Archives of Environmental Contamination and Toxicology

, Volume 53, Issue 2, pp 287–292

Increased Thyroid Hormone Levels in Tree Swallows (Tachycineta bicolor) on Reclaimed Wetlands of the Athabasca Oil Sands


  • Marie-Line Gentes
    • Department of Veterinary PathologyUniversity of Saskatchewan
  • Anne McNabb
    • Department of Biological SciencesVirginia Tech
  • Cheryl Waldner
    • Department of Large Animal Clinical SciencesUniversity of Saskatchewan
    • Department of Veterinary PathologyUniversity of Saskatchewan

DOI: 10.1007/s00244-006-0070-y

Cite this article as:
Gentes, M., McNabb, A., Waldner, C. et al. Arch Environ Contam Toxicol (2007) 53: 287. doi:10.1007/s00244-006-0070-y


The oil sands of Alberta, Canada are one of the world’s largest reserves of crude oil. Oil sands mining companies are now investigating the ecological impacts of reclamation strategies in which wetlands are used for the bioremediation of waste materials. To examine the endocrine disrupting potential of chemicals in Oil Sands Process Materials (OSPM), thyroid hormone concentrations were measured in plasma and thyroid glands of nestling tree swallows (Tachycineta bicolor) from wetlands partly filled with mine tailings. Plasma triiodothyronine (T3) concentrations and thyroxine (T4) content within thyroid glands were elevated in nestlings from OSPM sites compared to those from the reference site. Results suggested enhanced hormone synthesis by the thyroid glands independently of activation of the pituitary–thyroid axis, as well as increased deiodination of T4 into T3 in peripheral tissues. This might have resulted from exposure to oil sands associated chemicals such as polycyclic aromatic hydrocarbons and from environmental factors such as food availability. Modulation of thyroid function might have negative effects on metabolism, behavior, feather development, and molt, which could compromise postfledging survival.

Copyright information

© Springer Science+Business Media, LLC 2007