At the heart of this report is the question of whether Blue Water Navy veterans had the potential for exposure to the tactical herbicides used in Vietnam, specifically Agent Orange, and particularly the TCDD contaminant of that herbicide, and whether that exposure, if any, could lead to an increased risk of long-term adverse health effects. The committee’s approach was to ask

• Whether it is possible to demonstrate that Blue Water Navy personnel were or were not exposed to Agent Orange–associated TCDD, and

• Whether it is possible to state with certainty that exposure of Blue Water Navy personnel, taken as a group, was qualitatively different from that of their Brown Water Navy and ground troop counterparts.

The committee considered that the most appropriate approach for assessing the risks of long-term adverse health effects would be a risk-assessment framework. The framework begins with identifying the sources of Agent Orange and its TCDD contaminant and potential receptors (in this case, ground troops and Brown Water Navy and Blue Water Navy populations). The next step is to evaluate how Agent Orange could reach the receptors (for example, transport by soil, water, and air) and plausible routes of exposure (inhalation, dermal contact, and ingestion). The information on routes of exposure can be used in conjunction with toxicologic information to assess the health effects that TCDD may have on the receptors.

The committee began by gathering information on how Agent Orange had been used in Vietnam and the quantity and geographic range of its application. The committee also considered data on the magnitude of TCDD contamination of Agent Orange. After reviewing information on releases of Agent Orange to the environment, the committee explored the fate and transport of Agent Orange and TCDD in air, fresh and marine water, sediment, soil, and food to assess the plausibility of Agent Orange and TCDD exposure of those military personnel that did not actually handle the herbicide themselves. The committee attempted to identify any monitoring data on TCDD that had been gathered during or shortly after the Vietnam War. The committee also considered fate and