CHAPTER 2 AGENT ORANGE AND OTHER HERBICIDES USED IN VIETNAM What is Agent Orange? Agent Orange is the name given to a specific blend of herbicides used for military purposes in Vietnam from 1965 to 1971. It was developed by the U.S. military for the purpose of eliminating plants and leaves from foliage in Vietnam that could have provided cover to the enemy. Vietnam veterans were exposed to many different health risks during the Vietnam War, including infectious diseases, smoke, unsanitary conditions, etc. However, Agent Orange remains even today a central focus for concerns about long-term health consequences of service in that war, among veterans, their families and others. The name “Agent Orange” came from the orange identifying stripe around the 55-gallon drums in which it was stored. The name did not refer to the herbicide’s actual color -- the material inside the drums was actually a reddish-brown to tan colored liquid. Other herbicides, including Agent White and Agent Blue, each with their own color-coded stripe, were also used in Vietnam to a lesser extent. The two herbicides or “active ingredients” mixed together to make Agent Orange had been developed and tested for military use in Vietnam by the U.S. military. Their tests came up with an optimized mixture containing about equal amounts of 2,4-D (2,4Dichlorophenoxyacetic acid) and 2,4,5-T (2,4,5-Trichlorophenoxyacetic acid). Both of these are in a common class of herbicides often referred to as the “chlorophenoxy herbicides.” At one time, chlorophenoxy herbicides were some of the most widely used weed-killing chemicals domestically in the United States, although generally at lower application rates compared to what was used in Vietnam. These agents as a class were inexpensive and effective at controlling weeds, and because they were generally regarded as safe, they were widely used by private citizens, businesses, and state and federal organizations in the United States. Their wide application spanned from the 1950’s through the 1970’s, when the U.S. Environmental Protection Agency banned the use of 2,4,5-T. In fact, the herbicide 2,4-D is still available for use in the United States today. Unfortunately, during the manufacture of one of the two herbicide ingredients of Agent Orange, the 2,4,5-T, small but significant amounts of the chemical dioxin (2,3,7,8Tetrachlorodibenzodioxin, or “TCDD”) was formed as a contaminating byproduct. Knowledge that Agent Orange and other herbicides used in Vietnam were contaminated with dioxin surfaced in the 1970s, and dioxin health effects have remained a major focus of health concerns for Vietnam veterans even today. Although dioxins are actually a class of closely related chemical compounds, the main dioxin contaminating Agent Orange was specifically one compound, TCDD. Today, TCDD is the most thoroughly examined dioxin in both animals and human studies, and it is considered to be the most hazardous of the dioxin chemical family. In fact, dioxins are produced as byproducts through a variety of processes including certain chemical manufacturing processes, waste incineration, and even in outdoor fires including forest fires and field burning. According to a recent draft risk assessment of dioxin health risks
Posted on: Fri, 13 Sep 2013 12:03:02 +0000
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