by Bette Hileman*
Over the past few decades, various disturbing trends have led
researchers to believe that environmental exposures are
contributing to children's declining health status in the U.S.
Federal and private health programs are just beginning to
realize the extent of the problem and to seek solutions.
Scientists are concerned that environmental exposures cause a
wide range of health threats to kids, including birth defects,
cancer, and asthma. According to a recent study from the
National Institute of Environmental Health Sciences (NIEHS),
childhood cancer incidence has risen 1% a year since the early
1970s, the prevalence of asthma has gone up sharply, the
incidence of attention-deficit hyperactivity disorder (ADHD)
may be increasing, a growing percentage of boys are born with
defects in their reproductive tracts, and the prevalence of
autism is rising dramatically....
[In late February the National Institute of Environmental
Health Sciences sponsored a meeting to examine a number of
specific environmental health risks to children, address ways
to translate science into action to protect children, and to
identify research gaps.]
...Former U.S. Public Health Service director Philip R. Lee
gave the keynote speech at the meeting. He described the types
of exposures likely to affect the health of the fetus and
children and some things that can be done to mitigate these
exposures. Lee is professor emeritus of social medicine at the
University of California School of Medicine.
Children are especially vulnerable to environmental insults,
Lee said. "At birth, their nervous, respiratory, reproductive,
and immune systems are not yet fully developed. They are in a
dynamic state of growth with cells multiplying and organ
systems developing at a rapid rate," he explained. Also, pound
for pound, children take in more air, food, and liquids than do
The impact of neurodevelopmental disorders such as ADHD on
children and their families is immense, Lee said. Children with
ADHD are at greater risk for dropping out of school early, drug
abuse, and suicide. Environmental exposure to any of a number
of known and suspected developmental neurotoxicants could
contribute to ADHD, including lead, mercury, manganese, tobacco
smoke, dioxins, polychlorinated biphenyls (PCBs), certain
pesticides, and solvents, he said.
One of the exposures society could easily reduce, Lee said, is
to manganese. Its effects include inattention, impulsivity, and
hyperaggression. Manganese -- an essential nutrient -- occurs
at very low levels in breast milk, but it is added to infant
formula made from cow's milk and occurs naturally at even
higher levels in soy formula. It is dangerous for infants to
consume more manganese than they would get from breast milk
because infants have no capacity to excrete excess amounts
until they are older, he said....
David O. Carpenter, director of the Institute for Health & the
Environment at the State University of New York, Albany,
discussed the effects of exposures to lead, mercury, and PCBs.
Children with higher lead exposures are more easily distracted,
less organized, and apt to be hyperactive, impulsive,
aggressive, and easily frustrated, he said. "Blood lead levels
as low as one microgram per deciliter are associated with
harmful effects on children's learning and behavior. There may
be no lower threshold for some of the diverse effects of lead
in children," he observed.
Low-dose prenatal exposure to mercury, Carpenter said, also
affects a broad range of skills -- motor, attention, and
language for instance. It decreases IQ and increases
impulsivity. "Children of women who consume large amounts of
fish and seafood during pregnancy" are at highest risk of
problems from mercury, he said. Immigrants, Native Americans,
and others who obtain much of their protein from subsistence
fishing are likely to be overexposed to mercury. Blood levels
of mercury in one-tenth of U.S. women of childbearing age
exceed the reference dose, the safe level, he noted.
Early life exposure to PCBs has similar effects, Carpenter
said. Infants with the highest exposure, as shown in cord blood
and breast milk, have abnormal reflexes and less developed
attentiveness to visual and auditory stimuli. Even 3.5 years
after birth, they have multiple behavioral problems, as well as
impaired thyroid and immune systems. What is totally unknown,
he explained, are the adverse effects if a child is exposed to
two or three of these substances--lead, mercury, and PCBs.
Exposure to air pollution such as ozone or nitrogen oxides is
associated with a wide array of health problems, said Jonathan
Samet, epidemiologist at Johns Hopkins University Bloomberg
School of Public Health. Prenatal exposures can cause pregnancy
loss and reduced birth weight. Postnatal exposures are
associated with cancer, sudden infant death syndrome, and
respiratory symptoms, he explained.
It is important, Samet continued, to look at the air quality of
the microenvironments where children spend a lot of time. For
example, most children spend time at home, at school, on
playgrounds, in school buses (an average of 40 minutes per day)
and parents' vehicles, and outside in neighborhoods, he said.
Inside the home, key exposures include tobacco smoke, nitrogen
oxides, wood smoke, radon, biological agents, volatile organic
compounds, and particles from outdoors, he said. Outdoor
exposures are to particles (especially from diesel smoke),
ozone, biological agents, and hazardous air pollutants.
"We know that high levels of combustion-related pollution
increase mortality and morbidity, including acute respiratory
illness," Samet said. "But increases in the incidence of asthma
cannot be explained solely by outdoor air pollution," he
"More research is needed, but we do know something," Samet
concluded. One is that children who live within 90 meters of a
main road have an increased risk of wheezing illness. Another
is that children who play team sports outside in areas with
high levels of ozone are much more likely to develop asthma
than those who play in clean areas. This is from a cohort study
of 3,522 children in Southern California with no history of
asthma. Also, among asthmatic children, the number of acute
events requiring emergency care goes down dramatically when air
quality improves. Emergency care and hospitalizations for
asthma declined 42% during the 1996 summer Olympic Games in
Atlanta when driving was sharply curtailed.
Peyton A. Eggleston, professor of pediatrics at Johns Hopkins
Bloomberg School of Public Health, noted that acute asthma was
more than twice as prevalent among black children (7.2%) as
among white children (3.0%) and that the annual death rate from
asthma among black children is more than twice as high (38.5
per million) as it is for white children (15.1 per million).
A study of hospitalizations for acute asthma in Baltimore from
1989 to 1999 shows that the number is lowest in summer and
peaks during September and October. Ozone levels outdoors are
highest in July and August, so this means "we need to look at
air quality indoors," as a causal factor, Eggleston said. Also,
he noted, "I think viral infections are important in causing
asthma problems in the fall."
In a National Cooperative Inner City Asthma Study, researchers
went to the homes of 1,528 asthmatic children in eight urban
centers, Eggleston said. They found that smoking occurs in 69%
of these inner-city homes, elevated nitrogen dioxide in 24%,
leaky roofs with water damage--which means mold is probably
present--in 29%, and excess roach allergen in the dust in 77%.
Children who were sensitized to mold, cockroaches, and dust
mites had many more emergency visits to the hospital. As a
group, the 1,528 children averaged 3.3 wheezing days every two
weeks and one emergency room visit every six months.
The 1% annual increase in the incidence of childhood cancer
since 1974 is primarily due to increases in leukemia and
central nervous system tumors, said Leslie L. Robison of the
department of pediatrics at the University of Minnesota. With
leukemia, however, "it is less clear whether we are looking at
an artifact or a true increase over time," he said. For central
nervous system tumors, better diagnostic techniques may explain
the increase, he said.
In any event, Robison said, one individual in every 600 is
diagnosed with cancer before the age of 15, about 8,500
children are diagnosed annually with cancer, and about 2,500
die each year. The highest incidence of cancer is in the first
year of life. "It is quite obvious these cancers are caused by
something that happened prior to birth," he explained.
A second peak of tumors occurs during the latter part of
adolescence. The most common cancers during this period are
Hodgkin's disease, bone and thyroid cancer, and melanoma....
There are known risk factors for some cancers, but they do not
explain the extent of the increase, Robison said. For example,
brain tumors and acute lymphoblastic leukemia can be caused by
ionizing radiation in utero. Acute myeloid leukemia can be
caused by ionizing radiation in utero or by chemotherapy, he
said. But there are no known risk factors for many childhood
cancers, such as neuroblastoma, retinoblastoma, Wilm's tumor,
hepatoblastoma, Ewing's sarcoma, and germ cell tumors.
Some of the environmental risk factors that may play a role in
childhood cancer include the pregnant mother's exposure to
tobacco, alcohol, cured meats, topoisomerase II inhibitors (a
class of cancer drugs), and improper doses of vitamins.
Postnatal exposures to pesticides and electromagnetic fields,
and parental occupations in agriculture, aircraft, pesticide,
painting, and pulp and paper industries may also contribute,
Robison said. It is likely that genes and environment are both
important in most childhood cancers, he said. "It is very
unlikely there are any cancers driven by genetics or
environment alone," he explained. But, he added,
gene-environment interactions have been investigated hardly at
At this point, "studies should focus on what actually we can do
to prevent childhood cancer," said Michael Thune of the
American Cancer Society. Much progress has been made in
treating cancer, but few advances have been made in identifying
cancer causes, he said.
Even though cancer clusters get a lot of media attention, few
scientific discoveries have been made from studying them, said
Tom Sinks of CDC's National Center for Environmental Health. A
confirmed cancer cluster can be the result of chance or a
miscalculation in the expected cancer rate.
However, a cluster of leukemia in Fallon, Nev., is interesting,
Sinks said. Fifteen cases of childhood acute lymphocytic
leukemia were diagnosed there when less than one would be
expected. "Fallon was warned for years about high levels of
arsenic in its drinking water," which remain very high, he
said. High tungsten levels have also been found in Fallon. When
compared with mean levels in CDC's latest national survey, 85%
of the people in Fallon have elevated tungsten levels, he said.
Godfrey Oakley, visiting professor of epidemiology at Rollins
School of Public Health at Emory University, pointed out there
is more about the environment than just contaminants that can
affect children's health, including vitamin deficiencies,
drugs, and maternal diseases. He said, for example, that folate
deficiency is known to cause birth defects, especially neural
tube defects. Folate deficiency is cheap and easy to solve by
fortifying flour and cereal with folate and taking vitamins. In
the U.S. since 1998, flour and some cereals have been fortified
with folate, but they are not fortified in Europe. "If you want
to make a significant reduction in birth defects, pay attention
to old problems," he said. Other known causes of birth defects
are the pregnant mother's use of valproic acid, Accutane, and
excess amounts of vitamin A; maternal diabetes; and rubella
during pregnancy, he said.
Terri Damstra of NIEHS discussed the World Health
Organization's global assessment of endocrine-disrupting
chemicals (EDCs)--substances that disrupt the endocrine
Exposure of the fetus or the young child to EDCs may result in
permanent changes in function, Damstra said, but exposure
during adulthood may not result in detectable effects. Another
feature of EDCs is that exposure to the same level during
different life stages may produce different effects.
One observed effect of EDCs is impaired neurobehavioral
development in children caused by fetal exposure to PCBs,
Damstra said. A weight-of-evidence approach looking at data
from all the relevant research indicates that EDCs in the
environment have potential for adverse outcomes on people.
"Coordinated international research strategies are urgently
needed to address numerous data gaps and uncertainties," she
said. "Prevention of exposure is the single most effective
means of protecting against environmental threats," she
Environmental agents can disrupt many cellular events in the
neurological development of the fetus, child, and early
adolescent, according to Ted Schettler, a physician who is
science director for the Science & Environmental Health
Network, a think tank that is concerned with the wise
application of science to the protection of the environment and
public health. These include cell division, migration,
differentiation, formation of synapses, pruning of synapses,
myelinization, and apoptosis.
For example, cell differentiation can be affected by exposure
to ethanol, nicotine, mercury, lead, and decreased thyroid
hormone, Schettler said. However, there are still many
uncertainties when trying to assess the effects of toxicants on
nervous system development. One is the "long latent periods
between relevant environmental exposures and emergence of
evidence of impairments. Therefore, waiting for proof of harm
before acting can result in widespread damage," he said.
"We are in the midst of a revolution in scientific
understanding of links between exposures and health that
promises to provide opportunities for new interventions to
protect public health," said John Peterson (Pete) Myers, senior
adviser to the United Nations Foundation. This revolution is
driven by research funded by many governments.
A result of these research efforts is a torrent of new papers
coming out virtually every week showing that many environmental
contaminants are biologically active. This research suggests
that adult chronic diseases will need fresh examination,
particularly with respect to the possibility that environmental
contaminants are programming the fetus so that chronic disease
develops later in life, he explained.
Despite these research needs, EPA's program on children's
environmental health may be scaled back. The agency's Office of
Children's Health Protection has been without a director since
April 2002, and the executive order creating the Presidential
Task Force on Children's Environmental Health & Safety will
expire on April 21. EPA has proposed to cut its annual funding
for the Centers for Children's Environmental Health from $6
million to $3 million. The centers are jointly funded by EPA
and NIEHS. If Congress approves this funding cut, the total
number of [children's environmental health] centers will
decline from 12 to 10.
* Bette Hileman is Senior Editor, Chemical & Engineering News,
a publication of the American Chemical Society. This is
excerpted from a longer article, "Children's Health," published
in Chemical & Engineering News April 7, 2003, pgs. 23-26. The
American Chemical Society is a professional association for
American Chemistry Council Will Spend $50 Million to Improve Its Image
From Plastics News March 31, 2003
HOUSTON (March 28, 2003) -- The American Chemistry Council
(ACC) may be taking a page from the American Plastics Council's
(APC) playbook in an attempt to improve its image. The ACC will
make a decision this spring on a communications program that
would be "similar in size and scope" [$50 million] to the one
APC launched several years ago, said Nova Chemicals Corp.
President and Chief Executive Officer Jeff Lipton, who serves
as an ACC board member.
"APC spends most of its money on TV commercials that focus on
young, married women," Lipton said.... " The commercials help
young, married women feel that they and their families are
safer because of plastic products.
"The concept has worked extremely well for plastics and it can
work the same way for chemicals."
[On April 4, 2003, Ad Age reported that the American Chemistry
Council had selected Ogilvy & Mather, New York, and its public
relations unit Ogilvy PR for its $50 million advertising campaign. The
American Chemistry Council is a trade association
for chemical corporations. --Peter Montague]