To clarify the association between dioxin concentrations in breast milk and food group intake in herbicide-sprayed and nonsprayed areas in Vietnam.

This survey was conducted in August 2007 in sprayed and nonsprayed areas, respectively. The interviews were performed using a questionnaire to obtain information on personal characteristics and usual dietary intake. Eighty mothers of sprayed area and 42 mothers of nonsprayed area participated in the study. Breast milk was analyzed for concentration of polychlorinated dibenzo- p -dioxins ( PCDDs ) and polychlorinated dibenzofurans (PCDFs).

Multiple regression analysis showed that location (sprayed or nonsprayed area) has the highest association with the toxic equivalents (TEQ)- PCDDs , TEQ-PCDFs, and TEQ-Total rather than other factors. In the sprayed area, the adjusted R ² values of regression were approximately 0.1. On the other hand, the adjusted R ² values in the nonsprayed areas were higher than those in the sprayed area, i.e., between 0.2 and 0.3, and showed that there were significant associations with body mass index (BMI) in all models.

Dioxin exposure was less affected by usual dietary intake in the sprayed area than in the nonsprayed area in Vietnam. It was clear that past exposure rather than present dietary intake may affect present dioxin concentrations in breast milk in the sprayed area in Vietnam. This study suggests that present dioxin concentrations in breast milk were maintained by continuous past exposure even after 30–40 years had passed.