In 1991 Congress mandated a series of studies every two years for 10 years examining the effects of herbicides, such as Agent Orange, that were used in Vietnam. From that work, researchers found compelling evidence that associated exposure to the chemicals with soft-tissue sarcoma, non-Hodgkin's lymphoma, Hodgkin's disease and chloracne, a skin disease, among other conditions. Now a new review of hundreds of these studies from the U.S. and abroad has uncovered another possible linkthis time between Agent Orange and the development of acute myelogenous leukemia (AML) in the children of Vietnam veterans.

"No firm evidence links exposure to the herbicides with most childhood cancers," says Irva Hertz-Picciotto, an epidemiologist from the University of North Carolina at Chapel Hill who chaired a panel of experts conducting the study, "but new research does suggest that some kind of connection exists between AML in children and their fathers' military service in Vietnam or Cambodia. Additional research is needed to shed more light on the issue."

The scientists estimate that Agent Orange spraying may have increased the risk of AML in veteran's children by 70 to 300 percent. "Two studies in particular support this conclusion," Hertz-Picciotto says. "One is a case-control study of AML in which self-reported service in Vietnam or Cambodia was associated with an elevated risk after adjusting for numerous potentially confounding lifestyle and sociodemographic factors. The other, a study of what illnesses children of Australian Vietnam veterans had been diagnosed with, found a greater than four-fold risk although most confounding factors were not controlled for."