Effects of Polychlorinated Biphenyls on Thyroid Hormones and Liver Type I Monodeiodinase in the Chick Embryo

Polychlorinated biphenyl effects on avian hepatic enzyme induction and thyroid function

“…Aroclors 1254 (Gould et al, 1997) and 1242 (at high doses only; Gould et al, 1997;Gould et al, 1999) had no effect on circulating T 3 concentrations, but they caused decreased femur lengths in chicken embryos. However, Gould et al (1999) found that Aroclor 1254 had no effect on femur length in chicken embryos, and the same authors (1997) found that low doses of Aroclor 1242 actually increased femur lengths in chicken embryos. These discrepancies between studies are likely due to different types and doses of PCBs and differences in species and ages of animals, warranting further investigation on the effects of PCBs on avian UDP-GT activity and thyroid function.…”

“…At low doses, Aroclor 1242 significantly increased plasma T 4 concentrations in chicken embryos (Gould et al, 1997), and an organochlorine mixture that included PCBs also increased plasma T 4 concentrations in adult ring doves (Streptopelia risoria; McArthur et al, 1983). Aroclors 1254 (Gould et al, 1997) and 1242 (at high doses only; Gould et al, 1997;Gould et al, 1999) had no effect on circulating T 3 concentrations, but they caused decreased femur lengths in chicken embryos. However, Gould et al (1999) found that Aroclor 1254 had no effect on femur length in chicken embryos, and the same authors (1997) found that low doses of Aroclor 1242 actually increased femur lengths in chicken embryos.…”

“…In addition, femur lengths are sometimes longer and sometimes shorter compared to controls in response to PCB exposure. At high doses, Aroclors 1254 and 1242 have been shown to decrease plasma T 4 concentrations in chicken embryos (Gould et al, 1999), but Aroclor 1254 had no effect on T 4 in another study on chicken embryos (Gould et al, 1997). At low doses, Aroclor 1242 significantly increased plasma T 4 concentrations in chicken embryos (Gould et al, 1997), and an organochlorine mixture that included PCBs also increased plasma T 4 concentrations in adult ring doves (Streptopelia risoria; McArthur et al, 1983).…”

“…In one study, it was shown that Aroclor 1242 and Aroclor 1254 decreased circulating T 4 concentrations after 21 days in chicken embryos (Gould et al, 1999). In another study, Aroclor 1254 had no effect on circulating T 4 concentrations after 17 days and Aroclor 1242 increased circulating T 4 concentrations after 17 days in chicken embryos (Gould et al, 1997).…”

Effects of in ovo exposure to 3,3′,4,4′‐tetrachlorobiphenyl (PCB 77) on heart development in tree swallow (Tachycineta bicolor)

“…Environmental exposure to PCBs has been linked to diverse adverse effects in birds and other species, including cancer [11,12], immune system dysfunction [13,14], decreased reproduction [15], endocrine disruption [16,17], and neurological and cognitive dysfunction [18]. In addition, environmental exposure to PCBs has been linked to effects on cardiovascular development in wild birds [19].…”