FEAT DAILY NEWSLETTER
Sacramento, California http://www.feat.org
December 19, 2001
News Morgue Search www.feat.org/search/news.asp
·
Study Offers New Insight Into Why Learning Disorders
Are Genetic
·
Air Pollution Harmful to Babies, Fetuses, Studies Say
[By Bijal P. Trivedi in National Geographic Today,
November 8, 2001.]
http://news.nationalgeographic.com/news/2001/11/1108_TVbrainmatter.html
Scientists analyzing new images of the brain have
discovered that structures associated with language are heavily influenced by
genetics. The finding begins to explain why learning disorders such as dyslexia
and autism can run in families.
The same study also revealed that the volume of gray
matter is strongly linked with IQ.
“Our study reveals there is a heritable component to
intelligence,” said neuroscientist Paul Thompson of the School of Medicine at
the University of California at Los Angeles, who led the research.
“The finding is particularly surprising,” he said, “because
you wouldn’t think something as general as the volume of gray matter could effect
something as complex as intelligence.”
The brain consists of two layers: gray matter and white
matter. Gray matter is a one-quarter-inch layer of brain cells surrounding a
ball of white matter. The white matter occupies the inner core of the brain and
contains the wiring that connects the brain cells. The gray matter is thought
to be the most important part of the brain for cognition and emotion.
Thompson and colleagues in Finland set out to determine
which brain structures are controlled predominantly by genes. They used
magnetic resonance imaging (MRI), which can distinguish between white and gray matter,
to produce brain images of identical and fraternal twins.
A comparison of the MRI scans revealed that the volume of
gray matter in the frontal lobe, the area just behind the eyes, is highly
heritable.
“But the volume of gray matter alone cannot be used to
gauge an individual’s IQ,” Thompson cautioned. The study found that differences
in the volume of gray matter account for only 10 to 15 percent of the variation
in intelligence.
“That’s good news,” said Thompson. “This shows how
important the ‘nurture’ part is.”
Science has long been divided about whether levels of
intelligence are shaped mainly by “nature” (genetics) or by “nurture,” which
refers to non-genetic factors such as education, environment, diet, rest, and
overall health.
The brain is a highly modular structure, with different
sections handling discrete tasks—reading, speaking, risk assessment, and visual
processing, for example. Thompson and his colleagues sought to find out whether
the size of these modules was influenced by genetics.
The MRI scans indicated that two areas of gray matter that
control reading comprehension and speaking (known respectively as Wernicke’s
area and Broca’s area) were highly similar in size in identical twins, which share
an identical set of genes.
The Broca’s and Wernicke’s areas were also similar in
non-identical twins, who on average share about half of their genes. But these
differences were greater than in the comparison of identical twins, and fewer
than in two unrelated individuals.
The study shows that the more closely related two people
are, the more likely they are to share similar brain structure in regions
heavily controlled by genetics. They are also more likely to share
vulnerabilities to specific diseases affecting these areas.
While these ideas are not new, Thompson’s work is the
first detailed study showing how strongly brain structure is determined by
genes and inheritance.
The results are described in the November issue of the
journal Nature Neuroscience.
Thompson’s study is part of a much broader effort to
understand which regions of the brain are associated with brain diseases such
as Alzheimer’s, schizophrenia, and Parkinson’s.
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Health: Smog is linked to stillbirths, infant deaths and
low birth weight.
[Take some toxic air, add dozens of vaccines, toss in
a little
mercury, pseudo-estrogens, and a nasty virus or two and we
have quite an
environmental assault stew mixed up for those vulnerable
ones of ours with
too many nerdy genes to take it - and there’s your autism in
there
somewhere, maybe. By
Gary Polakovic, LA Times. –LS.]
http://www.latimes.com/news/printedition/la-000099858dec16.story
A growing body of research from around the world indicates
that smog is exacting a much greater toll than previously known on infants and
unborn babies.
Scientists have long known that the extreme levels of air
pollution found in the developing world can harm babies, and that lesser
pollution in U.S. cities can sicken or kill the elderly and infirm.
The new research shows that the harmful effects of dirty
air can extend even into the womb. More than a dozen studies in the United
States, Brazil, Europe, Mexico, South Korea and Taiwan have linked smog to low
birth weight, premature births, stillbirths and infant deaths.
In this country, the research has documented ill effects
on infants even in cities with modern pollution controls, including Los
Angeles.
The findings have helped prompt California officials to
seek more stringent smog controls.
“Smog can harm the health of babies,” said Beate Ritz, an epidemiologist
at UCLA’s Center for Occupational and Environmental Health. “This should make us pause. Air pollution
doesn’t just impact asthmatics and old people at the end of life, but it can
affect people at the beginning of their life, and that can disadvantage people
throughout their life.”
A UCLA study conducted by Ritz and scheduled for release
Dec. 28, for the first time links air pollution and birth defects in Southern
California.
Other experts say that although worldwide research shows a
strong correlation between air quality and infant illnesses, it does not
establish a conclusive cause-and-effect connection.
Most of the studies have been analyzed by disinterested
scientists—a process called peer review—and have been published in leading
journals or will be soon. The studies differ on which pollutants are of most
concern.
Some implicate gases, others blame particles, and some
point to both.
“The research is suggestive, but preliminary. It’s
something to be
concerned about, but nothing to panic about,” said Tracey
Woodruff, a senior scientist for the U.S. Environmental Protection Agency and
an author of one of the research papers.
“It’s something we need to pay attention to.”
Frederick W. Lipfert, a New York environmental consultant
hired by auto makers, the steel industry, the U.S. Department of Energy and the
Electric Power Research Institute to critique several of the reports,
downplayed the findings.
“These studies raise more suspicions than smoking
guns,” he said.
Nonetheless, the research, especially the studies
focusing on U.S.
cities where pollution levels have been declining, is
regarded by health experts as troubling.
“We know there are serious health effects from low levels
of air pollution,” said Aaron Cohen, an epidemiologist and principal scientist
for the Health Effects Institute in Boston, a joint enterprise of the EPA and several
pollution-generating industries, including oil companies and utilities.
“When something affects babies and children, everybody
takes it seriously. I think it’s a high priority that we follow up on these
studies,” Cohen said.
In the latest research from UCLA, Ritz and a team of
researchers found that women exposed to high levels of ozone and carbon
monoxide were three times more likely than others to have babies with cleft
lips and palates and defective heart valves.
The researchers looked at thousands of pregnant women in
the Los Angeles area from 1987 to 1993, and compared those living in areas with
relatively dirty air to those living in cleaner areas.
Virtually the entire study area, bounded roughly by San
Bernardino, Santa Ana and Santa Clarita, met federal standards for carbon
monoxide, and much of the region complied with ozone requirements.
The study, to be published in the American Journal of
Epidemiology, found that the greatest risk occurs during the second month of
pregnancy, when a fetus gains most of its organs and much of its facial
structure.
The Clean Air Act regulates smog levels to protect certain
sensitive groups, including children, the elderly and people with respiratory ailments,
but not babies or fetuses.
Pollutants inhaled by pregnant mothers can reach fetuses
through the umbilical cord, research has found.
Most of the studies about smog and babies came after the
Clinton administration set new federal limits for ozone and microscopic
particles.
EPA officials say that before those standards can be
strengthened, more research is needed to determine which pollutants are most
harmful and at what stage of pregnancy they do the most damage.
However, California officials say they have seen enough.
Melanie Marty, chief of the air toxicology and epidemiology unit at the state
Office of Environmental Health Hazard Assessment, said the studies linking smog
and harm to babies are part of a body of evidence the state is relying on to recommend
that the Air Resources Board lower the statewide standard for airborne particle
pollution by 33%.
“These studies are very suggestive of effects in infants,
and in terms of public health, you want to protect against that rather than
wait for the most perfect study in the world,” Marty said.
Recently, more and more scientists—many of them women—have
been investigating whether ill effects of smog persist even where the pollution
has been reduced, as in much of the United States.
A study by scientists from the Harvard School of Public
Health and the University of Basel in Switzerland concluded that as many as 11%
of infant deaths in the United States—about 3,000 per year—may be a result of microscopic
particles in the air.
The study, which has yet to be published, expands on
earlier research by the EPA and Centers for Disease Control that looked at 4
million infants in 86 metropolitan areas and compared the incidence of
mortality with fluctuating rates of particulate pollution.
That study concluded that as particulate matter increased
in the air, the infant mortality rate rose by 10% to 40%.
In a separate study, a team of researchers from the United
States and Sweden found that pregnant women in five U.S. cities who were
exposed to elevated levels of carbon monoxide during their third trimester were
31% more likely to give birth to underweight babies.
They found that when concentrations of carbon monoxide
increased by 1 part per million, the risk climbed by nearly one-third.
The researchers, from Johns Hopkins University, the
Centers for Disease Control and Prevention and the Nordic School of Public
Health in Sweden, examined 90,000 births and air pollution trends between 1994
and 1996 in Boston; Hartford, Conn.; Philadelphia; Pittsburgh; Springfield,
Mass.; and Washington, D.C.
The findings were published in June in the journal
Environmental Health Perspectives.
Another study by UCLA researchers, which was published
last year and focused on Southern California, concluded that mothers are 20%
more likely to have a baby prematurely when exposed to elevated amounts of
microscopic particles in the final six weeks of pregnancy.
The analysis, which examined 97,518 newborns between 1989
and 1993, found the highest rate of premature births in eight communities where
smog levels were among the highest in the nation though generally in compliance
with federal standards.
The communities are Anaheim, Burbank, central Los Angeles,
El Toro, Glendora, Hawthorne, Long Beach and Santa Clarita.
The researchers adjusted the findings to account for a
variety of factors often related to premature birth, including the mother’s
age, access to prenatal care, smoking and illnesses such as lung disease,
diabetes and hypertension. They excluded births by caesarean section.
In a 1998 study of pregnant women in Sao Paulo, Brazil,
scientists found that women exposed to high levels of nitrogen and sulfur
oxides were 18% more likely to have their pregnancies terminate in stillbirths.
Nitrogen and sulfur oxides, produced by fuel combustion in
vehicles and factories, is more abundant in Sao Paulo than in U.S. cities.
The Sao Paulo researchers also found evidence of carbon
monoxide in the umbilical cords of 47 nonsmoking mothers.
The levels of carbon monoxide rose and fell with daily air
pollution levels. Carbon monoxide can cut off oxygen to a fetus, leading to
death.
The discovery of carbon monoxide in umbilical cords helps
explain how air pollutants reach a fetus and cause damage.
“There really is evidence that levels of air pollution
encountered in large cities worldwide may be hazardous to the fetus,” said Dana
Loomis, a co-author of the study and an epidemiologist at the University of
North Carolina.
“This is something that has not been recognized before. It
was always assumed the fetus was isolated in the womb from things in the
environment.”
The EPA is weighing the emerging body of research as it
considers whether to tighten its standard for airborne particles.
“We do see the trend. There is a growing body of
literature finding an association of conventional air pollution and infant
mortality,” said John D. Bachmann, associate director of science policy in the
EPA’s air division.
“Our review is in mid-process, and we are looking at
all of this.”
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