Relationship of PCDD/F and Co-PCB concentrations in breast milk with infant birthweights in Tokyo, Japan

Objective: To observe how PCDD/F and Co-PCB concentrations in breast milk relate to infant birthweights in Tokyo, Japan. Study design: Breast milk samples were collected from 240 mothers (aged 25-34 years old) residing in Tokyo to measure the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs; 14 congeners), polychlorinated dibenzofurans (PCDFs; 15 congeners), and coplanar polychlorinated biphenyls (Co-PCBs; 12 congeners) in the breast milk fat. Individual milk samples (about 50 ml) were obtained 30 days after delivery, between the months of June and September in 1999 and 2000. The relationship of the infant birthweights with the PCDD/F and Co-PCB concentrations was observed. Results: The birthweights were negatively correlated the concentrations of many of the PCDD/F and Co-PCB congeners, with the mean toxic equivalent quantities (TEQs) of the Co-PCBs, and with the sum of the PCDD, PCDF and Co-PCBs, although their correlation coefficients were less than 0.200. Multiple regression analysis showed octachlorodioxin was statistically significant explanatory variate. Conclusions: There were slight relationship between the dioxins levels of breast milk and the birthweights of the infants.