Veterans' Health Issues Main Index

Agent Orange and Diabetes

Page Updated on August 02, 2005

In 1982, 1985, 1987, 1992, 1997 and 2002, approximately 1,000 Ranch Hand and 1,300 Comparison veterans were examined and medical records for each veteran, his spouse and his children were retrieved and coded. In 1986, chemists at the Centers for Disease Control and Prevention (CDC) developed an assay for dioxin in serum and demonstrated its suitability as a substitute for the assay of dioxin in adipose tissue obtained by biopsy. Beginning in 1987, blood from willing participants was collected and assayed.

Through an interagency agreement, the Air Force has collaborated with CDC since 1986 to measure dioxin in serum samples from these veterans. In 1987 and thereafter, the serum dioxin measurement has been used as the exposure index in this study. The median current dioxin level in 872 Ranch Hands in 1987 was 12.7 parts per trillion (ppt), range: 0 to 617 ppt. The median level in 1,060 Comparisons was 4.2 ppt, range: 0 to 54.8 ppt. Ninety-nine percent of the Ranch Hand dioxin levels are less than 200 ppt and 99% of the Comparison levels are less than 13 ppt.

Air Force Health Study research is summarized below. All these findings have been published in peer-reviewed journals:

Mortality

We found increased numbers of deaths caused by cardiovascular disease in enlisted ground personnel and, in all Ranch Hands, increased numbers of deaths caused by diseases of the digestive system. Half of the increase in deaths caused by diseases of the circulatory system were caused by atherosclerotic heart disease and most of the deaths caused by diseases of the digestive system were caused by chronic liver cirrhosis. The suggested increases in mortality due to cardiovascular and digestive diseases could be caused by our inability to adjust for smoking and drinking. Smoking and drinking histories are available only for the subgroup of veterans who have attended the physical examinations, most of whom are still living.

Morbidity

Cancer

We assessed cancer incidence and mortality using national rates and contrasted cancer risk in each of three Ranch Hand dioxin exposure categories relative to Comparisons. The incidence of melanoma and prostate cancer was increased among white Ranch Hand veterans. Among veterans who spent at most 2 years in Southeast Asia, the risk of cancer at any site, of prostate cancer and of melanoma was increased in the highest dioxin exposure category. These results appear consistent with an association between cancer and both service in Vietnam and dioxin exposure.

Dermatologic conditions

We found no cases of chloracne in Ranch Hand veterans and no meaningful or consistent association between dioxin exposure and the prevalence of acne or the location of acne. Those results suggested that Ranch Hand exposure to dioxin was insufficient to produce chloracne or that the exposure may have caused chloracne that has resolved and is currently undetectable.

Diabetes

A study of dioxin and diabetes which found that glucose abnormalities, diabetes prevalence and the use of oral medications to control diabetes increased while time to diabetes onset decreased with dioxin. Serum insulin abnormalities increased with dioxin in Ranch Hand veterans without diabetes. These results suggest an adverse relation between dioxin exposure and diabetes mellitus, glucose metabolism and insulin production.

Hematological Effects

We found no important relation between dioxin body burden and red blood cell count, white blood cell count, hemoglobin, hematocrit, mean corpuscular hemoglobin concentration and erythrocyte sedimentation rate. Mean corpuscular volume, mean corpuscular hemoglobin and platelet count, however, generally increased with dioxin level at each of the four examinations. It is not known at this time whether these increases are indicative of adverse health in Ranch Hand veterans.

Immune Disorders

In a study of dioxin and immune system alteration, we studied delayed-type hypersensitivity skin test responses to Candida albicans, mumps, Trichophyton, and staphage lysate, lymphocyte measurements, immunoglobulin concentrations, the presence of a broad range of autoantibodies, and evidence of clonal B cells. Overall, we found no evidence of a consistent relation between dioxin exposure and immune system alteration.

Cognitive Function

We studied cognitive function and dioxin exposure in Ranch Hand veterans based on cognitive tests administered in 1982. Cognitive testing included the Wechsler Adult Intelligence Scale-revised (WAIS-R), the Wechsler Memory Scale (WMS), and the reading subtest of the wide-range achievement test (WRAT). We found significant and adverse decreases in mean WMS logical memory scores for both immediate and delayed recall among 275 Ranch Hands with the highest dioxin levels. No associations were found between dioxin and mean WAIS-R or mean WRAT scores.

Peripheral Neuropathy

In a study of peripheral neuropathy and dioxin exposure in Ranch Hand veterans, based on clinical measurements made in 1992 and 1997, we found a significant and adverse relation between probable peripheral neuropathy and dioxin exposure category. Probable peripheral neuropathy was defined as present if at least two of the following three outcomes were found bilaterally: 1) absent Achilles reflex, 2) abnormal vibration at the ankle, 3) abnormal pin prick (foot). The 210 Ranch Hand veterans with the highest dioxin levels experienced 5 times greater risk of probable peripheral neuropathy than Comparison veterans who did not spray herbicides.

Reproductive Outcomes

Preterm birth, intrauterine growth retardation (IUGR) and infant death.

In 1998 we completed a paper on preterm birth, IUGR and infant death. These outcomes were studied in relation to the fathers dioxin level extrapolated to the time of conception of the child and were restricted to live births.

We found no consistent or meaningful relation between paternal dioxin and preterm birth or infant death. The risk of IUGR was not increased in any exposure category.

The Sex of Children

A study of people exposed to dioxin after an industrial accident in Seveso, Italy, found an excess of female offspring in families with both parents highly exposed to dioxin. From 9 months after the accident, on July 10, 1976, to December 1984, the 9 mother-father pairs with the highest dioxin levels had 12 children, all of which were girls. We conducted a similar analysis and found no suggestion of a relation between paternal dioxin level and the sex of offspring. These findings suggest that, if the excess of female offspring seen in the Seveso study is male-mediated, the Ranch Hand exposure was not sufficient to produce the effect, or the effect is not male-mediated. We did not measure serum dioxin concentrations in the wives and partners of these veterans and their occupational exposures to dioxin or other chemicals are not known; we suspect, however, that as a group they have experienced only background exposure.

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