|Age Group (Years)||Vietnam Era||Vietnam Theater|
SOURCE: IOM, 1994, Table 3-3, updated by 20 years.
evidence from epidemiologic studies regarding associations between exposure to the chemicals of interest (COIs)—2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and its contaminant 2,3,7,8-tetrachlo-rodibenzo-p-dioxin (TCDD), picloram, and cacodylic acid—and various types of cancer. The committee also considers studies of exposure to polychlorinated biphenyls (PCBs) and other dioxin-like chemicals (DLCs) informative if their results were reported in terms of TCDD toxic equivalents (TEQs) or concentrations of specific congeners of DLCs. However, studies that report TEQs based only on mono-ortho PCBs (which are PCBs 105, 114, 118, 123, 156, 157, 167, and 189) were given very limited consideration since mono-ortho PCBs typically contribute less than 10% to total TEQs, based on the WHO revised TEFs of 2005 (La Rocca et al., 2008; Van den Berg et al., 2006). If a new study reported on only a single type of cancer and did not revisit a previously studied population, its design information is summarized here with its results; design information on all other new studies can be found in Chapter 6.
The objective of this chapter is assessment of whether the occurrence of various cancers in Vietnam veterans themselves may be associated with exposure they may have received during military service. Therefore, studies of childhood cancers in relation to parental exposure to the COIs are discussed in Chapter 10, which addresses possible adverse effects in the veterans’ offspring. Studies that consider only childhood exposure are not considered relevant to the committee’s charge.
In an evaluation of a possible connection between herbicide exposure and risk of cancer, the approach used to assess the exposure of study subjects is of critical importance in determining the overall relevance and usefulness of find-