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Abstract
Blood samples of pregnant women aged between 19 and 42 years at the time they gave
birth and milk samples from the same women following delivery were collected between
September 2000 and January 2003 from 169 participants living in an industrialized
area of Germany (Duisburg birth cohort study). All samples were analyzed for their
content of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) as well as
dioxin-like and indicator polychlorinated biphenyls (PCB). Levels of WHO-TEq were
in the range of 4.34-97.3 pg/g(lipid base) (median: 26.37, arithmetic mean: 28.36)
for blood, or 3.01-78.7 pg/g(lipid base) (median: 26.40, arithmetic mean: 27.27) for
milk, respectively. The four congeners 12378-PeCDD, 23478-PeCDF, 33'44'5-PeCB (# 126)
and 233'44'5-HxCB (# 156) contribute the main share to total WHO-TEq. The contribution
of PCDD/F in relation to PCB to total WHO-TEq was 60:40% in blood and 52:48% in milk.
Good correlations of the contaminant levels in lipid base between both matrices were
found. The distribution between blood and milk depends on the molecular weight of
the substances. Higher chlorinated PCDD/F- and PCB-congeners were found in 2-4-fold
higher concentrations in blood in relation to milk and the concentrations of lower
chlorinated PCB-congeners were up to 2-fold higher in milk in relation to blood. The
body burden of PCDD/F and PCB increases with age and decreases over the total nursing
period. Women who had lived outside highly industrialized countries showed lower concentrations
of PCDD/F and PCB. In some cases, elevated levels of PCB were observed when the women
had previously lived in Eastern Europe for a long time. In comparison with recent
data, the decline in human PCDD/F and PCB levels observed during the nineties seems
to have stopped. The individual exposures of the infants due to breastfeeding within
the first 18 months were calculated to be from 4.4 to 318 ng WHO-TEq (median: 106,
arithmetic mean: 118). The actual mean daily exposure of a breastfed infant can be
estimated to 131 pg WHO-TEq/kg(body weight).