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Testimony on Birth Defects Among Vietnam Veterans' Children by J. David Erickson D.D.S., M.P.H., Ph.D. (CDC)
Chief, Birth Defects and Genetic Diseases Branch
Division of Birth Defects and Developmental Disabilities
National Center for Environmental Health
U.S. Department of Health and Human Services

Before the House Veterans' Affairs, Subcommittee on Hospitals and Health Care
April 16, 1997

Good morning. I'm Dr. Dave Erickson, Chief of the Birth
Defects and Genetic Diseases Branch, National Center for
Environmental Health of the Centers for Disease Control and
Prevention (CDC). I'm pleased to be here to provide testimony
about CDC's two studies on birth defects among children fathered
by veterans of the Vietnam conflict.

Major structural birth defects are common problems, affecting
3% or more of all babies. Birth defects are the leading cause of
infant mortality, accounting for 20% of all deaths during
infancy. If babies with birth defects survive, they usually
require extensive and expensive surgical and medical care; in
addition, many have lifelong disability. There are many
different types of birth defects. One of the more serious and
common specific kinds of defect is spina bifida, which is the
focus of our discussions today. It is characterized by an
improper formation of the vertebral column and spinal cord, as
shown in the diagram attached to the last page of my prepared
testimony. Babies born with spina bifida often survive, but they
are usually affected by lower body paralysis and bowel and
bladder incontinence. Anencephaly is a related malformation
characterized by improper formation of the skull and brain, also
shown in the attached diagram; babies born with anencephaly are
either stillborn or die shortly after birth. Some babies are
born with both spina bifida and anencephaly, and the two types of
defects are thought to have at least some common causes. CDC's
first study, published in 1984, was based on data collected from
families of babies born in the Metropolitan Atlanta area. Since
1967, CDC has gathered information on babies born with birth
defects in the five-county area surrounding and including the
city of Atlanta. This surveillance information identified about
5,000 families who had babies born from 1968 through 1980 with
major structural birth defects. We then compared the percentage
of fathers in this group who served in Vietnam with the
percentage among fathers of 3,000 babies who were born without
birth defects. If Vietnam veterans in general had been at
increased risk of having babies with birth defects, we would
expect to find a higher proportion of Vietnam veterans among
fathers of babies born with birth defects than among fathers of
babies born without birth defects. What we found, however, was
that 9.2% of fathers of babies with birth defects had served in
Vietnam, compared to 9.5% of fathers of babies born without
defects. Similarly, this study showed that Vietnam veterans in
general were not at increased risk of fathering babies with spina
bifida, or anencephaly.

At the time that the Atlanta study was done, there was no
feasible laboratory method for measuring Vietnam veterans'
exposure to the herbicide Agent orange, or its suspected toxic
contaminant, dioxin. Thus to try to evaluate the possible role
of these compounds in the occurrence of birth defects in children
of Vietnam veterans, we had to rely on other, less rigorous

One of these methods was to ask each Vietnam veteran father
whether he believed that he had been exposed to Agent Orange
during his tour of duty in Vietnam. The answers showed that
Vietnam veterans who thought that they had been exposed were no
more likely to have had a baby affected by anencephaly or spina
bifida than were Vietnam veterans who thought that they had not
been exposed.

In another attempt to evaluate the possible connection
between Agent Orange and birth defects, we constructed an index
of opportunities for exposure to Agent Orange based on Vietnam
veterans, military occupation and places and times of service in
Vietnam; the scoring of individual veterans on the index was done
by Department of Defense personnel. There was no association
between greater opportunities for exposure and the overall risk
of fathering a baby with all types of birth defects combined.
However, fathers who had greater opportunities for exposure, as
estimated by our index, did have a statistically significant
greater chance of fathering babies with spina bifida, although no
such association was found for the related defect anencephaly.
We found the association between spina bifida risk and fathers'
scores on the Agent Orange exposure opportunity index noteworthy.
But because of substantive uncertainties about the accuracy of
the index, we were inclined to attribute the finding to chance.
This inclination was strengthened by the lack of a parallel
association with the related defect, anencephaly.

The second CDC study related to birth defects, the
reproductive and child health component of the Vietnam Experience
Study (VES), which was published in 1989, compared the rates of
birth defects among babies fathered by about 7,900 Vietnam
veterans with the rates among babies of 7,400 control veterans
who did not serve in Vietnam. The veterans who participated in
this study had all served in the Army, and came from all parts of
the United States.

According to information obtained in telephone interviews
with veterans, 6.5% of 12,788 babies fathered by Vietnam veterans
had birth defects compared to 5.0% of 11,910 babies fathered by
control veterans. Notable among the defects were anencephaly and
spina bifida: they were reported in 0.09% babies of Vietnam
veterans but in only 0.04% of babies of control veterans.
Because of these findings, two substudies were added as
components of the VES study: the General Birth Defects substudy,
and the Cerebrospinal Malformations substudy.

The objective of the General Birth Defects substudy was to
compare rates of total birth defects recorded on hospital birth
records among children of veterans who served in Vietnam with
rates among children of veterans who did not. Records were
collected for children of only a subset of participating
veterans. According to these records, 7.3% of babies born to
Vietnam veterans had a birth defect, compared with 7.1% of
control veterans' babies; 2.9% of Vietnam veterans, babies had
major malformations compared with 2.4% of control veterans'
babies. No significant differences in spina bifida or
anencephaly rates were noted in this substudy, but the number of
affected babies was small. We believe that the results of this
substudy indicate that Vietnam veterans were not at a general
increased risk of fathering babies with defects. The higher rate
of birth defects reported by Vietnam veterans during the
interview phase of the study is thought likely due to
differential reporting by Vietnam and control veterans and was
not substantiated by review of objective hospital records.

In the Cerebrospinal malformations substudy, hospital records
were sought for a small subset of all babies reported to have
been fathered by participating veterans. These were babies who,
based on descriptions obtained in the interview, might be
suspected of having spina bifida or anencephaly. This substudy
was done to document from medical records cases of spina bifida
and anencephaly reported by telephone interview and to locate
additional cases that might not have been reported by veterans
during their interviews. The search for unreported cases is
considered important because many babies with spina bifida are
stillborn, and parents may not have been adequately informed
about the cause of the stillbirths. According to birth records,
the Vietnam group and the control group each had four stillborn
babies with spina bifida or anencephaly. Birth records also
showed that Vietnam veterans had eight live born babies with
spina bifida and seven with anencephaly, whereas control veterans
had two live-born babies with spina bifida and three with
anencephaly. A problem with this substudy, however, is that a
veteran had to report that his baby had some sort of problem for
that baby's records to be included. Thus a veteran's baby about
whom no problem was noted in the interview was not included in
this study. While the number of babies verified as having been
born with spina bifida or anencephaly was higher among Vietnam
veterans than among control veterans, the number observed among
Vietnam veterans' babies is consistent with national birth
defects data, whereas the number among control veterans' babies
is much lower. We have a number of reservations about these
data, and an important limitation of the study was that it did
not collect any information regarding potential exposure to Agent
Orange. Nevertheless, it was interesting that both CDC studies
had some potentially suggestive, albeit highly equivocal,
findings relative to spina bifida.

You have heard already this morning about the results on
spina bifida and anencephaly from the Air Force's Ranch Hand

Even though these data have raised our interest further, the
accumulative evidence is far from proving a cause and effect
relationship between exposure to Agent Orange and spina bifida.

The causes of most birth defects are unknown, and more
research is needed to identify causes so that these devastating
problems can be prevented in the future. While we are at the
present left with many questions about Vietnam veterans, risks
for having babies with spina bifida, the past decade has
witnessed a major breakthrough in our understanding of how a
large fraction of spina bifida and anencephaly cases can be
prevented. I want to close by telling you a bit about this
research success story, and in particular about how CDC's Atlanta
Vietnam veterans' birth' defects study played a critical role in
the establishment of the breakthrough.

In the CDC study, questions were included about maternal
vitamin use in the interviews done for the Atlanta Vietnam
veterans birth defects study. Analysis of these vitamin use data
showed that there was a much lower risk for having a spina bifida
or anencephaly- affected pregnancy among women who consumed folic
acid- containing vitamins. This finding was an important
unexpected benefit of our Vietnam veterans birth defects study.
As time went by, other research with similar findings

We now know that if women consume 400 micrograms of the
B-vitamin folic acid before conception and during early
pregnancy, their risk for having a pregnancy affected by spina
bifida or anencephaly can be cut in half. As a result, the
Public Health Service recommends that all women of reproductive
age should consume 400 micrograms of folic acid per day. Four
hundred micrograms is the amount of folic acid that is found in
most multivitamin pills. In a further unfolding of this
tremendous prevention opportunity, the Food and Drug
Administration has recently mandated the fortification of cereal
grain flours with folic acid to help women reach the recommended
level of consumption.

Although we have been unable to provide definitive answers
about Vietnam veterans' risks for fathering babies with spina
bifida, the studies conducted have contributed to the discovery
of a tremendous prevention opportunity for spina bifida and

That concludes my testimony. Thank you for your attention.
I will be happy to try to answer any questions you might have.

** Attached is an illustration of babies with Spina bifida and

"Spina bifida results from the failure of the spinal column to
close. Most babies with this condition live but with disabling
consequences which vary depending on the location of the open
area on the spine. With severe spina bifida, a person's legs and
feet are paralyzed, and there are problems with bowel and bladder
control. Learning disabilities are common and mental retardation
sometimes occurs."

"Anencephaly is marked by the incomplete development of the skull
bones and a partially or completely absent brain. Babies with
anencephaly all die before birth or shortly thereafter."

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