title: Inhaling Benzene, Toluene, Nitrogen Dioxide, and Sulfur Dioxide, Disrupts Thyroid Function in Captive American Kestrels (Falco sparverius).
abstract: Research investigating the effects of air contaminants on biota has been limited to date. Captive adult female American kestrels (Falco sparverius) were exposed to a mixture of benzene (0.6 ppm), toluene (1 ppm), nitrogen dioxide (NO2; 2 ppm) and sulfur dioxide (SO2; 5.6 ppm), in a whole-body inhalation chamber. Thyroid axis responses to meet metabolic demands were examined through thyroid histology, plasma thyroxine (T4), and triiodothyronine (T3), and hepatic outer ring deiodination (T4-ORD). Plasma free (F) T3and T4were measured at baseline, and at 9 days and 18 days of exposure, whereas total (T) T3and TT4, thyroid histology and hepatic T4-ORD were determined at the final 18 day exposure. Inhalation of these contaminants significantly suppressed plasma FT4and TT4, and depleted follicular colloid and increased epithelial cell height at 18 days, and significantly altered the temporal pattern of plasma FT4. Significant histological changes in the follicular colloid:epithelial cell height ratio indicated sustained T4production and release by the thyroid glands. There was no effect on plasma FT3, TT3, or hepatic T4-ORD. We hypothesize that contaminant-related activation of the hypothalamus-pituitary-thyroid axis in the kestrels increased elimination of plasma T4through Phase II enzymes. Further research is required to test this hypothesis in wild birds.
authors.affiliation: Ecotoxicology and Wildlife Health Division, Science and Technology Branch, Environment and Climate Change Canada, 867 Lakeshore Rd., Burlington, Ontario Canada , L7R 4A6.
authors.forename: Kim J
authors.initials: KJ
authors.lastname: Fernie
authors.affiliation: Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary , 3280 Hospital Drive NW, Calgary, Alberta Canada , T2N4Z6.|Ross University , School of Veterinarian Medicine, Box 334, Basseterre, St. Kitts West Indies.
authors.forename: Luis
authors.initials: L
authors.lastname: Cruz-Martinez
authors.affiliation: Stantec Consulting Ltd., 500-311 Portage Ave., Winnipeg, MB Canada R3B 2B9.
authors.forename: Lisa
authors.initials: L
authors.lastname: Peters
authors.affiliation: IISD-Experimental Lakes Area, 111 Lombard Ave., Suite 325 Winnipeg, MB Canada R3B 0T4.
authors.forename: Vince
authors.initials: V
authors.lastname: Palace
authors.affiliation: Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary , 3280 Hospital Drive NW, Calgary, Alberta Canada , T2N4Z6.
authors.forename: Judit E G
authors.initials: JEG
authors.lastname: Smits