FYI, from another listserv.....
....note the part about Toronto -- more reasons to avoid using fossil fuels for power generation.
Air Pollution May Damage Brain, Heart
April 16, 2003 04:02:35 PM PST, HealthScout News
By Leonard Lee
WEDNESDAY, April 16 (HealthScoutNews) -- Air pollution may cause brain
damage similar to Alzheimer's disease, as well as heart problems, two new
studies suggest. Dogs exposed to air pollution were found to develop
damaged brain cell genes in as little as four weeks, according to
research presented April 15 at the Experimental Biology 2003 conference in San Diego.
The animals were exposed to the highly polluted air in different parts
of Mexico City, and compared against a control group of dogs kept in
less-polluted rural parts of Mexico. Mexico City is considered one of
the worst cities in the world for air pollution.
More than 200 dogs were involved in the study, which lasted for more
than a year. The dogs in the highly polluted environment suffered lung and upper
respiratory damage, which let particles enter the central nervous
system, leading to gene and DNA damage in their brain cells. Even dogs
less than 1 year old were found to have brain lesions similar to those
of human Alzheimer's patients, the researchers say.
Lead researcher Dr. Lilian Calderon-Garciduenas, of the University of
North Carolina, says exposure to air pollution causes inflammation in
the respiratory tract, which lets tiny airborne particles and metals
enter the central nervous system and brain. This, in turn, causes
oxidative damage and DNA changes in brain cells.
Air pollution breaks down the vital blood-brain barrier that usually
keeps toxic substances away from the brain, she says. "This is extremely
important," says Calderon-Garciduenas, "because once you break down the
barriers,you have an entrance for pollutants directly to your brain."
The researchers also found signs of lung damage in children as young as
4 years old who were raised in Mexico City. "The same breakdown in the
respiratory system we're seeing in dogs is happening in children and
adults in Mexico City," Calderon-Garciduenas contends, "and it probably
also happens in cities like Los Angeles."
A separate study presented at the same symposium found a link between
air pollution and heart problems in humans. Exposure to air pollution
raised levels of certain peptides in the bloodstream that can constrict
blood vessels and decrease blood flow to the heart muscle, the researchers found.
The study was conducted at the Gage Institute of the University of
Toronto, where healthy volunteers were exposed to air pollution in a
laboratory setting. The volunteers were subjected to air pollution about
two to three times the level normally found in Toronto, which is
considered one of North America's less-polluted major cities.
The study focused on endothelin, a naturally occurring peptide that
plays an important role in blood vessel health. "If we expose healthy
humans to airborne particulates, we can document a doubling of
endothelin in the blood," says Renaud Vincent, one of the researchers
and head of Health Canada's Inhalation Toxicology and Aerobiology Section.
"We now have at least one mechanism that could plausibly explain how
someone with a heart condition exposed to a low level of air pollution
could die or come down with severe symptoms, such as congestive heart failure," Vincent says.
Recent epidemiological studies have found higher rates of death and
hospitalization in cities with high levels of air pollution. Vincent
says the culprit appears to be airborne particulates. When test subjects
breathed polluted air for as little as two hours, the level of
vasoconstrictive peptides in their blood rose sharply and stayed at
abnormally high levels for as long as 24 hours, even without further
exposure. The changes in peptide levels were proportionate to the
concentration of particles to which the subjects were exposed.
"The picture is starting to come together of why we see these spikes in
mortality associated with air pollution levels," says Fred Miller, a
researcher with CIIT Centers for Health Research, an independent,
non-profit research organization based in North Carolina's Research
Triangle Park. "The mortality may be coming about because you have this
exposure, and how well can your system handle this added stressor?" he says.
Elevated levels of endothelin can reduce blood flow by as much as 50
percent, particularly in people with atherosclerosis, high blood
pressure and diabetes, Vincent says. Further study needs to be done on
which specific particulates and their components produce the rise in
vasoconstrictive peptide levels, he says.
To learn more about the health risks posed by air pollution, visit:
the Centers for Disease Control and Prevention
or the World Resources Institute.
or the Trust for America's Health