Polychlorinated biphenyls in adipose tissue, liver, and brain from nine stillborns of varying gestational ages

We analyzed polychlorinated biphenyls (PCBs) in s.c. adipose tissue, liver, and brain of nine fetuses who died in utero. Their median (range) gestational ages and birth weights were 34 (17-40) wk and 2050 (162-3225) g. Three fetuses were small for gestational age. The levels of PCB congener nos. 118, 138, 153, and 180, and the sum of these (Sigma PCB), were calculated in terms of tissue total fat content (ng/g fat). The median (range) Sigma PCB (in ng/g fat) amounted to adipose tissue 235 (97-768), liver 198 (67-362), and brain 50 (22-122). Median (range) Sigma PCB levels in liver and brain were 0.8 (0.4-0.9) and 0.2 (0.1-0.3) times, respectively, as high as the Sigma PCB levels in adipose tissue. There were strong relations between Sigma PCB in adipose tissue and Sigma PCB in liver (r = 0.98; p <0.01), and between Sigma PCB in adipose tissue and Sigma PCB in brain (r = 0.91; p <0.01). Adipose tissue, liver, and brain did not show differences in the distribution of congeners 118, 138, 153, and 180, and there was no statistically significant association between tissue PCB levels and gestational age (r varied between 0.22 and 0.47). Median Sigma PCB levels in fetal adipose tissue proved to be comparable with our previously established Sigma PCB levels in mature breast milk of 93 Dutch women (median 414; range 158-969 ng/g of fat). The PCB congeneric distribution of fetal adipose tissue was not different from that of human milk. We conclude that maternal PCBs have a tendency to accumulate notably in fetal tissues with high triglyceride contents. They are easily transferred across the placenta and seem to become equilibrated among the apolar parts of maternal and fetal lipids.