excluded that additional parameters like different food habits, trophic levels and
physiological conditions of these two species may also supply a partial explanation.
The first to attempt at the determination of enantiomeric excesses of PCB
enantiomers in terrestrial ecosystems, that is, in human milk, was made by Glausch
et al. (1994). But although they basically were able to separate the enantiomers of
standard compounds of the chiral PCBs 95, 132 and 149 by multidimensional gas
chromatography (MDGC) on Chirasil-dex columns, none of the first trials indicated
significant enantiomer enrichment in human milk. Subsequent further screening of
PCB132 in human milk extracts suggested the enrichment of the second eluted
enantiomer. However, the unambiguous determination of PCB132 enantiomers
turned out to be difficult. Reliable confirmation of the first results was attained by
application of MDGC with two differently polar achiral stationary phases for
pre-separation, as well as cGC-MS in the SIM mode. As a result, enantiomeric
ratios of PCB132 between 0.40 and 0.87 were observed in ten milk samples (Hardt
et al. 1994). Since Haglund and Wiberg used the same chiral selector as Glausch
et al., the elution order of PCB132 published by Haglund and Wiberg (1996) allows
the conclusion that in the human milk samples investigated by the latter authors (+)PCB132 was the more abundant enantiomer.
A Canadian Arctic study investigated the enantiomer-selective distribution of
chiral organochlorine pesticides and atropisomeric PCBs in wolverine livers (Gulo
gulo). Wolverine livers were collected at Kugluktuk (Coppermine; n ¼ 12) in the
western Canadian Arctic. In addition to atropisomeric PCBs, for the first time, the
residue patterns of several other achiral persistent organochlorine contaminants
(OCs) were reported in this species (Hoekstra et al. 2003a, b, c). The here-reported
results were also compared to OC concentrations and EFs of chiral contaminants in
Arctic fox (Alopex lagopus) from Ulukhaqtuuq (Holman, n ¼ 20), a closely related
species that scavenges the marine and terrestrial Arctic environment. High POPs
levels were confirmed in the here-investigated species, confirming previous screening studies. The EFs of several chiral organochlorine pesticides (α-HCH, cis- and
trans-chlordane, oxychlordane, heptachlor exo-epoxide) and PCB atropisomers
(PCB-136, 149) were non-racemic in Arctic fox and wolverine liver. These results
were found similar to those previously calculated in Arctic fox and polar bears from
Iceland and the Canadian Arctic (Klobes et al. 1998a, b, c; Hoekstra et al.
2003a, b, c).
Approximately 10 years after the discovery of PCBs in the environment (Jensen
1966), Jensen and Jansson reported on the identification of PCB methyl sulfones
(MeSO 2 -PCBs) in Baltic Grey seal blubber (Jensen and Jansson 1976). About
20 years later, MeSO 2 -PCBs were detected in fish, birds and mammals including
human tissues (Ellerichmann et al. 1998a, b, c). More recently, some of the MeSO 2 -
PCBs in biota have also been observed to be selectively and strongly retained in the
liver tissue of mammals including men. However, the mechanism for this selectivity
is still under investigation, although reversible protein binding plays a major role for
their retention in the liver. The most important sulfones bound in mammalian tissues
are 3-MeSO 2 -2,5,6,2
0 ,3
0 ,4
0 -hexachlorobiphenyl (abbreviated: 3-132), 3-MeSO 2 -
2,5,6,2
0 ,4
0 ,5
0 -hexachlorobiphenyl
(abbr.
3-149)
and
4-MeSO 2 -
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
179
physiological conditions of these two species may also supply a partial explanation.
The first to attempt at the determination of enantiomeric excesses of PCB
enantiomers in terrestrial ecosystems, that is, in human milk, was made by Glausch
et al. (1994). But although they basically were able to separate the enantiomers of
standard compounds of the chiral PCBs 95, 132 and 149 by multidimensional gas
chromatography (MDGC) on Chirasil-dex columns, none of the first trials indicated
significant enantiomer enrichment in human milk. Subsequent further screening of
PCB132 in human milk extracts suggested the enrichment of the second eluted
enantiomer. However, the unambiguous determination of PCB132 enantiomers
turned out to be difficult. Reliable confirmation of the first results was attained by
application of MDGC with two differently polar achiral stationary phases for
pre-separation, as well as cGC-MS in the SIM mode. As a result, enantiomeric
ratios of PCB132 between 0.40 and 0.87 were observed in ten milk samples (Hardt
et al. 1994). Since Haglund and Wiberg used the same chiral selector as Glausch
et al., the elution order of PCB132 published by Haglund and Wiberg (1996) allows
the conclusion that in the human milk samples investigated by the latter authors (+)PCB132 was the more abundant enantiomer.
A Canadian Arctic study investigated the enantiomer-selective distribution of
chiral organochlorine pesticides and atropisomeric PCBs in wolverine livers (Gulo
gulo). Wolverine livers were collected at Kugluktuk (Coppermine; n ¼ 12) in the
western Canadian Arctic. In addition to atropisomeric PCBs, for the first time, the
residue patterns of several other achiral persistent organochlorine contaminants
(OCs) were reported in this species (Hoekstra et al. 2003a, b, c). The here-reported
results were also compared to OC concentrations and EFs of chiral contaminants in
Arctic fox (Alopex lagopus) from Ulukhaqtuuq (Holman, n ¼ 20), a closely related
species that scavenges the marine and terrestrial Arctic environment. High POPs
levels were confirmed in the here-investigated species, confirming previous screening studies. The EFs of several chiral organochlorine pesticides (α-HCH, cis- and
trans-chlordane, oxychlordane, heptachlor exo-epoxide) and PCB atropisomers
(PCB-136, 149) were non-racemic in Arctic fox and wolverine liver. These results
were found similar to those previously calculated in Arctic fox and polar bears from
Iceland and the Canadian Arctic (Klobes et al. 1998a, b, c; Hoekstra et al.
2003a, b, c).
Approximately 10 years after the discovery of PCBs in the environment (Jensen
1966), Jensen and Jansson reported on the identification of PCB methyl sulfones
(MeSO 2 -PCBs) in Baltic Grey seal blubber (Jensen and Jansson 1976). About
20 years later, MeSO 2 -PCBs were detected in fish, birds and mammals including
human tissues (Ellerichmann et al. 1998a, b, c). More recently, some of the MeSO 2 -
PCBs in biota have also been observed to be selectively and strongly retained in the
liver tissue of mammals including men. However, the mechanism for this selectivity
is still under investigation, although reversible protein binding plays a major role for
their retention in the liver. The most important sulfones bound in mammalian tissues
are 3-MeSO 2 -2,5,6,2
0 ,3
0 ,4
0 -hexachlorobiphenyl (abbreviated: 3-132), 3-MeSO 2 -
2,5,6,2
0 ,4
0 ,5
0 -hexachlorobiphenyl
(abbr.
3-149)
and
4-MeSO 2 -
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
179