Serum concentrations of TCDD and other dioxin-like compounds in US Air Force veterans of Operation Ranch Hand

• We measured PCDDs, PCDFs and PCBs in serum of Vietnam War veterans (US Air Force).
• Median TCDD levels in 2002 were higher in Ranch Hands than in comparison veterans.
• Levels of other PCDDs, PCDFs and noPCBs did not differ substantially between groups.
• Levels of moPCBs did not differ substantially between Ranch Hands and comparisons.
• We also compared results to those from comparable age groups studied in NHANES.

We measured serum concentrations of seven dibenzo-p-dioxin congeners (PCDDs), ten dibenzofurans (PCDFs), four non-ortho polychlorinated biphenyls (noPCBs) and six mono-ortho polychlorinated biphenyls (moPCBs) in 1950 veterans of the Vietnam War. The veterans were participants in the Air Force Health Study (AFHS) who attended the final medical examination in 2002. Blood samples were collected from 777 Ranch Hands involved in the aerial spraying of herbicides in Vietnam and a comparison group of 1173 veterans (“Comparisons”) who served in Southeast Asia during the same time period. Results for moPCBs were based on a random subsample of 800 veterans.The median 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentrations in 2002 were 5.0 pg g−1 lipid in Ranch Hands and 2.2 pg g−1 lipid in Comparisons. No substantial differences were found in measured concentrations of other PCDDs, PCDFs, and noPCBs. Similarly, no substantial differences were found for moPCBs in the subsample. The median total dioxin toxic equivalent (TEQ) in Ranch Hands was 18.7 pg g−1 lipid for PCDDs, 3.4 pg g−1 lipid for PCDFs, and 3.2 pg g−1 lipid for noPCBs. Median TEQs in Comparisons were 14.4 pg g−1 lipid for PCDDs, 3.5 pg g−1 lipid for PCDFs, and 3.3 pg g−1 lipid for noPCBs. These TEQs, with the exception of PCDD TEQ in Ranch Hands (primarily due to elevated TCDD), were similar to or lower than those reported for similar age and gender groups in the 2001–2002 National Health and Nutrition Examination Survey (NHANES). These findings support the assumption that the Ranch Hand veterans were not more highly exposed to dioxin-like compounds other than TCDD than were Comparison veterans or the general US population.