Effects of Aroclor 1254 on the Thyroid Gland, Immune Function, and Hepatic Cytochrome P450 Activity in Mallards

Polychlorinated biphenyl effects on avian hepatic enzyme induction and thyroid function

“…It is possible that by 21 days after dosing, enough of the dose may have been metabolized and excreted that the effects of PCBs were reduced compared to five days after dosing. Other studies have shown that PCBs cause liver hypertrophy in birds (Elliott et al, 1997;Fowles et al, 1997;Riviere et al, 1978), which is consistent with my results after five days of exposure to the higher dose.…”

Thyroid Hormone Suppression and Cell-Mediated Immunomodulation in American Kestrels ( Falco sparverius ) Exposed to PCBs

“…In our study, T 3 proved to be more sensitive to suppression by PCBs than was T 4 . These findings concur with those of Fowles et al (1997b) in which Aroclor caused depression of serum T 3 in mallards (Anas platyrhynchos). The mechanism by which PCBs are interfering with circulating thyroid hormone levels cannot be determined from the current study.…”

“…Increasingly, immunotoxicology is being applied as a monitoring tool for evaluating the impacts of environmental contaminants on wildlife (Bishop et al 1998;Ross 1995;Smits et al 1996a. Immune function has been compromised in waterfowl (Fowles et al 1997b), upland game birds (Grasman and Scanlon 1995), and passerines (Smits and Williams 1999) exposed to a range of environmental pollutants.…”

Thyroid dysfunction in sea bass (Dicentrarchus labrax): Underlying mechanisms and effects of polychlorinated biphenyls on thyroid hormone physiology and metabolism

“…Polychlorinated biphenyls have been shown to alter thyroid hormone levels in experimental animals, including fish (Brouwer et al, 1989/7;Coimbra and Reis-Henriques, 2007;Collins and Capen, 1980a,b;Fowles et al, 1997;Hallgren, 2001Hallgren, , 2002Iwanowicz et al, 2009). Most studies on fish thyroidology have involved ambient concentrations of xenobiotics delivered at sublethal, concentrations that, however, are still higher than those encountered in the field (Blanton and Specker, 2007;Brown et al, 2004a).…”