Metabolic transformation shapes polychlorinated biphenyl and polybrominated diphenyl ether patterns in beluga whales (Delphinapterus leucas)

Environ Toxicol Chem. 2013 Apr;32(5):1132-42. doi: 10.1002/etc.2164. Epub 2013 Mar 29.

Abstract

While the accumulation of persistent contaminants in marine mammals can be attributed directly to their prey, the role of metabolism in shaping patterns is often overlooked. In the present study, the authors investigated the role of metabolic transformation in influencing polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) patterns in offshore and nearshore groups of beluga whales (Delphinapterus leucas) and their prey. Congener profiles and principal components analysis (PCA) revealed similar PCB and PBDE patterns in beluga whales feeding either offshore or nearshore, despite divergent contaminant patterns in the putative prey of these two feeding groups. The clustering of PCBs into metabolically derived structure-activity groups (SAGs) and the separation of metabolizable and recalcitrant groups along principal component 1 of the PCA revealed the important role of metabolic transformation in shaping PCB patterns in beluga. Lack of metabolism for congeners with high ortho-chlorine content was revealed by metabolic slopes equal to or greater than 1.0. Metabolic slopes for all other SAGs were less than 1.0 (p<0.001), suggesting metabolism of congeners with ortho-meta and meta-para vicinal hydrogens via induction of cytochrome P450 enzymes (CYP1A/2B/3A). Metabolic indices less than 1.0 for PBDEs (p<0.001) suggested that beluga metabolized these poorly understood flame retardants. The strikingly similar PCB patterns in a captive beluga and free-ranging beluga from the Beaufort Sea provide additional evidence that metabolic transformation is a dominant driver of contaminant patterns in beluga.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Beluga Whale / metabolism*
  • Cytochrome P-450 Enzyme System / metabolism
  • Environmental Monitoring
  • Female
  • Flame Retardants / metabolism
  • Halogenated Diphenyl Ethers / metabolism*
  • Male
  • Polychlorinated Biphenyls / metabolism*
  • Water Pollutants, Chemical / metabolism*

Substances

  • Flame Retardants
  • Halogenated Diphenyl Ethers
  • Water Pollutants, Chemical
  • Cytochrome P-450 Enzyme System
  • Polychlorinated Biphenyls