Agent Orange study hits brick wall.

After using new blood sera tests, CDC concludes neither military records nor the self-assessments ofveterans are reliable guides to past exposure to dioxin IN 1967 and 1968 an area of South Viemam known as the III Corps tactical zone saw the war's heaviest spraying of the defoliant Agent Orange. So it was from the III Corps region that epidemiologists with the Centers for Disease Control (CDC) hoped to find subjects for a congressionally mandated study on the health effects of exposure to dioxin, or 2,3,7,8-tetrachlorodi-benzo-p-dioxin (TCDD), the compound that contaminated Agent Orange during the herbicide's manufacture. The search party appears to have run into an epidemiological brick wall. CDC has concluded that military records were not written with number-crunchers in mind. Nor are the self-assessments of veterans a reliable guide for identifying people with high levels of exposure to Agent Orange. What this means is that finding large numbers of exposed veterans for a broad-based epidemiological study would be both difficult and expensive, if not impossible. In recent weeks, CDC has made the rounds in Washington, delivering the politically charged news at a 6 August meeting of the science panel of the White House's Agent Orange Working Group and before a 27 August meeting of the long-running Agent Orange Advisory Panel, which serves the congressional Office of Technology Assessment (OTA). It is news that will certainly disappoint and anger many veterans who believe that dioxin-laced Agent Orange is responsible for a litany of health woes. Dioxin has been found to be highly toxic for some species of laboratory animals, but the link to disease in humans is still not known. CDC came to its conclusions after testing blood sera from "exposed" veterans stationed in the III Corps area between. 1967 and 1968 against a control group of veterans who served stateside and in Germany during the same years. Both groups' sera contained the same low levels of dioxin. It was a finding that took many by surprise, as it rubs against the popular belief that Viet-nam veterans were literally drenched by the herbicide. The history of CDC's Agent Orange Study is one in which science and politics are intertwined. Under pressure from veter-ans' groups, Congress in 1979 passed a law calling for a large-scale epidemiological study on the health effects of dioxin exposure. Originally, the Veterans Administration (VA) was handed the job, but it was transferred to CDC because it …