Associations between dietary intake and breast milk dioxin levels in Tokyo, Japan

BACKGROUND: The presence of dioxins in breast milk has gained much attention recently. However, in Japan the relationship between the consumption of different foods and the human breast milk dioxin concentrations is still unclear. METHODS: Breast milk was taken from 240 mothers residing in Tokyo, Japan to measure and analyze the concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar poly-chlorinated biphenyls contained in the fat. Individual milk samples were obtained from the mothers 30 days after delivery in 1999 and 2000. The data of the mothers' diets before pregnancy were collected by means of food frequency and amount estimation. Spearman correlation analysis and stepwise multiple linear regression were used to analyze the data. RESULTS: The concentrations of dioxins in breast milk were influenced mainly by the mother's age and history of breast-feeding. All the Spearman correlation coefficients were less than 0.20. Pork, roast ham, sausage, salt codfish and tempura had negative correlations with breast milk dioxins. CONCLUSIONS: History of breast-feeding and the mother's age should be considered and emphasized in this kind of analysis. The cause effect relationship between dietary intake and breast milk dioxin levels were still uncertain.