Differences in Toxicokinetics and Maternal Transfer between Lipophilic and Proteinophilic Halogenated Organic Pollutants in Laying Hens

Abstract

In this study, we conducted exposure experiments on egg-laying hens to explore the toxicokinetics and maternal transfer characteristics of lipophilic and proteinophilic halogenated organic pollutants (HOPs). The lipophilic HOPs included polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and dechlorane plus (DPs), while the proteinophilic HOPs included perfluorocarboxylic acids (PFCAs). The results revealed that most of lipophilic HOPs exhibit lower depuration rate (k _d) than PFCAs. The k _d of lipophilic HOPs correlated with the octanol-water partition coefficient (log K _OW) values in a V-shaped curve, whereas that of PFCAs correlated with the protein-water partition coefficient (log K _PW) values in an inverted V-shaped curve. The depuration rate, rather than the uptake rate, was a leading factor in determining the bioaccumulation potential of HOPs in hens. Although the dominant factors determining the tissue distribution of the two types of compounds were explicit (fats vs phospholipids), chemical-specific tissue distribution was still observed. The egg-maternal concentration ratio was dependent on the exposure status, concentration, and maternal tissue choice. Using a single maternal tissue may not be an appropriate method for assessing chemical maternal transfer potential. PFCAs have a greater maternal transfer potential (>80% of the total body burden) than lipophilic HOPs (approximately 30% for BDE209 and DPs, and less than 10% for the others). Their lipophilic and partly proteinophilic nature makes the toxicokinetics and maternal transfer characteristics of BDE209 and DPs different from those of other lipophilic HOPs. These findings are crucial for enhancing our understanding of the behavior and fate of HOPs in egg-laying hens.

Figure 1

Gastrointestinal absorption efficiency of HOPs in hens.

Figure 2

Relationship between the depuration rate constant (k_d) of lipophilic and proteinophilic HOPs in hens and the log K_OW and log K_PW value, respectively.

Figure 3

Bioaccumulation potential of lipophilic (a) and proteinophilic HOPs (b) calculated based on GAE/k_d.

Figure 4

Tissue distribution ratios (TDR) of HOPs in hens.

Figure 5

Relationship between the actual maternal transfer potential and log K_OW of HOPs.

Figure 6

Relationship between the maternal transfer ratios based on compound concentrations in different maternal tissues (a and b: Liver, c and d: Breast) and their log K_OW values.