Levels and Toxicokinetic Behaviors of PCDD, PCDF, and Coplanar PCB Congeners in Common Cormorants from Lake Biwa, Japan

Abstract

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs) were determined in the liver and pectoral muscle of common cormorants (Phalacrocorax carbo) collected from Lake Biwa, Japan. To clarify the toxicokinetic behaviors and potential toxicities of these chemicals, the present study addresses life-stage- and tissue-specific accumulation of the congeners. Total 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) were in the range of 360 to 50,000 pg/g lipid weight in the liver and 310 to 12,000 pg/g lipid weight in the pectoral muscle. Among congeners, for which toxic equivalency factors were assigned, PCB126, 2,3,4,7,8-P5CDF, and 1,2,3,7,8-P5CDD made a greater contribution to total TEQs in the liver. Hepatic concentrations of T4- to H6CDDs, P5- and H6CDFs, and Co-PCBs (except PCB77) significantly increased with growth of cormorants, leading to life-stage-related compositional changes. The concentration ratios of liver to pectoral muscle revealed preferential accumulation of higher chlorinated congeners in hepatic tissue. For most congeners, concentration ratios significantly increased with an increase in hepatic total TEQs, suggesting their concentration-dependent hepatic sequestration. These results imply the presence of hepatic binding protein(s) such as cytochrome P450, inducible by these chemicals, which mayfunction as a binding species different from aryl hydrocarbon receptor. On the basis of these results, we conclude that the toxicokinetic behavior of each congener is life-stage-, tissue-, and concentration-dependent. TEQs in wildlife populations exposed to multiple congeners with varying concentrations should be used with caution for risk assessment, even within a species.

Dioxin‐like and perfluorinated compounds in pigs in an Indian open waste dumping site: Toxicokinetics and effects on hepatic cytochrome P450 and blood plasma hormones

“…An in vitro study using hepatic microsomes from rats pretreated with AhR agonists showed rapid metabolism of PCB77 and 2,3,7,8-T 4 CDF by CYP1A enzymes [36][37][38]. In addition, our recent studies indicated preferential metabolism of PCB77 and 2,3,7,8-T 4 CDF in wild animals [12][13][14][15][16]. None of the mono-ortho PCB congeners was correlated with CYP1A-like protein levels, implying a relatively low contribution of these congeners for CYP1A induction.…”

“…A study using transgenic Cyp1a2 knockout mice demonstrated that CYP1A2 is responsible for hepatic sequestration of certain DRC congeners [11]. Our previous studies demonstrated that distribution ratios of certain DRCs between liver and other tissues increased with total 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) or CYP1A level in Baikal seals [12], common cormorants [13,14], jungle crows [15], and raccoon dogs [16], suggesting that hepatic sequestration of DRCs is dependent on CYP1A induction and TEQ levels. Furthermore, the potential of hepatic sequestration of DRCs varied among such species.…”

Gastrointestinal absorption, dynamic tissue-specific accumulation, and isomer composition of dechlorane plus and related analogs in common carp by dietary exposure

“…Sequestration of DP isomers by hepatic proteins could be a cause for their disposition in the liver although this was not identified (Li et al, 2013b). Exposure to xenobiotic pollutants such as polychlorinated dibenzo-p-diosins, polychlorinated dibenzo-furans, and coplanar PCBs may induce hepatic binding proteins leading to hepatic sequestration of the compounds (Kubota et al, 2004).…”

Dioxin-like compounds in sediments from the Daliao River Estuary of Bohai Sea: Distribution and their influencing factors

“…Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/ Fs) and polychlorinated biphenyls (PCBs), which are two classical groups of dioxin-like compounds, are known to be the most hazardous to ecological and human health, and thus caused worldwide concerns and extensive research (deBruyn et al, 2004;Kubota et al, 2004). To evaluate their potential risk to environmental matrixes, consensus toxic equivalency factor (TEF) values for PCDD/Fs and PCBs have been derived (Van den Berg et al, 1998).…”