Chiral
Polychlorinated Biphenyls (PCBs) in Bioaccumulation,
Maternal Transfer, and Embryo Development of Chicken
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Abstract
Polychlorinated biphenyls (PCBs)
and enantiomer fractions (EFs)
of PCB enantiomers (PCBs 95, 132, 135, and 149) were investigated
in soil and chicken feed, chicken (Gallus domesticus) tissues, eggs on 0, 7, and 14 days after the onset of incubation,
and newborn chick tissues. The EF values of PCBs 95, 132, and 149
changed significantly from soil to chicken tissues, and the values
in the liver exhibited the highest deviation from the racemic ratio,
indicating enantiomer-selective metabolism in hens. Congeners, which
are highly resistant to degradation, such as PCBs 138, 153, and 180,
exhibited the highest maternal transfer potentials when muscle and
liver were used to assess the maternal transfer. However, uniform
transfer ratios were observed for most of the PCB congeners when visceral
fat was used. The EFs of chiral PCBs in eggs either did not match
with muscle or with liver or were similar to those in visceral fat.
These results indicate that hens mainly mobilized visceral fat for
egg formation and PCBs were deposited in eggs by associating with
these lipid materials. Further enantiomeric enrichment of PCBs 95,
132, and 149 occurred in the newborn chick tissues. However, an opposite
enantioselectivity for PCB 135 in newborn chicks was observed. These
results indicate that the potential toxicity of PCB enantiomers to
newborn chicks may be different from that of adults