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We studied the risk of hypertension and exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in veterans of Operation Ranch Hand, the Air Force unit responsible for the serial spraying of Agent Orange and other TCDD-contaminated herbicide in Vietnam. We included a Comparison group of other Air Force veterans who flew or serviced C-130 cargo aircraft in Southeast Asia during the same calendar period that the Ranch Hand unit was active in Vietnam (1962-1971) but were not involved with spraying herbicides. We measured TCDD serum level in 1987, 1992, and 1997. There was no overall increase in the risk of hypertension in the Ranch Hand cohort, however, within both cohorts, the risk of hypertension was markedly increased with TCDD. Relative to the bottom category of serum TCDD in the Comparison cohort, the relative risk of hypertension in the highest TCDD category in the Comparison group was 1.66 (95% CI 1.04 to 2.67) and 1.33 (1.02 to 1.74) in the highest TCDD category in the Ranch Hand group. an analysis of a questionnaire-based index of skin exposure to herbicides among Ranch Hand enlisted personnel revealed an increasing trend (p=0.002) of hypertension risk with increasing skin exposure. While the lack of an overall between-group difference in hypertension risk suggested that TCDD was not a risk factor for hypertension, these within-group associations suggested that mechanisms relating TCDD uptake and clearance were associated with body weight and the pathophysiology of hypertension.

We studied the risk of hypertension and exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in veterans of Operation Ranch Hand, the Air Force unit responsible for the serial spraying of Agent Orange and other TCDD-contaminated herbicide in Vietnam. We included a Comparison group of other Air Force veterans who flew or serviced C-130 cargo aircraft in Southeast Asia during the same calendar period that the Ranch Hand unit was active in Vietnam (1962-1971) but were not involved with spraying herbicides. We measured TCDD serum level in 1987, 1992, and 1997. There was no overall increase in the risk of hypertension in the Ranch Hand cohort, however, within both cohorts, the risk of hypertension was markedly increased with TCDD. Relative to the bottom category of serum TCDD in the Comparison cohort, the relative risk of hypertension in the highest TCDD category in the Comparison group was 1.66 (95% CI 1.04 to 2.67) and 1.33 (1.02 to 1.74) in the highest TCDD category in the Ranch Hand group. an analysis of a questionnaire-based index of skin exposure to herbicides among Ranch Hand enlisted personnel revealed an increasing trend (p=0.002) of hypertension risk with increasing skin exposure. While the lack of an overall between-group difference in hypertension risk suggested that TCDD was not a risk factor for hypertension, these within-group associations suggested that mechanisms relating TCDD uptake and clearance were associated with body weight and the pathophysiology of hypertension.

1Robert's Rules of Order

By Henry M. Robert

Originally written in 1876 by Major Henry M. Robert of the US Army Corps of Engineers, <i>Robert's Rules of Order</i> is the most widely used authority in the United States today for "parliamentary law, based...upon the rules and practice of Congress" for "organizing and conducting the business of societies, conventions, and other deliberative assemblies." (Summary by TriciaG and from Preface)