PCB levels in breast milk: data from the UNEP/WHO pilot project on biological monitoring and some other recent studies.

The levels of polychlorinated biphenyls (PCBs) in human milk provide an index of exposure of the mother to these compounds and enable the intake by the breast-fed child to be estimated. For valid comparisons between different studies, concentrations should be expressed on a milk fat basis. In a recently completed UNEP/WHO pilot project on monitoring of organochlorine compounds in human milk in ten countries, great emphasis was placed on analytical quality assurance. To obtain comparable data, a common procedure, that of Sawyer, was adopted for quantitation of PCBs, using Aroclor 1260 as standard. In addition, certain criteria (e.g., age and parity) were established for selection of the mothers to be sampled. In contrast to the situation with p,p'-DDT and p,p'-DDE, the levels of PCBs in human milk fat were higher in the European countries and Japan than in China, India and Mexico. In fact, PCBs were not detected in human milk in the latter three countries. Although PCBs were detected in some samples in the USA, the median level was below the limit of detection of the method used there (1 mg/kg fat). The median PCB levels reported from Belgium, Israel, Japan and Yugoslavia were 0.81, 0.45, 0.35 and 0.63 mg/kg fat, respectively. Higher median levels were reported from Sweden and the Federal Republic of Germany (0.97 and 2.1 mg/kg fat, respectively). The German samples were not analyzed by the Sawyer method.