Thyroid disruption and oxidative stress in American kestrels following embryonic exposure to the alternative flame retardants, EHTBB and TBPH. (December 2021)

• Record Type: Journal Article
• Authors: Goodchild, Christopher; Karouna-Renier, Natalie K.; Henry, Paula F.P.; Letcher, Robert J.; Schultz, Sandra L.; Maddox, Catherine M.; Bean, Thomas G.; Peters, Lisa E.; Palace, Vince; Fernie, Kim J.
• Is Part Of: Environment international. Volume 157(2021)
• Publication Date: 2021-12
• Subjects: American kestrel -- Flame retardant -- Firemaster 550® -- Thyroid -- Oxidative stress; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2021.106826
• Languages: English
• ISSNs: 0160-4120

Abstract

Graphical abstract: Highlights: Toxicity of embryonic exposure (23 d) to EHTBB, TBPH assessed in American kestrel hatchlings. EHTBB altered thyroid gland mass, colloid, thyroxine, hepatic deiodinase activity. TBPH altered thyroid gland colloid and increased hepatic oxidative stress in hatchlings. EHTBB and TBPH caused physiological effects (e.g., altered heart, brain mass). Hatching success reduced in American kestrels exposed to one EHTBB dose (50 ng/g egg) only. Abstract: Brominated flame retardant chemicals, such as 2-ethylhexyl-2, 3, 4, 5-tetrabromobenzoate (EHTBB) (CAS #: 183658–27-7) and bis(2-ethylhexyl)-2, 3, 4, 5-tetrabromophthalate (TBPH) (CAS #: 26040–51-7), have been detected in avian tissues and eggs from remote regions. Exposure to EHTBB and TBPH has been shown to cause oxidative stress and altered thyroid function in rodents and fish, yet no controlled studies have examined potential adverse effects of exposure in birds. Because flame retardants have been detected in wild raptors, we used American kestrels ( Falco sparverius ) as a model raptor to determine whether in ovo exposure to EHTBB or TBPH affected growth, hatching success, oxidative stress, or thyroid function. We exposed kestrel embryos to nominal concentrations (10, 50, or 100 ng g −1 egg weight) of EHTBB and TBPH via egg-injection on embryonic day 5. Embryonic exposure (~23 d) to EHTBB increased thyroid gland mass, reduced glandular colloid and total thyroxine (T4) in hatchling males and females, whereas deiodinase enzyme activity increased in males but decreased in females. Hatchlings exposed to TBPH in ovo exhibited reduced colloid and increased oxidative stress. Although exposure to EHTBB and TBPH caused several physiological effects (e.g., heart and brain mass), only exposure to 50 ng g −1 EHTBB appeared to reduce hatching success. Our results suggest these flame retardants may be hazardous for predatory birds. Future research should evaluate long-term survival and fitness consequences in birds exposed to these chemicals.