test was performed using serial dilutions of 1:20–1:320. F. tularensis antisera were tested in parallel with all polar bear sera to serve as positive controls. Polar bear sera reacting to antigen at a 1:20 or higher dilution were considered as putatively positive for prior exposure to F. tularensis. Concentrations of a suite of PCBs and OCs were quantified using a gas chromatograph coupled with a Quattro Micro tandem mass spectrometer (GC-MS/MS) system on a Rxi-5Sil GC column. PCBs were monitored by multiple-reaction monitoring (MRM), while OCs were monitored by selected ion monitoring (SIM). Samples were analyzed for 40 individual or co-eluting PCB congeners: CBs 18, 31/28, 44, 47/48/49/52, 66, 70/76, 74, 85, 87, 95, 99, 101/90, 105, 110, 118, 128, 130, 138, 146, 149, 151, 156, 157, 153, 170/190, 179, 180, 183, 184, 187, 195, 206, and 209. The OC pesticides included the ClBzs: 1,2,4,5-tetraClBz, 1,2,3,4-tetraClBz, PeClBz and hexachlorobenzene (HCB); hexachlorocyclohexanes (HCH): α-HCH, β-HCH; chlordanes (CHL): cis-nonachlor, trans-nonachlor, cis-chlordane, trans-chlordane, oxychlordane, heptachlor and heptachlor epoxide; aldrin; endosulfan: α-endosulfan, β-endosulfan; DDTs: p,p-DDE, p,p-DDD, p,p-DDT; dieldrin, mirex: mirex, photomirex; and, methoxychlor. Contaminant concentrations were reported on a mg kg−1 basis. For ClBzs, but not other OCs or PCBs, reported concentrations were recovery-corrected.