Does exposure to Agent Orange or service in Vietnam increase the likelihood of a veteran fathering a child with birth defects?

One of the most emotional aspects of the Agent Orange issue is the concern that exposure to herbicides in Vietnam may have caused or contributed to the risks of having babies with birth defects. Literally thousands of Vietnam veterans have children with abnormalities. Considering the fact that approximately 2.6 million veterans served in Vietnam and the fact that 3-6 percent of all children are born with some kind of defect, scientists expect to see many children with abnormalities among the offspring of Vietnam veterans. Unfortunately, in many instances scientists cannot explain what caused these birth defects.

Research has been conducted to determine whether exposure to Agent Orange or military service in Vietnam may have increased the risk of having children with birth defects. Based on the research completed to date, the overall answer seems to be "apparently not." In 1996, the National Academy of Sciences found that there is "limited/suggestive" evidence of an association between herbicide exposure and one rare birth defect, spina bifida. For information about spina bifida, see Agent Orange Brief, D11. The Australian birth defects study, the Centers for Disease Control (CDC) birth defects study, the Air Force Health Study (Ranch Hand), and the CDC Vietnam Experience Study all suggest that Agent Orange is not the most likely cause of the birth defects. Each of these investigations is briefly summarized below.

Case-Control Study of Congenital Anomalies and Vietnam Service (Birth Defects Study)

-Report to the Minister for Veterans' Affairs - January þ1983 - Prepared by J. W. Donovan and others. This Australian investigation involved examination of the hospital and laboratory records of infants born with birth defects in three populous areas of Australia between the years 1966 and 1979.

In all, 34 hospitals and 4 laboratories cooperated fully with the investigating team. Whenever the birth of an infant with a defect was found, it was matched to a healthy control infant born in the same hospital, to a mother of similar age, and as close as possible in time to the birth of the child with the defect. The fathers of both cases (for this study, a case is a baby with a birth defect) and controls (for this study, a control is a baby without a birth defect) were identified in 8,517 instances and those identified were compared with a list of every man who served in the Australian Army between 1962 and 1972, the period of Australian involvement in Vietnam. Fathers who served in the Army during this period were then classified according to whether they had served in Vietnam.

The important finding of the study is that 127 of the fathers of children with birth defects were Vietnam veterans and 123 veterans were among the fathers of healthy children. This indicates that there is no evidence that Army service in Vietnam increased the risk of fathering a child with a birth defect.

Vietnam Veterans' Risks for Fathering Babies with Birth Defects

- August 1984 - U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, Center for Environmental Health. Vietnam veterans' risks for fathering babies with major structural birth defects were assessed using a case-control study. Information regarding military service in Vietnam was obtained from interviews with mothers and fathers of babies in case and control groups and from review of military records.

Vietnam veterans did not have an increased risk of fathering babies with defects. Furthermore, Vietnam veterans who had greater estimated opportunities for Agent Orange exposure were not at greater risk for fathering babies with all types of defects combined.

Air Force Health Study (Project Ranch Hand II) - An Epidemiologic Investigation of Health Effects in Air Force Personnel Following Exposure to Herbicides

- Periodic reports on morbidity (health problems). The February 1984 Baseline Morbidity Study Results indicated that there were no significant differences between the Ranch Hand (the military unit that did most of the herbicide spraying in Vietnam) and control groups with regard to severe or moderate birth defects. Based on parental reports, however, Ranch Hand offspring showed significantly more minor birth defects (birth marks, etc.).

In 1992, the Air Force study compared blood dioxin levels with reproductive outcomes. All of the 791 Ranch Hands and 942 comparison subjects who have measured levels of dioxin in their blood were included in the study. It analyzed miscarriages, total adverse outcomes, total conceptions, birth weights, birth defects, birth defect severity, specific and multiple birth defects, and infant and neonatal deaths. In addition, the study looked at sperm counts and the percentage of abnormal sperm of study participants.

Investigations found no adverse relationship between dioxin and any of these reproductive outcomes, nor between dioxin and sperm count or percentage of abnormal sperm.

Health Status of Vietnam Veterans - Reproductive Outcomes and Child Health

- The Centers for Disease Control Vietnam Experience Study - May 1988. The Vietnam Experience Study was a multidimensional assessment of the health of Vietnam veterans. From a random sample of enlisted men who entered the U.S. Army from 1965 through 1971, 7,924 Vietnam and 7,364 non-Vietnam veterans participated in a telephone interview; a random subsample of 2,490 Vietnam and 1,972 non-Vietnam veterans also underwent a comprehensive medical examination. Children of Vietnam veterans were not more likely to have birth defects recorded on hospital birth records than were children of non-Vietnam veterans. The rates of total, major, minor, and suspected defects were similar among children of Vietnam and non-Vietnam veterans.

What did the National Academy of Sciences conclude about birth defects in its l993 report, entitled Veterans and Agent Orange - Health Effects of Herbicides Used in Vietnam?

The 832-page NAS report included the following statements:

There is little evidence of a statistical association between father's occupational exposure to herbicides or dioxin and birth defects among offspring. The available epidemiologic studies have been limited by a number of problems, especially inadequate statistical power for the evaluation of specific birth defects. Studies involving environmental exposure have yielded inconsistent results; furthermore, given the ecologic nature of the studies, the limited sample sizes (for specific defects), and the failure to verify reported birth defects, the evidence can be considered inadequate for an association

The results of available epidemiologic studies of Vietnam veterans are also inconsistent; some studies suggest a potential association with defects of the central nervous system and other systems, although others find no increased risk. As noted for other end points, the veteran studies were generally limited by inadequate size, marginal magnitude of the increased risk, and the failure to exclude bias and chance. Moreover, uncertainty regarding the assessment of exposure among Vietnam veterans and the limited evidence from other cohorts do not permit one to draw a conclusion about an increased risk of birth defects among the offspring of men exposed to herbicides in Vietnam. Future analyses of the Ranch Hand data may contribute important evidence regarding an increased risk of birth defects.

What did the NAS conclude birth defects in its 1996 update?

The 1996 update included the following statements:

There is limited/suggestive evidence between exposure to the herbicides considered in this report and spina bifida. There is inadequate or insufficient evidence to determine whether an association exists between exposure to herbicides and all other birth defects. The evidence regarding association is drawn from occupation and other studies in which subjects were exposed to a variety of herbicides and herbicide components.

Since the strongest associations are from studies of Vietnam veterans and there are some data suggesting that the highest risks were for those veterans estimated to have had exposure to Agent Orange (e.g., Ranch Hands), it therefore follows that there is limited/suggestive evidence for an increased risk in Vietnam veterans of spina bifida in offspring.

What can a Vietnam veteran now assume about the risks of birth defects?

Many Vietnam veterans have produced children with birth defects. Many Vietnam veterans now in or approaching their 50's have wives entering or in menopause. Therefore, it is likely that Vietnam veterans will be having fewer children. Nevertheless, there is no doubt that Vietnam veterans will continue to produce some children with birth defects.

The critical question is "Are Vietnam veterans more likely than other individuals men to produce children with birth defects?" Based on all we know from the scientific research described above and studies of dioxin-contaminated areas in Times Beach, Missouri, and Seveso, Italy (where investigators concluded "that the data collected contain no evidence that in the population of the Seveso area exposed to dioxin; there was greater risk of producing congenitally malformed offspring."), Vietnam veterans do not seem to be at increased risk of fathering children with birth defects (with the possible exception of spina bifida, for which there is "limited/suggestive" evidence of an association).

(A relatively small number of women served in Vietnam. It is unlikely that many of them were exposed to Agent Orange. Research is underway to learn more about what effects Vietnam service may have had on their health. At this point, there is no scientific evidence that women have mothered an unexpectedly high number of children with birth defects.)

What is VA doing to learn more about birth defects among the children of Vietnam veterans and veterans of other wars?

On May 24, 1996, VA announced a "solicitation for applicant to establish a research center for epidemiological, clinical, and basic science studies of environmental hazards and their effects on reproductive and developmental outcomes." On November 14, 1996, VA announced that the Louisville VA Medical Center was selected as the site of this center.

Where can a concerned veteran get additional information about birth defects?

In October 1985, VA published a monograph entitled "Birth Defects and Genetic Counseling." This publication was distributed to all VA medical center libraries in 1985. The March of Dimes Birth Defects Foundation is a source of information on this subject. The address is Professional Education, March of Dimes Birth Defects Foundation, 1275 Mamaroneck Avenue, White Plains, New York 10605. Other sources of information include the Easter Seal Society and the Spina Bifida Association of America.