Dietary absorption efficiencies and toxicokinetics of polychlorinated biphenyls in ring doves following exposure to aroclor® mixtures

Abstract

Ring doves (Streptotpelia risoria) were fed a meal of pellets spiked with an Aroclor® mixture. Feces were collected from birds after fasting 31 h postexposure and dietary absorption efficiencies (AbE) of polychlorinated biphenyls (PCBs) were determined by mass balance. Polychlorinated biphenyl AbEs ranged from 0.86 to 0.97 for individual congeners and were similar to the lipid AbE of 0.90. The AbEs exhibited a declining trend with increasing chemical hydrophobicity. The toxicokinetics of PCBs and dietary lipids in blood plasma were also followed in the exposed birds for 25 h after feeding the contaminated meal. Despite decreasing trends in net AbEs with increasing chemical hydrophobicity, all PCBs exhibited similar blood toxicokinetics as observed for dietary lipids. The PCB plasma uptake rate constants exhibited a positive correlation with chemical hydrophobicity such that the most hydrophobic congener PCB 180 approached the plasma uptake rate constant measured for dietary lipids. Trends in assimilation kinetics of PCBs in blood were not consistent with the general prediction that solubility limitations of chemicals in the unstirred water layer (UWL) contribute to declines in net AbEs for highly hydrophobic chemicals. The data are consistent with a micelle‐mediated diffusion model, which indicates that dietary lipids and hydrophobic contaminants can cross the UWL and enter intestinal tissues at equivalent rates; however, solubility limitations of highly hydrophobic chemicals in mixed micelles may contribute to decline in net AbEs.

Bioaccumulation and biotransformation of 61 polychlorinated biphenyl and four polybrominated diphenyl ether congeners in juvenile American kestrels (Falco sparverius)

“…The term G represents the volume of contaminated oil (l/d) gavaged to the bird on a given day; AE is the chemical assimilation efficiency from ingested oil; k b is the congener-specific, wholebody elimination rate constant (1/d); and k g is the growth dilution rate constant (1/d). Initial simulations assumed AE to equal 0.95, because previous studies have established that dietary absorption efficiencies of PCBs in birds range from 0.9 to 0.97 [8]. The whole-body elimination rate constant (k b ) was estimated from PCB plasma clearance rate constants ( ; ml plasma/g BW/d) kЈ pc measured for adult male American kestrels [7].…”

“…Simulations also were performed using congener-specific PCB AEs as measured in ring doves [8]. Addition of congenerspecific AEs did not improve the model fit based on goodnessof-fit tests (data not shown).…”

“…Models describing PBTC bioaccumulation in avian wildlife have been developed [6,7], but relatively few examples of such models have been calibrated for key toxicokinetic parameters, such as dietary assimilation efficiencies [8] and elimination rate constants [6,7]. Even fewer studies have calibrated chemical toxicokinetics in a given species over different life stages (i.e., embryo [5,9,10], juveniles [11,12], and adults [6,7]).…”

Biological and chemical factors of importance in the bioaccumulation and trophic transfer of persistent organochlorine contaminants in arctic marine food webs

“…However, it was observed that many OCs increased in concentration with each trophic level in aquatic food webs, a process termed biomagnification. Uptake rates of most hydrophobic OCs are similar between species (see, e.g., [4]), and the elimination rate is what determines whether a chemical biomagnifies. Chemicals with fast elimination are less likely to biomagnify.…”

Polychlorinated biphenyls, dioxins, furans, and organochlorine pesticides in spotted sandpiper eggs from the upper Hudson River basin, New York

“…A number of studies have documented that birds can accumulate PCBs through their diet (Custer et al 1998(Custer et al , 1999(Custer et al , 2003(Custer et al , 2005Drouillard and Norstrom 2001;Froese et al 1998;Secord et al 1999). Effects of PCBs on birds, and especially on chickens (Gallus domesticus), which are extremely sensitive, have been clearly demonstrated in laboratory studies (Hoffman et al 1996b).…”