An analysis of birth defects and developmental disabilities for children of participants of the Air Force Health Study.

Abstract

Analyses were conducted of the occurrence of eight general categories of birth defects and developmental disabilities for children fathered by participants of the Air Force Heath Study (AFHS). Participants were male Air Force veterans of the Vietnam War. Children were categorized into conceived before and after the start of the participant's Vietnam War service. Analyses accounted for correlation between outcomes for multiple children fathered by each of the participants. For each of the eight general categories of birth defects and developmental disabilities, the probability of its occurrence increased substantially for children conceived after compared to before the start of Vietnam War service. These results support the conclusion of an adverse effect on reproductive outcomes due to Vietnam War service. Data for children conceived after the start of Vietnam War service for participants with measured dioxin values were used to estimate dose-response curves for the effect of dioxin exposure on the occurrence of each of the eight general categories of birth defects and developmental disabilities. These curves were assumed to be constant up to a threshold and then monotonic after that threshold. For seven of the eight general categories of birth defects and developmental disabilities, the estimated dose-response curves increased nonlinearly after associated thresholds. These results support the conclusion that the adverse effect to conception after the start of Vietnam War service may be attributable to high enough exposures to dioxin, a toxic contaminant of Agent Orange used for herbicide spraying in the Vietnam War.