Characterization of placental transfer of polychlorinated dibenzo-p-dioxins, dibenzofurans and polychlorinated biphenyls in normal pregnancy.
OBJECTIVE
Prenatal exposure to dioxins may result in many adverse health effects. However, the mechanisms by which dioxins are transferred from mother to fetus through the placenta are not well understood. The aim of this study was to investigate the differences in dioxin concentrations between maternal blood, the placenta, and cord blood in normal pregnant women, and to identify which individual congeners of these compounds are transferred from mother to fetus through the placenta.


METHODS
Samples were collected from 19 pregnant Japanese women. Specific congeners of seven polychlorinated dibenzo-p-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs), and four non-ortho polychlorinated biphenyls (PCBs) were analyzed.


RESULTS
The TEQ concentrations of PCDDs, PCDFs, and non-ortho PCBs were 8.03, 3.39, and 3.95 pg TEQ/g lipid, respectively, in the maternal blood; 8.78, 3.61, and 0.87 pg TEQ/g lipid in the placenta; and 4.33, 1.25, 1.08 pg TEQ/g lipid in the cord blood. Among specific congeners, 1,2,3,7,8-PentaCDD and 2,3,4,7,8-PentaCDF exhibited a placenta to maternal blood ratio greater than 1.0, while OctaCDD exhibited the greatest cord blood to placenta ratio. The cord blood to maternal blood ratio of total PCDDs was significantly higher than that of total PCDFs and total non-ortho PCBs.


CONCLUSIONS
The dioxin concentration in cord blood was approximately half of the amount in maternal blood, despite congeners showing a high toxic equivalency factor accumulating in the placenta. PCDDs were transferred more readily than PCDFs and non-ortho PCBs from maternal blood to the fetus through the placenta.
Department of Obstetrics, Fukuoka Children's Hospital Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University Fukuoka Institute of Health and Environmental Science, Fukuoka Department of Environmental Health, University of Occupational and Environmental Health, Kitakyushu, Japan.
Kiyomi
K
Tsukimori
Seiichi
S
Morokuma
Tsuguhide
T
Hori
Koji
K
Takahashi
Teruaki
T
Hirata
Yuka
Y
Otera
Kotaro
K
Fukushima
Toshihiro
T
Kawamoto
Norio
N
Wake
D000328:Adult; D001572:Benzofurans / Q000097:blood*; D005260:Female; D005312:Fetal Blood; D006801:Humans; D007564:Japan; D008431:Maternal-Fetal Exchange / Q000502:physiology*; D011078:Polychlorinated Biphenyls / Q000097:blood*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000097:blood; D011247:Pregnancy
D001572:Benzofurans; D000072317:Polychlorinated Dibenzodioxins; C023614:dibenzofuran; D011078:Polychlorinated Biphenyls