|
The Legacy Continues
By Betty Mekdeci
The soldiers are dying. But, even more tragically, the children
they have left behind are suffering. Sometimes at Birth
Defect Research for Children we hear from veterans, but
usually it is wives and children who send us poignant messages:
“I lost my husband from a cancerous brain tumor 13
months ago. My son has many disabilities, including Tourette’s
syndrome, mental retardation, mild cerebral palsy, hydrocephalus,
and he is profoundly deaf. He will never be able to live
on his own.”
“My father passed away in 1998. He had many health
problems, including type II diabetes. He was only 50 years
old. Agent Orange has been a part of my life from the moment
I was born. I was born without my right leg, several of my
fingers, and my big toe on my left foot. My mother had three
miscarriages. My younger brother (age 29) has to wear bifocals
and suffers from chronic joint pain.”
“I served four tours in Vietnam. We have three children:
one daughter with a heart defect, another with scoliosis
and digestive problems, and a son born with a defective optic
nerve that has left him blind in the right eye. There is
no history of birth defects on either side of our family.”
Since 1991, we have recorded thousands of such cases in
our National Birth Defect Registry.
Some 2.8 million Americans served in the Vietnam theater
of operations. Three-to-six percent of Vietnam veterans’ children
are born with some kind of birth defect (Emory University
School of Medicine reports a 3-4 percent birth-defect rate
among the general population). An impressive body of scientific
evidence points to increases in birth defects and developmental
problems in the children of Vietnam veterans and others exposed
to dioxin-like chemicals.
Agent Orange was a combination of two defoliants, 2,4,5-T
and 2,4-D contaminated by dioxin (TCDD), a toxic byproduct
of the chemical production process. More than 19 million
gallons of herbicides were sprayed in Vietnam between 1962-71.
More than 11.2 million gallons sprayed after 1965 were dioxin-contaminated
Agent Orange. Agents Purple, Pink, and Green used before
1965 were even more highly contaminated with dioxin.
According to Barry Commoner and Thomas Webster in their
2003 book Dioxins and Health, “the current scientific
evidence argues not only that dioxin is a potent carcinogen,
but that the non-cancer health and environmental hazards
of dioxin may be more serious than believed previously.” They
report that dioxin appears to act like a persistent synthetic
hormone that interferes with important physiological signaling
systems that can lead to altered cell development, differentiation,
and regulation. The most troubling consequence is the possibility
of reproductive, developmental, and immunological effects
at the levels of dioxin-like compounds present in the bodies
of the average person.
Since studies of Vietnam veterans exposed to herbicides
in Vietnam have found much higher levels of dioxin in their
bodies than the average person, these effects also should
be detectable in their children.
In 1996, the National Academy of Sciences found “limited/suggestive” evidence
of an association between Agent Orange exposure and spina
bifida, a neural tube defect, in the children of Vietnam
veterans. In 2000, Dr. H.K. Kang of the Environmental Epidemiology
Service of the Veterans Health Administration published a
study that found that the risk of moderate-to-severe birth
defects was significantly associated with the mother’s
military service in Vietnam. As a result of these findings,
the VA now funds assistance programs for spina bifida in
the children of male or female Vietnam veterans and for all
birth defects without other known causes in the children
of female veterans.
The Australian Department of Veterans Affairs (without acknowledging
a link to Agent Orange exposure) provides treatment to the
children of Vietnam veterans with spina bifida, cleft lip
or palate, acute myeloid leukemia, and adrenal gland cancer.
Other studies offer evidence that many more birth defects
may be associated with dioxin-contaminated herbicide exposure
in Vietnam. In 1990, an independent scientific review of
the literature was sponsored by Vietnam Veterans of America,
the American Legion, and the National Veterans Legal Services
Project. Seven prominent, independent scientists and physicians
on this Agent Orange Scientific Task Force concluded that
elevated incidences of birth defects in the children of Vietnam
veterans were found in several studies. These included spina
bifida, oral clefts, cardiovascular defects, hip dislocations,
and malformations of the urinary tract. In addition, defects
of the digestive tract and other neoplasms such as neuroblastoma
also were higher in Vietnam veterans’ children.
Aschengrau and Monson of the Harvard School of Public Health
conducted a study published in 1990 in the American Journal
of Public Health on paternal military service and the risk
of late pregnancy outcomes. The scientists reported that
Vietnam veterans’ risk of fathering an infant with
one or more major malformations was increased at a statistically
significant level.
The Air Force Ranch Hand study of Vietnam veterans involved
in herbicide spraying has been analyzed several times for
adverse reproductive outcomes. A 1995 analysis found modest,
but significant, increases in spontaneous abortion, defects
of the circulatory system and heart, all anomalies, major
birth defects, and some developmental delays in the Ranch
Hand veterans’ children. There also was an increase
in spina bifida in the children of Ranch Hand veterans with
high dioxin levels.
More recent studies have found additional evidence of increases
in birth defects in the children of both male and female
veterans. Researchers at the University of Texas, the University
of Queensland, and the University of Sydney collaborated
on a meta-analysis (a review of the combined data from many
studies) of Agent Orange and birth defects in the International
Journal of Epidemiology. They identified all studies from
1966-2002 that had examined an association between Agent
Orange or dioxin and birth defects. The study authors identified
22 studies, including thirteen Vietnamese and nine non-Vietnamese
studies.
Their review indicated that parental exposure to Agent Orange
was associated with an increased risk in birth defects. The
association increased with greater degrees of exposure rated
on intensity and duration of exposure. Although other researchers
have pointed out weaknesses in the studies of birth defects
from Vietnam, the birth defect association with Agent Orange
exposure was statistically significant even when the Vietnamese
studies were excluded.
Genetic damage in New Zealand Vietnam War veterans was investigated
in a study published this year in Cytogenetic & Genome
Research by researchers from the Institute of Molecular Biosciences
at Massey University in New Zealand. A significantly higher
frequency of genetic damage was found among New Zealand Vietnam
War veterans compared to a control group. The authors suggested
that New Zealand Vietnam veterans had been exposed to a harmful
substance that could cause genetic damage. Although the authors
recommended caution in interpreting specific health outcomes,
they concluded that genetic damage to any degree has the
potential to result in adverse health effects. The greatest
concern about genetic damage is that it can be passed on
to future generations.
Important new research on birth defects in the children
of Vietnam veterans was presented at the 2006 meeting of
the Society for Epidemiological Research in Boston. Three
researchers conducted a study of neural tube defects (anencephaly,
encephalocele, spina bifida) in the offspring of Vietnam
veterans. They found that paternal blood levels of TCDD were
significantly associated with neural tube defects in their
children and that a particular paternal genotype (genetic
predisposition) could enhance this association.
LITANY OF BIRTH DEFECTS
Since 1990, Birth Defect Research for Children has collected
data on birth defects and developmental disabilities in
the children of Vietnam veterans. The National Birth Defect
Registry is a collaboration among seven prominent scientists
to identify patterns of birth defects and disabilities
in children with similar prenatal exposures.
When compared to non-veterans’ children in the registry,
the children of Vietnam veterans have shown consistent increases
in learning, attention, and behavioral disorders; all types
of skin disorders; problems with tooth development; allergic
conditions and asthma; immune system disorders including
chronic infections; some childhood cancers; and endocrine
problems including thyroid disorders and childhood diabetes.
More and more studies of prenatal exposures to dioxins and
similar chemicals are adding support for these associations.
According to Linda Birnbaum of the U.S. Environmental Protection
Agency, dioxin can modulate growth and development. In the
embryo and fetus, dioxin-altered programming can result in
malformations, anomalies, fetal toxicity, and functional
and structural deficits that often are not detectable until
later in life.
In a paper published in Environmental Health Perspectives,
Birnbaum discusses research that demonstrates that prenatal
exposures to endocrine disruptors (chemicals that can disrupt
hormone activity) such as TCDD can alter hormones, reproductive
tissue development, and increase susceptibility to potential
carcinogen exposure in the adult.
Increased susceptibility to chronic childhood infections
and cancers later in life may be a result of dioxin’s
effects on the developing immune system. Researchers in 2000
investigated the immunological effects of everyday exposures
to PCBs and dioxins in preschool-age Dutch children. The
researchers found that prenatal exposure to these chemicals
was associated with changes in the T-cell population. They
concluded that the effects of prenatal background exposure
to PCBs and dioxins persist into childhood and could be associated
with a greater susceptibility to infectious disease.
Another 2003 study by a team of researchers from Quebec
reported their finding of a chemical imbalance that could
be a marker for prenatal immune damage caused by organochlorines
(which include dioxin-like compounds). The researchers found
that the lymphocyte cells of newborns exposed to higher concentrations
of these chemicals during prenatal development secreted fewer
cytokines than those of a control group of newborns. These
alterations of the immune system could lead to increased
susceptibility to infection.
A growing body of evidence is linking prenatal exposures
to dioxin-like chemicals to learning and behavioral deficits.
At a Children’s Health Meeting
in 2000 sponsored by the National Institute of Environmental
Health Sciences, Jerry Heindel reported on several studies
of pregnant women who had consumed several meals of PCB-contaminated
fish per month during pregnancy and who gave birth to infants
with small but detectable learning and behavioral deficits.
The children with the highest exposure averaged six points
lower in IQ compared to children with lower levels of exposure.
A 2007 study from the Department of Preventive Medicine
at Kyungpook University in South Korea reported associations
between blood concentration of persistent organic pollutants
(including dioxins) and increases in learning and attention
disorders in children in the general population.
Thomas Zoeller, an endocrinologist at the University of
Massachusetts, has found that dioxin-like PCBs activate cellular
machinery that can alter the structure of other, non-dioxin-like
PCBs. Some of these dioxin-induced metabolites can act directly
on the thyroid hormone receptor. In the fetal brain, this
could alter the course of development leading to learning
and developmental disabilities.
The new research on dioxin and dioxin-like chemicals holds
the promise of unraveling the intricate ways in which these
chemicals can alter embryonic development. The research should
continue, but it is now 35 years since Agent Orange was first
sprayed in Vietnam. And the calls keep coming.
In Dioxins and Health, Thomas Webster and Barry Commoner
comment: “Much of the media coverage of the dioxin
debate has consisted of trying to convince the public that
their common sense is wrong and that experts know best. In
this case, the public’s view has been largely correct.
Dioxin is a dangerous and unwanted chemical pollutant.”
Vietnam veterans who would like to add information about
their children’s birth defects or disabilities to the
National Birth Defect Registry sponsored by Birth Defect
Research for Children can register online at www.birthdefects.org
Betty
Mekdeci is the executive director of Birth Defect Research
for Children.
|
fWar.jpg){kind=small}
