Concentration-Dependent Changes of PCB Patterns in Fish-Eating Mammals: Structural Evidence for Induction of Cytochrome P450

Abstract

Data sets on CB concentrations in fish-eating mammals from five laboratories were combined to test and refine a pharmacokinetic model. Clear differences in PCB patterns were observed between species. The ability to metabolize chlorobiphenyl (CB) congeners with vicinal H-atoms only in the ortho- and meta-positions and with one ortho-chlorine substituent generally increased in the order otter < cetaceans (harbor porpoise, common dolphin) < phocid seals (harbor and grey seal), but the metabolism of congeners with vicinal H-atoms in the meta- and para-positions and with two ortho-chlorines increased in the order cetaceans < seals < otter. Both categories of congeners are probably metabolized by different families of cytochrome P450 (1A and 2B) of which levels apparently differed between the cetaceans, the pinnipeds, and the otter. Within-species CB patterns differed in a concentration-dependent manner. The induction of cytochrome P450 enzymes offers the most likely explanation for this phenomenon, but starvation could have a similar effect on occasion.

Bioaccumulation of persistent organic pollutants in female common dolphins (Delphinus delphis) and harbour porpoises (Phocoena phocoena) from western European seas: Geographical trends, causal factors and effects on reproduction and mortality

“…Since many compounds were often below their limit of detection, we finally selected five PBDE congeners (BDE47, BDE99, BDE100, BDE153 and BDE154) for further analysis. For the determination of total (a-, b-, and g-) hexabromocyclododecanes (HBCDs) at NIOZ, elution of the silica column was performed with 30 ml of an 85% pentane/15% diethyl ether mixture, an alteration required particularly for measurement of the b-isomer (Boon et al, 2002;Zegers et al, 2003). Cefas conducted analyses for HBCD on an individual diastereoisomer basis using LCeMS (Law et al, 2006b).…”

“…Certain chlorinated biphenyls can be metabolised by cytochrome P-450. Although the ability to metabolise PCBs was previously thought to be less well developed in cetaceans than in pinnipeds (Boon et al, 1997), implying that cetaceans may be more sensitive to effects of exposure to POPs, more recent evidence (reviewed by Hall et al, 2006) suggests that this may not be the case. Immunoreactive proteins recognised by heterologous CYP2B antibodies are present in several cetaceans including harbour porpoises (White et al, 1994;Goksøyr, 1995;Hummert et al, 1995) and CYP1B-like amino acid sequences are present in striped dolphin cDNA (Godard et al 2000).…”

A non-invasive approach to study lifetime exposure and bioaccumulation of PCBs in protected marine mammals: PBPK modeling in harbor porpoises

“…Congeners PCB 180 (group I), PCB 101 (group II), PCB 118 (group IIIa) and PCB 170 and PCB 99 (group IIIb) were chosen because of their persistence in marine mammals. A model for PCB 149 (group II) was developed as well because of its typically higher concentrations in cetaceans compared to pinnipeds (Boon et al, 1997).…”

Organochlorines in harbour porpoises (Phocoena phocoena) stranded along the southern North Sea between 2010 and 2013

“…1,2,19,20 It has been documented that CB 153 levels are higher in the majority of the samples from aquatic mammals. 21,13 The levels of CB 153 in juvenile harbour porpoises from this study (Table 1) ranged between 0.3 and 54 mg g À1 lipids. These levels were generally higher than those reported in immature male porpoises (1985)(1986)(1987)(1988)(1989)(1990)) from the Baltic Sea (1.1-13 mg g À1 lipids) and the Kattegat-Skagerrak Seas (1.0-10 mg g À1 lipids).…”

“…1,22,28,29 Marine mammals have induced levels of cytochrome P450-1A and 2B that are capable of metabolizing p,p 0 -DDT. 13 Thus, relatively high concentrations of DDT metabolites (p,p 0 -DDE and DDD) in marine mammal tissues were related to the higher metabolism of DDT in marine mammals along with the bioaccumulation of DDT metabolites through their life span. 30 In addition, ratios of p,p 0 -DDE/ P DDXs may indicate whether a new source of DDT is entering the environment.…”