Fetal exposure markers of dioxins and dioxin-like PCBs
Environmental Science and Pollution Research
Fetal exposure markers of dioxins and dioxin-like PCBs
Erik Lampa 0
Akifumi Eguchi 0
Emiko Todaka 0
Chisato Mori 0
0 Center for Preventive Medical Sciences, Chiba University , Chiba , Japan
Fetal exposure to polychlorinated biphenyls (PCBs), polychlorinated-p-dibenzodioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) have been associated with a number of adverse health outcomes. Although the placenta acts as a barrier between the mother and the fetus, these contaminants transfer through the placenta exposing the fetus. Several studies have investigated placental transfer, but few have assessed the co-variation among these contaminants. Maternal blood, cord blood, and cord tissue were collected from 41 Japanese mother-infant pairs and analyzed for dioxin-like PCBs and PCDD/Fs. Hierarchical cluster analysis followed by principal component analysis were used to assess the co-variation. Two stable clusters of dioxin-like PCBs were found in maternal and cord blood. One cluster of low/medium chlorinated dioxin-like PCBs was present in all three matrices with 2,3',4,4',5-PeCB(#118) and 3,3',4,4',5-PeCB(#126) explaining the majority of the clusters' variances. Medium/high chlorinated dioxin-like PCBs clustered in maternal blood and cord blood but not in cord tissue. 2,3,4,4',5-PeCB(#114) and 2,3,3',4,4',5,5'-HpCB(#189) explained the majority of the clusters' variances. There was a substantial correlation between the sum of dioxin-like PCBs and total PCDD/F in all three matrices. The sum of the four suggested PCBs plus 3,3',4,4'-TeCB(#77) correlated well with total PCDD/F in all three matrices. Apart from the dioxin-like PCBs, little co-variation existed among the studied contaminants. The five PCBs can be used as fetal exposure markers for dioxin and dioxin-like PCBs in maternal and cord blood respectively. In cord tissue, more higher chlorinated dioxin-like PCBs need to be measured as well.
PCB; Dioxin; Fetal exposure; Multivariate analysis
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Introduction
Polychlorinated
p-dibenzodioxins
biphenyls
(PCDDs),
(PCBs),
and
polychlorinatedpolychlorinated
UCR - Uppsala Clinical Research Center, Uppsala Science
Park, Hubben, 751 85 Uppsala, Sweden
dibenzofurans (PCDFs) are widespread environmental
contaminants that have been associated with numerous
adverse health effects in humans such as increased cancer
risk
(Kogevinas 2001; Oakley et al. 1996)
, reproductive
disorders (Crain et al. 2008), and nervous system damage
(Grandjean and Landrigan 2006)
. Although the use and
production of them is banned in large parts of the world,
they continue to persist in the environment and accumulate
in human adipose tissue. Of special concern is the
exposure of a developing fetus because of potentially increased
vulnerability during critical development stages.
Epidemiological studies have linked maternal exposure to PCBs and
PCDD/Fs to health outcomes such as growth restriction
(Govarts et al. 2012)
, neurobehavioral deficits
(Grandjean
et al. 2001)
, and impaired immune response in the child
(Svensson et al. 1994)
. Accumulated contaminants are
passed from the mother to the fetus through the placenta and
the umbilical cord. Although the placenta acts as a barrier
protecting the growing fetus, PCBs and dioxins as groups
easily pass the placenta
(Lancz et al. 2014)
. However, PCBs
and PCDD/Fs are mixtures of different congeners, each
with their own physiochemical properties. Congeners with
lower molecular weight are more likely to pass the placenta
than congeners with higher molecular weight
(Eguchi et al.
2015; Mori et al. 2014)
. While placental transfer has been
investigated in several studies, few studies have investigated
the co-variation of PCBs and dioxins. The aim of this study
was to assess the degree of co-variation among dioxins and
dioxin-like PCBs in maternal blood, cord blood, and cord
tissue and to find suitable markers of exposure.
Material and Methods
Data collection
Maternal blood, umbilical cord blood, and cord tissue were
collected from 41 mother-infant pairs at Chiba University
Hospital and at various other obstetrics units in Japan during
2003 and 2004. Blood samples were stored at − 20 ◦C
until use. Umbilical cords were collected immediately after
delivery and stored in acetone-washed glass bottles at
− 20 ◦C until use. Concentrations of seven PCDDs, 10
PCDFs and 12 dioxin-like PCBs were measured in all
three matrices. TEQ-calculated values, using the WHO
2005 Toxic Equivalence Factors (TEF)
(Van den Berg et al.
2006)
, were used in all statistical analyses. Further details
on the data collection and chemical analyses can be found
in
Sakurai et al. (2004)
,
Kawashiro et al. (2008)
, and
Mori
et al. (2014)
. The age distribution of the mothers is given
in Table 1. The study was approved by the Congress of
Medical Bioethics at Chiba University, and all samples were
obtained after receipt of written informed consent.
Statistical met (...truncated)