Dioxin Contamination Originated from the Use of Agent Orange in the Vietnam War
From 1962 to 1971, the U.S. military implemented Operation Ranch Hand during the Vietnam War. The operation involved spraying a large quantity of Agent Orange, an herbicide which contains 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic congener of dioxin. Production of Agent Orange ended in the 1970s. The TCDD used in the herbicide is now considered highly toxic and a persistent organic pollutant that is linked to cancers, diabetes, birth defects and other disabilities. Recently, researchers in Vietnam set out to investigate the effect of perinatal dioxin exposure as indicated by dioxins found in breast milk on children’s eye gaze behavior. To do this, the research team studied 142 three-year-olds from the 2012 Bien Hoa birth cohort, an area of extreme dioxin contamination due to Agent Orange use in the Vietnam War. The study’s design involved observing participant’s faces using the eye-tracking method. A cohort of boys and a cohort of girls in this research were studied separately. Associations between eye gaze behavior of faces and neurodevelopmental standards as well as head circumferences were also analyzed to determine if poor gaze behavior designated increased autistic traits in the study’s participants. In the end, the research team found that the three-year-old girls living in Bien Hoa showed atypical eye gaze behavior which were proportional to perinatal TCDD exposure. The girls who exhibited the atypical eye gaze behavior showed lower social communication scores and had a smaller head size, which has been associated in girls with autism. They did not find these same associations with the three-year-old boys in the study. The authors intend to follow up with the study’s participants to assess their behavior and hormonal levels in late childhood and adolescence.
