Metabolism and disposition of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin in ring‐necked pheasant hens, chicks, and eggs

Abstract

The T 1/2 for whole-body elimination of [3H]-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) derived radioactivity in ring-necked pheasant hatchlings was 13 d, whereas in adult hen pheasants that were not producing eggs it was 378 d. All TCDD-derived radioactivity in hen tissues was from the parent compound. The oral bioavailability of TCDD in the adult hen pheasant varied with the environmental matrix, with 30% of the dose absorbed from a suspension of earthworms, 33% absorbed from a soil suspension, 41% absorbed from a suspension of paper mill sludge, and 58% absorbed from a suspension of crickets. A cumulative dose of 1.0 micrograms TCDD/kg body weight, administered as weekly doses of 0.1 micrograms/kg for 10 wk, did not adversely affect hen condition or egg production. Under these exposure conditions, hens translocated about 1% of their cumulative TCDD dose to each of the first 15 eggs laid. All of the TCDD-derived radioactivity in the eggs was the parent compound and was confined entirely to the yolk; no TCDD was detected in egg albumin. We conclude that TCDD was more persistent in pheasant hens than in chicks and that egg laying was an important route of elimination in the hen.

Toxicity of 2,3,7,8-Tetrachlorodibenzo-p-dioxin to Several Ecological Receptor Groups: A Short Review

“…In turn, toxic effects at the individual level are associated with concentrations above 100 pg/g. These data are consistent with laboratory toxicity studies (Nosek et al, 1992a) for birds, which indicate that a threshold for embryo mortality would be expected in the range 100 to 500 pg/g. Braune and Norstrom (1989) reported a biomagnification factor of 21 for TCDD in gull eggs relative to alewives in Lake Ontario; this threshold is associated with a concentration in alewives of approximately 24 pg TCDD/g.…”

“…Developing mammalian fetuses are especially sensitive to TCDD, and maternal exposure results in increased frequencies of stillbirths. Among live births, exposure produces teratogenic effects such as cystic kidney, Ring-necked pheasant embryos Graded TCDD dosage in ovo TCDD injection (Day 0) through Day 28 posthatch LD of egg albumin-injected eggs was 1354 pg TCDD/g egg; LD of yolkinjected eggs was 2182 pg/g egg; no histopathological or morphological changes in 1-or 28-day-old chicks treated with up to 1000 pg/g egg; no TCDD-related signs of edema observed Nosek et al, 1992a Bluebird chicks Graded TCDD dosage in ovo…”

“…No histopathological or morphological changes in 8-day-old chicks; no TCDDrelated signs of edema observed Nosek et al, 1992a cleft palate, and spinal deformities (Ramel, 1978). Additionally, it is important to recognize the interactive effects of dioxins with other, often similar, chemicals.…”

Reproductive success of three passerine species exposed to dioxin-like compounds near Midland, Michigan, USA

“…Hatching success is used as one of the most sensitive endpoints for avian exposure assessment (Custer et al 2003, 2005; Nosek et al 1992, 1993; Powell et al 1996; Thiel et al 1988). It was predicted that increased time spent on-site would lead to greater site-specific exposure to contaminants, which would result in decreased hatching success later in the season.…”

Dietary exposure of three passerine species to PCDD/DFs from the Chippewa, Tittabawassee, and Saginaw River floodplains, Midland, Michigan, USA

“…Because of the elevated soil and sediment concentrations in the SA (Hilscherova et al 2003) and low avian dietary exposure thresholds (Custer et al 2005;Eisler 2000;Nosek et al 1992), the authors investigated the potential for the accumulation of PCDFs and PCDDs from invertebrates to resident insectivorous birds.…”