Dioxins in human breast milk in Vietnam

Abstract

Several decades after herbicide spraying ceased, dioxin concentrations in both the environment and humans remain elevated in the sprayed areas of South Vietnam. Human breast milk is a good internal exposure indicator for estimating an individual’s dioxin level. The concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and toxic equivalents (TEQs) in human breast milk in hot spots and sprayed areas were found to be significantly higher than those in the unsprayed areas. Likewise, dioxin concentrations in the breast milk of multiparae were lower than those of primiparae in the hot spots, and the sprayed and unsprayed areas, respectively. Dioxin exposure as a result of usual dietary intake was less affected in the sprayed area than in the non-sprayed area, thus suggesting that past exposure rather than present dietary intake may affect current dioxin concentrations in breast milk in the sprayed area. As far as adverse health effects in humans are concerned, the visual acuity of both eyes for people in the sprayed area was significantly lower than that for people in the nonsprayed area on the basis of the contrast acuity test. Cortisol and cortisone levels in the saliva of primiparae in the hot-spot area were significantly higher than those in the non-exposed area. The correlation between salivary cortisol and cortisone levels and the PCDD + PCDF TEQ levels of breast milk in the combination of hot spot and non-exposed area was significant according to the curve (bell type), whereas the curve for estradiol levels and dioxin exposure was U-shaped.