PCDD/F and PCB concentrations in Arctic ringed seals (Phoca hispida) have not changed between 1981 and 2000

Area of Science:

• Environmental Science
• Toxicology
• Marine Biology

Background:

• Ringed seals are key Arctic marine mammals, acting as indicators of ecosystem health.
• Polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF), and polychlorinated biphenyls (PCBs) are persistent organic pollutants of concern in Arctic food webs.

Purpose of the Study:

• To quantify PCDD, PCDF, and PCB congeners in ringed seal blubber from Holman, NWT, across multiple decades.
• To assess temporal trends and age/sex-related differences in contaminant concentrations.
• To investigate the influence of atmospheric transport on PCB congener profiles in the Arctic.

Main Methods:

• Blubber samples from ringed seals collected in 1981, 1991, 1996, and 2000 were analyzed.
• Concentrations of PCDD, PCDF, and various PCB congeners (NO-CB, MO-CB, DO-CB) were measured.
• Statistical analyses were performed to evaluate temporal trends and differences based on age and sex.

Main Results:

• Total PCDD and PCDF concentrations remained consistently low and showed no significant temporal changes.
• Total PCB concentrations (NO-CB, MO-CB, DO-CB) did not change significantly over the study period.
• MO-CB and DO-CB concentrations increased with age in male seals, and were generally lower in females.
• Shifts in PCB congener distribution between the 1980s and 1990s indicate increased importance of atmospheric transport.

Conclusions:

• Ringed seal blubber exhibited stable concentrations of PCDD and PCDF from 1981 to 2000.
• While overall PCB levels were stable, changes in congener profiles suggest evolving pathways of PCB entry into the Arctic ecosystem, likely dominated by atmospheric deposition.
• Age and sex influence PCB accumulation patterns in ringed seals, highlighting differential exposure and metabolism.