Evidence Of Chemical Effects On Children Mounts
From: Robina Suwol
Date: 22 Dec 2003
Remote Name: 188.8.131.52
Evidence of chemical effects on children mounts
By JOAN LOWY
Scripps Howard News Service 16-DEC-03
At Massachusetts General Hospital in Boston, Dr. Martha Herbert is seeing
younger and younger children who have been prescribed powerful drugs because
their behavior is "so extreme."
One 4-year-old was treated with Risperdol, an antipsychotic drug usually
prescribed to adult schizophrenics, because she tried to kill a sibling. "I've
had several cases like that," said Herbert, a pediatric neurologist. "It's
scary because this kind of thing hardly ever used to happen."
Across the nation, evidence of a growing number of children diagnosed with
attention, learning, behavioral and emotional disorders have perplexed doctors
and researchers and worried teachers and parents.
The disturbing conclusion some experts are reaching is that a significant
share of these conditions may be caused by environmental toxins that interfere
with brain development in children beginning in the womb and which may be
lowering the intelligence of the population at large.
There is no shortage of toxic suspects including lead, PCBs, mercury,
pesticides, dioxins, flame-retardants and alcohol. Most children are exposed
to some level of all these chemicals, raising the possibility of combined
effects - a question that scientists are only now beginning to research.
"You can almost think of the children who have been diagnosed with these
clinical syndromes as the tip of the iceberg," said Deborah Rice, a
toxicologist with the Maine Department of Environmental Protection.
"These are the kids that stand out, the ones that can actually go into a
doctor's office and the doctor can say, 'Yes, this child has autism,' " Rice
said. "But for every one of those children there may be many more children
that don't reach the clinical criteria, but nonetheless may have been affected
by the chemicals and other environmental milieu of a child's life."
Autism researcher George Lambert describes children as society's "canaries in
the coal mine" because they are so much more sensitive than adults to poisons
in the environment. They eat more food, breathe more air and drink more fluid
per pound of body weight than adults _ and their brains and nervous systems
are still developing. The most sensitive of all is the developing fetus.
In California, state health authorities have documented a 273 percent increase
between 1987 and 1998 in diagnosed cases of autism, a neurodevelopmental
disorder that usually appears before age 3 and can affect a child's ability to
communicate, form relationships and respond to the world around them.
Reported autism cases in California doubled again over the last four years and
the rate of increase appears to be accelerating, according to a follow-up
study released earlier this year. In November, the U.S. Department of Health
and Human Services held a two-day "autism summit" in Washington in response to
demands from parents of autistic children for greater federal action to
counter what they call a national "epidemic" of autism.
In North Port, Fla., kindergarten teacher Susan Owens said she has seen a
dramatic increase in attention and learning disorders in children of all
levels of intelligence and family income over the last 30 years.
Retarded students she taught in the late 1960s were better able to retain
basic knowledge and skills such as the days of the week or simple addition and
subtraction than many of today's kindergarteners of average intelligence, said
"I can go over the days of the week with my children now the entire year, but
if I say to them, 'Today is Friday. What will tomorrow be?' 50 percent of them
will still not be able to tell me that tomorrow is Saturday," Owens said.
Epidemiologists caution that personal observations or even documented trends
in diagnosis are not proof that any of these disorders is increasing in
children. Only a national study that investigates and tracks tens of thousands
of children - something that has never been done in the United States - would
be able to determine the true prevalence of these problems and whether they
are actually increasing.
"One can say there has been an increase in conduct disorders _ in violent and
aggressive behaviors _ over the last 50 years in children, but the problem
with saying the same thing about ADHD (attention deficit/hyperactivity
disorder) or autism is that we simply don't have good enough data to draw
conclusions," said Jane Costello, a psychiatric epidemiologist at Duke
University Medical Center.
What is clear is that scientific understanding of the potential effects that
toxins can have on the human brain has expanded markedly. Scientists now know
that the timing of the exposure is just as critical as the amount _ or dose _
of the toxin. Very small amounts of chemicals at critical windows in fetal
development or early childhood can have far more devastating effects than
greater exposure later in life.
Scientists also know more about the relationship between genes and environment
in the creation of disease. Even as researchers are linking individual genes
to specific diseases, they are also discovering that particular substances in
the environment can "turn off" or "turn on" these genes. The description often
used by scientists is that "genetics loads the gun, but environment pulls the
Studies of identical twins show that 68 percent of the time when one twin has
autism, the other twin will too, indicating that the disease probably has a
genetic link. But 32 percent of the time one twin will not have autism. Since
twins have identical genetic makeup, that means some environmental influence
is involved in autism as well, Lambert said.
Scientists also are exploring the relationship between ADHD and toxins known
to interfere with brain development. Rice found that monkeys exposed in early
life to lead and PCBs in amounts similar to what children often encounter
develop learning and behavioral problems that look remarkably like attention
PCBs (polychlorinated biphenyls) were widely used to insulate electrical
equipment until it was discovered that they were accumulating in the bodies of
people and animals virtually everywhere in the world. Although PCBs were
banned in 1972, children born three decades later still have small amounts of
the chemical in their bodies.
"This is not to suggest that ADHD is caused exclusively by neurotoxic agents
in the environment," Rice wrote in an article published in Environmental
Health Perspectives. "However, it seems reasonable to postulate that
environmental neurotoxicants contribute to the prevalence of ADHD currently
being identified in children."
An Environmental Protection Agency report earlier this year identified ADHD as
one of two "emerging issues" in children's environmental health. Children with
ADHD are characterized by having chronic inattention, impulsive hyperactivity
or both to an extent that daily functioning is impeded. The second emerging
issue identified by the EPA is mercury, a metal long known to be extremely
toxic to the human nervous system. The term "mad hatter" described the severe
effects of mercury used by 19th century hat makers in Danbury, Conn., to
Most Americans have small amounts of mercury in their bodies, primarily from
eating fish. Fish consumption in the United States has risen sharply since the
1980s, when doctors began urging patients to reduce beef in their diet to help
prevent heart disease.
Tests by the Centers for Disease Control and Prevention show 8 percent of
women of child bearing age have mercury levels in their blood that exceed the
government's safety standard. That means about 320,000 children are born each
year at risk for neurological damage from mercury.
Over the years, scientists have repeatedly lowered their estimates of how much
mercury people can tolerate. The same is true for lead, which has been known
for over a century to cause brain damage.
Two recent studies have concluded that there is no safe level for lead
exposure. Although lead levels in children have dropped dramatically,
government data show that about 90 percent of the nation's children have
between 1 and 10 micrograms of lead in their blood, which means they are at
risk for lowered intelligence.
While the dangers of lead, mercury and PCBs are established, scientists are
also discovering that chemicals with less well understood effects are
widespread in the environment and in people's bodies.
In 1999, researchers reported finding traces of a widely used group of
flame-retardants known as PBDEs in the breast milk of Swedish women. In
California, state toxicologists saw the Swedish study and decided to do their
own studies. Not only did they find PBDEs in every woman tested, but the
levels were significantly higher than those found in European women and they
were increasing rapidly over time.
Laboratory studies show some PBDEs can alter brain development in mice during
the important brain growth spurt. In humans, the growth spurt occurs from the
last trimester of pregnancy to age 2. The concern is that PBDEs could have the
same effect in children exposed through their mother's blood during pregnancy
and through breast milk after birth.
Alarmed, the California General Assembly passed a law earlier this year
phasing out the two PBDEs that showed the highest accumulation in women. Last
month, Great Lakes Chemical Corp. of West Lafayette, Ind., agreed to cease
production of the two chemicals by the end of 2004.
Industry officials contend children are not at risk from the flame-retardants
because levels found in women are too low to pose harm.
They also note that PBDEs are very effective flame-retardants, saving hundreds
of lives every year.
Some scientists see PBDEs as a cautionary tale.
"We came across PBDEs really by chance because we looked for it, found a
strange blip on screen and then it snowballed," said Tom McDonal, a
toxicologist with the California Department of Environmental Protection.
"There are thousands of chemicals used in commerce and hundreds of new
chemicals introduced each year, many of which we have very little information
on their human toxicity and even less information on exposures."
(Contact Joan Lowy at
Distributed by Scripps Howard News
Bill Walker, Vice President/West Coast
Environmental Working Group
1904 Franklin St. #703 Oakland CA 94612
t: (510) 444-0973 | f: (510) 444-0982
Last changed: March 14, 2006