effects. Hence, more detailed and sophisticated latency analyses should be used in future research efforts.

The committee believes that experimental research into the mechanisms that underlie human health outcomes can provide valuable information related to risk of disease in Vietnam veterans. The central role of the AhR in animal models is clear, and AhR gene differences in animals clearly affect susceptibility to TCDD. Although work to date on the AhR in humans has been limited, variations in this specific genetic factor alone are likely to affect human susceptibility to the toxic effects of TCDD, other dioxin-like chemicals, and herbicide formulations containing these chemicals. However, in addition to the AhR, it is also clear from recent research that variations in the genetics regulating the expression or activity or other factors, including proteins interacting with the AhR as well as the gene products regulated by the AhR, are critical in determining susceptibility to TCDD and the type of toxic effect observed. Studies addressing the identification, distribution, and functional consequences of polymorphisms of the AhR and these other cofactors in human populations should be pursued.

IOM (Institute of Medicine). 1994. Veterans and Agent Orange: Health Effects of Herbicides Used in Vietnam. Washington, DC: National Academy Press.

IOM. 1996. Veterans and Agent Orange: Update 1996. Washington, DC: National Academy Press.

IOM. 1999. Veterans and Agent Orange: Update 1998. Washington, DC: National Academy Press.

IOM. 2000. Veterans and Agent Orange: Herbicide/Dioxin Exposure and Type 2 Diabetes. Washington, DC: National Academy Press.

IOM. 2001. Veterans and Agent Orange: Update 2000. Washington, DC: National Academy Press.

IOM. 2003a. Veterans and Agent Orange: Update 2002. Washington, DC: The National Academies Press.

IOM. 2003b. Characterizing Exposure of Veterans to Agent Orange and Other Herbicides Used in Vietnam: Interim Findings and Recommendations. Washington, DC: The National Academies Press.

IOM. 2003c. Characterizing Exposure of Veterans to Agent Orange and Other Herbicides Used in Vietnam: Final Report. Washington, DC: The National Academies Press.

IOM. 2004. Veterans and Agent Orange: Length of Presumptive Period for Association Between Exposure and Respiratory Cancer. Washington, DC: The National Academies Press.